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  • Use of novel film forming starch complexes to directly and indirectly reduce insect damage to plants
    Crop Prot. (IF 2.172) Pub Date : 2019-12-10
    William T. Hay; Robert W. Behle; Ursula M. Ruiz-Vera; George F. Fanta; Gordon W. Selling

    Film-forming polymer technologies can contribute to insect-pest control by causing adverse effects directly to insects such as slowing development, causing mortality, and/or indirectly as a spray ingredient that improves pesticide efficacy by resisting environmental degradation such as wash-off by rain. Amylose complexes produced from either fatty acid [amylose sodium palmitate (Na-Palm)] or fatty ammonium salts [amylose-hexadecylammonium chloride complex (Hex-Am)], when blended with polyvinyl alcohol (PVOH), dry to form films that were significantly more water resistant then films formed by their constitutive components and adhered strongly to treated soybean [Glycine max (L.) Merrill] leaves with no impact on photosynthesis or yield in simulated field trials. As an experimental bioinsecticide formulation to resist wash-off, AfMNPV baculovirus was incorporated into both amylose complex formulations and sprayed on soybean. After a simulated rain event, soybean treated with the baculovirus/Na-Palm/PVOH (1:1) retained 93% of the original insecticidal activity against Trichoplusia ni (Hübner) larvae as compared with the baculovirus only treatment, 53% activity retained. Curiously, initial insecticidal efficacy of film-forming treatments was significantly lower against T. ni when compared with unformulated baculovirus treatments, thus prompting further investigations. Both amylose complexes reduced larval feeding when sprayed on soybean, corresponding with reduced insect mortality by the baculovirus, which must be ingested to initiate infection. Hex-Am film coating over artificial diet inhibited the growth and development of T. ni and caused increased T. ni mortality and developmental delay as film thickness of Hex-Am/PVOH increased. These investigations demonstrate the potential of a new modified starch complex formulation to serve as a protective film forming agent and contribute to control of insect pests.

    更新日期:2020-01-04
  • Cacao agroforestry systems do not increase pest and disease incidence compared with monocultures under good cultural management practices
    Crop Prot. (IF 2.172) Pub Date : 2019-12-11
    Laura Armengot; Leone Ferrari; Joachim Milz; Fortunato Velásquez; Pierre Hohmann; Monika Schneider

    Pests and diseases threaten cacao production worldwide. Agroforestry systems are traditionally seen by farmers as one of the causes of increased pest and disease incidence, in contrast with full-sun monocultures. Cultural management practices—e.g. regular tree pruning, frequent pod harvest, regular removal of infested pods, weed management—have been reported to be crucial for pest and disease management. We performed two experiments for the purpose of assessing the effect of (i) different cacao production systems, and (ii) the frequency of harvest and removal of infested pods on the incidence of pests and diseases and on the cacao yield. The first experiment was performed in a long-term system comparison trial in Bolivia, where data on pest and disease incidence were recorded for three years in five production systems: two monocultures and two agroforestry system under organic and conventional farming, and one successional agroforestry system, i.e. a high tree density multi-strata system. Pest and disease management did not differ between systems and relied on cultural management practices. Overall, the incidence of pests and diseases did not differ between production systems, which indicated they were not the driver of yield differences between them. Across production systems, only 14% of the pods were affected by pests and diseases; 70% of these were affected by frosty pod rot. More than 80% of the pods infected by frosty pod rot were removed before the sporulation phase. In the second experiment, the effects of the frequency of harvest and removal of infected pods—every 15 days versus every 25 days—on pest and disease incidence and yield were tested in four farmers’ fields. Fortnightly harvest and diseased pod removal significantly decreased disease incidence and increased cacao yield, by 25% and 46% respectively. Our results show that cacao agroforestry systems do not increase pest and disease incidence compared with monocultures when good cultural management practices are implemented, which, in turn, can increase the productivity of the cacao plantations.

    更新日期:2020-01-04
  • 更新日期:2020-01-04
  • Effects of heat stress and exposure duration on survival characteristics of different developmental stages of Propylaea japonica, a dominant aphidophagous ladybeetle in China
    Crop Prot. (IF 2.172) Pub Date : 2019-12-16
    Netnapa Pumhan; Mi Tian; Li-Li Xu; Jun Jiang; Tong-Xian Liu; Shi-Ze Zhang

    Extreme high temperatures in summer become more and more universal. However, the effects of high temperature on fitness and performance of different developmental stages in most biological control agents are very limited. The purpose of this work was to evaluate the effects of heat stress and exposure duration on the survival characteristics of immature and adult stages of Propylaea japonica, a dominant aphidophagous ladybeetle in China. Here, we investigated the survival characteristics of different developmental stages in P. japonica when subjecting to high temperatures, 35, 37, 39, 41 and 43 °C for exposure durations of 1, 2, 4 and 6 h, respectively, and 25 °C is the control. The results indicated that egg survival greatly decreased only at 43 °C for 4 h or 6 h, and had no significant difference from 25 to 41 °C for any exposure duration. The younger larvae were the most vulnerable stage with the minimum survival exposure to high temperature but older larvae showed stronger resistance to heat stress. The survivals of pupae and adult stages rapidly decreased only at 43 °C for exceeding 2 h. These results suggest that different developmental stages of P. japonica possess different degrees of heat resistance, which ensures its survival in summer. Moreover, according to the heat resistance of several natural enemy insects in our previous reports and the present results, a comprehensive utilization strategy of aphid biological control was constructed to restrain aphid damage and population growth in challenging environment.

    更新日期:2020-01-04
  • Establishment of a qualitative PCR assay for the detection of Xanthomonas albilineans (Ashby) Dowson in sugarcane
    Crop Prot. (IF 2.172) Pub Date : 2019-12-16
    Heng-bo Wang; Nai-yan Xiao; Yong-jun Wang; Jin-long Guo; Ji-sen Zhang

    Xanthomonas albilineans (Ashby) Dowson (Xa) has devastating consequences on the vascular system of sugarcane plants and causes severe yield loss in sugarcane. In addition, the incubation period of the pathogen is long, and some infected varieties may remain symptomless for months and even years, leading to the spread of this pathogen over a large area. Therefore, it is important to establish a reliable and economical detection method for Xa. Based on the whole genome sequences of Xa, the hrpB gene was used to design 10 pairs of primers for the establishment of a novel qualitative PCR protocol. These pairs of primers were tested by species-specificity, annealing temperature, primer concentration and sensitivity. The most suitable hrp-10 primer pairs were chosen and used to detect the pathogen with assay sensitivity allowing the detection of 102 copies/μL of Xa purified DNA in suspension cultures. Moreover, sixty-eight sugarcane accessions (including 40 cultivars and 28 wild germplasms) with suspected infection by Xa from five provinces of China (Fujian, Yunnan, Hainan, Guangxi and Guangdong) were detected by the hrp-10 primer pairs. The results showed that the detection rate of the pathogen was 75% for symptomatic accessions, and 14% for asymptomatic samples. This newly developed PCR protocol provides a reliable and relatively inexpensive tool for the detection and identification of the pathogen Xa from infected sugarcane leaf.

    更新日期:2020-01-04
  • Application of waste material from celeriac as a control strategy for Burkholderia cepacia in soil
    Crop Prot. (IF 2.172) Pub Date : 2019-12-17
    Beata Kowalska; Magdalena Szczech; Urszula Smolińska; Robert Maciorowski

    Burkholderia cepacia is considered as one of the most harmful soilborne pathogens of onion. Currently used chemical or biological methods for the eradication of B. cepacia from soil are not effective. The aim of the study was to evaluate the possibility of eradication of the pathogen from soil using dried leaves of celeriac (Apium graveolens L. var. rapaceum Mill. cv. Albin). The leaves were crushed and added to the soil at a dose of 0.5, 1.0 and 2.0% (w/v) in the pot experiments and 0.25 and 0.5% (w/v) in container open-air experiments. The results showed that soil amendment with celeriac wastes significantly reduced B. cepacia abundance. The detrimental effect of celeriac leaves depended on the incubation time and dosage of the material. In the laboratory experiment B. cepacia was not isolated two months after the addition of 2% celeriac to infested soil. In the container experiment, in 2017, decrease of the pathogen population was observed two months after celeriac application, in June. The decreasing tendency of the pathogen population was maintained through all experiment duration. The addition of the dried celeriac leaves caused also the changes in population of soil microorganisms, especially increase of fluorescent Pseudomonas, spore forming bacteria and actinomycetes.

    更新日期:2020-01-04
  • Dichelops melacanthus and Euschistus heros injury on maize: Basis for re-evaluating stink bug thresholds for IPM decisions
    Crop Prot. (IF 2.172) Pub Date : 2019-12-17
    Emerson Crivelaro Gomes; Rafael Hayashida; Adeney de Freitas Bueno
    更新日期:2020-01-04
  • Forecast models of coffee leaf rust symptoms and signs based on identified microclimatic combinations in coffee-based agroforestry systems in Costa Rica
    Crop Prot. (IF 2.172) Pub Date : 2019-12-11
    Isabelle Merle; Philippe Tixier; Elías de Melo Virginio Filho; Christian Cilas; Jacques Avelino

    Coffee leaf rust is a polycyclic disease that causes severe epidemics impacting yield over several years. For this reason, since the 1960s, more than 20 models have been developed to predict different indicators of the disease's development and help manage it. In existing models, standardized periods of influence of the meteorological predictors of the disease are determined a priori, based on strong assumptions. However, the appearance of a symptom or sign can be influenced by complex combinations of meteorological variables acting at different times and for different durations. In our study, we monitored a total of 5400 coffee leaves during a year and a half, in different agroforestry systems, in order to detect the onset dates of the disease symptoms, such as lesion emergence, and signs, such as sporulation and infectious area increase. In these agroforestry systems, we also recorded microclimate. We statistically identified the complex combinations of microclimatic variables responsible for changes in lesion status to construct three models predicting lesion emergence probability, lesion sporulation probability and growth of its infectious area. Our method allowed the identification of different microclimatic variables that fit well with the knowledge about the coffee leaf rust biology. Minimum air temperature from 20 to 18 days before a lesion emergence explained the status change from healthy to emergence of visible lesion, possibly because the short germination phase is stimulated by low temperatures. We also found a unimodal effect of rainfall over a period of 10 days, 33 days before lesion emergence, with a maximum at 10 mm. Below this threshold, uredospore dispersal is efficient, increasing the lesion appearance probability; above this threshold, wash-off effects on uredospores probably occurs, decreasing the probability of lesion emergence. In addition, we identified microclimatic variables whose influence on coffee leaf rust had not been described before. These variables are likely to be involved in the internal development phases of the disease in the coffee leaves: (1) unimodal effects of maximum air temperature in different periods on sporulation and infectious area growth (2) positive and unimodal effects of rainfall in different periods on sporulation and (3) a negative effect of leaf thermal amplitude in different periods on lesion emergence, sporulation and infectious area growth. Although these models do not provide predictors of the level of disease attack, such as incidence, they provide valuable information for warning systems and for mechanistic model development. These models could also be used to forecast risks of infection, sporulation and infectious area growth and help optimize treatment recommendations.

    更新日期:2020-01-04
  • Medicinal plant volatiles applied against the root-knot nematode Meloidogyne incognita
    Crop Prot. (IF 2.172) Pub Date : 2019-12-20
    Marcela de Freitas Silva; Vicente Paulo Campos; Aline Ferreira Barros; Julio Carlos Pereira da Silva; Márcio Pozzobon Pedroso; Fabíola de Jesus Silva; Vanessa Alves Gomes; Júlio César Justino

    Despite several works revealing different plant species producing volatile organic compounds (VOCs) toxic to plant-parasitic nematodes, nematicidal activities of VOCs are poorly investigated in medicinal species. Therefore, this work focused on exploring the activities of VOC emitted from medicinal plant leaves against the root-knot nematode (RKN) Meloidogyne incognita. By in vitro assays, leaves of thirteen medicinal species emitted VOCs that significantly immobilize the second-stage juveniles (J2) of M. incognita, although only VOCs from Cymbopogon nardus and Dysphania ambrosioides killed more than 40% of J2. Thereafter, water exposed to VOCs from C. nardus or D. ambrosioides immobilized 46% and 79% of the J2, respectively. The galls and eggs of RKN were significantly reduced in tomato plants when the J2 were previously exposed to VOCs from C. nardus and D. ambrosioide at a concentration of 1.5% (w/w). Soil biofumigation using C. nardus and D. ambrosioides reduced the number of galls by 19% and 37%, respectively, by applying 2.4 g (2%) of macerates and reduced 80% the number of eggs by applying 9.6 (8.0%). The GC-MS identified compounds previously described as nematicidal compounds from both C. nardus and D. ambrosioides. The compounds ascaridole and citronellal, intensely emitted from D. ambrosioides and C. nardus, respectively, have already been described as toxic to RKN. However, isopulegol, dodecane and α-ionone from their volatilomes did not exhibit nematicidal effects. Nonetheless, D. ambrosioides and C. nardus produce VOCs toxic to RKN and should be exploited as biofumigant plants. Furthermore, nematicidal VOCs may represent new options for commercial products.

    更新日期:2020-01-04
  • Crop rotation effects on weed communities of soybean (Glycine max L. Merr.) agricultural fields of the Flat Inland Pampa
    Crop Prot. (IF 2.172) Pub Date : 2019-12-23
    Emilio H. Satorre; Elba B. de la Fuente; M. Teresa Mas; Susana A. Suárez; Betina C. Kruk; Antonio C. Guglielmini; Antoni M.C. Verdú

    Extensive grain crop production systems in the Flat inland Pampas mainly include soybean, double-crop wheat-soybean and maize in rotation. Due to difficult-to-control weed problems, farmers are tending to intensify the rotations in their fields by increasing the number of double crops or by including cover crops before the main crop. Land use intensification may be characterized using the intensification sequence index (ISI), which is the number of crops per year considering all crops sown in a particular period; i.e. the average number of crops sown in a time unit. To determine how agricultural intensification and crop sequences may modify weed communities, 31 soybean fields of commercial farms located in the Flat Pampa of Argentina were surveyed from 2012 to 2014. Frequency of individual weeds within the fields was determined and various statistical methods were used to evaluate changes in weed community composition or function due to intensification (ISI level). A total of fifty-three species, mostly therophytes (28 species), were recorded in soybean crop fields at harvest. Three weed communities were identified, which were related to the ISI level of the fields, and also to the number of years continuously sown with grain crops (i.e. number of years since the last pasture). Weed community under intensified fields was characterized by low species richness (p < 0.05); i.e. the number of weed species was reduced when more crops were sown per year. However, weed frequency (weed abundance) and weed functional groups were not significantly reduced by field intensification. Since weed problems in grain crops of the Pampas are increasing, mainly due to herbicide resistant weeds, the use of ISI as part of an integrated weed management strategy is discussed.

    更新日期:2020-01-04
  • Baseline sensitivity of Corynespora cassiicola to metconazole and efficacy of this fungicide
    Crop Prot. (IF 2.172) Pub Date : 2019-12-24
    Jiamei Zhu; Lingyan Zhang; Tongtong Li; Dicheng Ma; Yangyang Gao; Wei Mu; Feng Liu

    Triazole fungicides with broad spectra constitute the standard strategy for the management of fungal diseases of cucumber. In this study, the in vitro activities of metconazole were tested based on mycelial growth using 121 Corynespora cassiicola isolates. The distribution of EC50 values of metconazole for 121 isolates was a unimodal curve with a mean of 0.78 ± 0.41 μg mL−1. Cross-sensitivity data indicated that sensitivity to metconazole did not correlate with sensitivity to difenoconazole, tebuconazole, myclobutanil or hexaconazole (P > 0.05). The relative treatment effect values shown by in vivo assays with detached cucumber leaves and potted seedlings indicated that the protective and curative effects of metconazole were higher than those of difenoconazole. Field data suggested that the application of metconazole at 150 g a.i. ha−1 markedly reduced the disease severity and disease incidence of Corynespora leaf spot compared with the effects obtained with difenoconazole treatment, with relative treatment effects of 0.24 and 0.17 for 2017 and 2018, respectively. These findings demonstrate that metconazole could play a vital role in the integrated management of cucumber Corynespora leaf spot.

    更新日期:2020-01-04
  • Effects of complex cocoa-based agroforests on citrus tree decline
    Crop Prot. (IF 2.172) Pub Date : 2019-12-17
    E. Akoutou Mvondo; E.G.D. Ndo; M.L. Tsouga Manga; C.L. Aba'ane; J. Abondo Bitoumou; Bella Manga; L. Bidzanga Nomo; Z. Ambang; C. Cilas
    更新日期:2020-01-04
  • A review on the management of postharvest anthracnose in dragon fruits caused by Colletotrichum spp.
    Crop Prot. (IF 2.172) Pub Date : 2019-12-24
    Paa K. Bordoh; Asgar Ali; Matthew Dickinson; Yasmeen Siddiqui; Gianfranco Romanazzi

    Colletotrichum spp is one of the major cosmopolitan phytopathogens that cause postharvest anthracnose in dragon fruits. The pathogen attacks fruits on the field, during long-distance transport, and cold storage, leading to shorter shelf life. Traditionally, the plants are sprayed with synthetic fungicides, which is a strategic approach to control diseases in general and anthracnose in particular for dragon fruit production. Due to the demand for safe storage methods for consumers and the concerns about the use of synthetic fungicides, their use is restricted to control dragon fruits anthracnose after harvest. Despite “Umikai” (natural Calcium) is the commonly used preservative by some exporters of dragon fruits in Vietnam, recent reports indicated that Sodium nitroprusside (a Nitric oxide donor) markedly controlled anthracnose in dragon fruit at recommended levels. However, due to detrimental effect of these nitric oxide donors and other synthetic chemicals on human health, concerns are raised by the governments and other stakeholders to abolish, if not regulate the use of these synthetic chemicals in pre- and postharvest management of anthracnose. Consequently, several alternative methods have been developed to control postharvest decay, but with little success. This review summarizes the findings published within the last decade on current management practices on postharvest anthracnose in dragon fruit. We conclude that hot air/vapor heat treatment, water treatment, modified and controlled atmosphere packaging are commercially practiced and effective in reducing postharvest decay in dragon fruits while, X-ray irradiation is still under experimentation, Additionally, natural products (propolis and chitosan) shows promising effect without leaving residual harmful effect and could be adopted on a commercial scale to reduce postharvest losses after further commercial trials.

    更新日期:2020-01-04
  • Emamectin benzoate resistance risk assessment in Dysdercus koenigii: Cross-resistance and inheritance patterns
    Crop Prot. (IF 2.172) Pub Date : 2019-12-26
    Rabia Saeed; Naeem Abbas; Zahid Mehmood

    Dysdercus koenigii (Fabricius) is an economic pest in the cotton agro-ecosystem of Pakistan. Cross-resistance and inheritance patterns of emamectin benzoate resistance were explored in D. koenigii populations from Southern Punjab, Pakistan. After seven selection cycles with emamectin benzoate, a D. koenigii field population gained 48342-fold resistance to emamectin benzoate. The dominance value of emamectin benzoate resistance was 0.95 for both F1 and F1‡, suggesting complete dominant resistance. Backcrosses of hybrids with susceptible parents predicted polygenic resistance. Realized heritability of emamectin benzoate resistance was 0.59. When mean slope = 2.03 and h2 = 0.59, 4.8–1.6 generations were projected for a 10-fold increase in lethal concentration 50 (LC50) values at 45–95% mortality. Cross-resistance analyses revealed extremely high (411–69592-fold) cross-resistance to all tested insecticides when compared with the susceptible reference strain and extremely low cross-resistance to acetamiprid (resistance ratio (RR) = 2.6), low cross-resistance to imidacloprid (RR = 20). High cross-resistance to lambda-cyhalothrin (RR = 85) and extremely high cross-resistance to deltamethrin (RR = 2540) in emamectin benzoate-selected D. koenigii were also noted when compared to the field population. It can be concluded that the emamectin benzoate-selected strain revealed autosomal, completely dominant, polygenic resistance and high to extremely high cross-resistance to lambda-cyhalothrin and deltamethrin. These results will assist in improving management of D. koenigii.

    更新日期:2020-01-04
  • Influence of different environmental factors on the germination and seedling emergence of Ipomoea eriocarpa R. Br.
    Crop Prot. (IF 2.172) Pub Date : 2019-12-24
    Asif Tanveer; Mujahid Abbas Khan; Hafiz Haider Ali; Muhammad Mansoor Javaid; Ali Raza; Bhagirath Singh Chauhan

    Ipomoea eriocarpa R. Br., an annual prostrate plant, is a troublesome weed species in the tropical and sub-tropical regions of Asia, Africa, and Australia. For a better understanding of the plant's ecology, a seed germination study was conducted in order to predict the weed's ability to increase its global distribution, as well as presenting suitable management strategies for combating its spread. Germination and emergence of I. eriocarpa were examined in order to investigate the impact of abiotic factors such as temperature, salinity, moisture, soil pH, and burial depth on seeds. Germination and growth experiments were conducted under a completely randomized design with four replications. Maximum germination (77.5%) of I. eriocarpa occurred at 25 °C, decreasing according to an increase in temperature. A decrease in germination from 77.5 to 27.5% was observed where salinity increased from 0 to 200 mM of sodium chloride (NaCl). Germination of I. eriocarpa was 75% in no-water stress conditions; however, it gradually decreased with increasing water stress, with 32.5% germination at −0.8 MPa osmotic potential and no germination at −0.1 MPa osmotic potential. Germination was similar (74–76%) at pH levels ranging from 5 to 8 and decreased to 38% at pH 10. Optimal sowing depths ranged from 2 to 6 cm. Emergence decreased to 37.5% and 12.5% at burial depths of 8 and 10 cm, respectively. Our results suggest that I. eriocarpa has the potential to germinate, emerge and survive under different ecological conditions. Soil solarisation, organic manure application, and deep ploughing all respectively assist in altering the soil temperature, soil pH, and seed burial depths of I. eriocarpa, contributing towards the effective management of this weed species.

    更新日期:2020-01-04
  • Effect of spray volume, application timing and droplet size on spray distribution and control efficacy of different fungicides against circular leaf spot of persimmon caused by Plurivorosphaerella nawae
    Crop Prot. (IF 2.172) Pub Date : 2019-12-24
    Cruz Garcerá; Antonio Vicent; Patricia Chueca

    In recent years, Spain has been the scenario of the largest production growth of persimmon worldwide. However, circular leaf spot of persimmon, caused by Plurivorosphaerella nawae, was responsible for causing severe yield and economic losses. This work studied the effect of spray volume rate, droplet size, and application timing on spray distribution and disease control efficacy for mancozeb, pyraclostrobin and difenoconazole applications. Also fungicide degradation dynamics on persimmon leaves were studied. A method to inoculate persimmon plants using natural inoculum of P. nawae was developed. Results showed that spray volume influenced canopy spray coverage regardless of the fungicide used, but it did not influence disease control efficacy, except when pyraclostrobin was applied as pre-inoculation spray. Pyraclostrobin also showed a good post-inoculation activity. Influence of droplet size on spray coverage depended on the leaf side considered but it did not affect disease control efficacy except for pyraclostrobin applied 14 days after inoculation, when coarse droplets had lower control than fine ones. In general, slight degradation dynamics of fungicide residues on leaves were observed at 14 days.

    更新日期:2020-01-04
  • Resistance to insecticides in the field and baseline susceptibility to cyclaniliprole of whitefly Bemisia tabaci (Gennadius) in China
    Crop Prot. (IF 2.172) Pub Date : 2019-12-20
    Lei Guo; Haixiang Lv; Dan Tan; Ni Liang; Chenliang Guo; Dong Chu

    Resistance to multiple insecticides has become the biggest challenge to controlling Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae). In attempts to remedy the problem, four insecticides with novel modes of action (cyclaniliprole, cyantraniliprole, sulfoxaflor, and flupyradifurone) have recently been introduced to control B. tabaci. In the present study, we collected 18 B. tabaci populations in China from 2018 to 2019 to determine their resistance levels to six insecticides including the above four insecticides and two representative traditional insecticides (bifenthrin and imidacloprid). The results showed cyclaniliprole with LC50 values ranging from 3.4 to 21.2 mg/L was the most toxic insecticide to B. tabaci field populations and their average LC50 of 13.5 mg/L was used for the susceptible baseline to cyclaniliprole. The other three newly introduced insecticides (cyantraniliprole, sulfoxaflor, and flupyradifurone) also exhibited high toxicity to the field populations, however, the two traditional insecticides tested were of low toxicity with LC50 values ranging from 16.9 to 296.6 mg/L and from 33.1 to 397.0 mg/L for bifenthrin and imidacloprid, respectively. These results demonstrate that the newly introduced insecticides can currently be considered as effective alternative insecticides in insect resistance management programs for B. tabaci in China.

    更新日期:2020-01-04
  • Standard area diagram with color photographs to estimate the severity of coffee leaf rust in Coffea canephora
    Crop Prot. (IF 2.172) Pub Date : 2020-01-03
    Leônidas Leoni Belan; Leonardo Leoni Belan; Anatan da Matta Rafael; Carlos Alberto Gonçalves Gomes; Fábio Ramos Alves; Waldir Cintra de Jesus Junior; Willian Bucker Moraes
    更新日期:2020-01-04
  • Evaluation of tomato genotypes for resistance to bud necrosis disease caused by groundnut bud necrosis virus (GBNV)
    Crop Prot. (IF 2.172) Pub Date : 2020-01-03
    Amarjeet Kumar Rai; Y.B. Basavaraj; A.T. Sadashiva; M. Krishna Reddy; K.V. Ravishankar; Zakir Hussain; R. Venugopalan; K. Madhavi Reddy

    Bud necrosis disease has emerged as the major threat for tomato cultivation throughout the Asia, including India. Several strategies are being explored for the management of the disease and its vector thrips. Of the available, the most effective and practical way to manage the tospoviral diseases is to adopt resistant cultivars. However, work on development of resistant cultivars/hybrids to bud necrosis disease is very limited, due to the non-availability of resistant sources. Hence, in the present investigation, forty tomato genotypes comprising of nine different species were evaluated using two different GBNV isolates maintained at Indian Institute of Agricultural Research (IARI), New Delhi and at Indian Institute of Horticultural Research (IIHR), Bengaluru, under glasshouse conditions through mechanical sap transmission. Evaluated genotypes exhibited differential response in terms of symptom expression from mild chlorosis to severe bud necrosis, toppling and death of plants post GBNV infection. The genotypes which showed resistance and moderately resistance responses under glasshouse conditions were screened further under natural epiphytotic conditions along with two susceptible checks (PKM-1 and Pusa Ruby) at both the locations in all the three cropping seasons. Under field evaluation, only three genotypes (IIHR-2988, IIHR-2901 and IIHR-1940) were found to be resistant and three more (IIHR-2953, IIHR-2809 and IIHR-2101) were found to be moderately resistant, while the remaining thirty-four genotypes were turned out to be susceptible or highly susceptible. Maximum disease incidence (40%) under field conditions was recorded in the kharif crop. Significant difference was observed in the host response/severity to the two different isolates of GBNV, except in the resistant and moderately resistant lines. Furthermore, there was a high correlation between the findings of glasshouse and field-based screening, yet these results are to be validated further by thrips inoculation. Out of the nine different species of tomato evaluated, only S. chilense, S. peruvianum, and the advance breeding lines derived from them were showing resistance or moderately resistance response to GBNV. The resistant lines identified in the present investigation can be utilized to study the genetics of resistance and for the development of molecular markers linked to GBNV resistance, which subsequently will help to incorporate the resistant genes into several elite backgrounds of tomato.

    更新日期:2020-01-04
  • Tritrophic interactions in a wheat (Triticum aestivum), aphid (Rhopalosiphum padi) and parasitoid (Aphidius matricariae) system
    Crop Prot. (IF 2.172) Pub Date : 2020-01-01
    Khadijeh Jafari; Yaghoub Fathipour; Abdoolnabi Bagheri; Ali Asghar Talebi

    The effect of different wheat cultivars (Pishtaz, Pishgam, Parsi, Sivand, Sirvan, Tajan, Zarrin, Alvand, Shahriar and Darya) on the life table parameters of the aphid Rhopalosiphum padi (L.) and its parasitoid Aphidius matricariae Haliday was determined based on the age-stage, two-sex life table theory. All experiments were implemented in a growth chamber at 25 ± 1 °C, 60 ± 5% RH and a photoperiod of 16 L: 8 D hours. The results revealed that different wheat cultivars significantly affected development time and population parameters of the second (aphid) and third (parasitoid) trophic levels in a tritophic system. The shortest development time of R. padi was observed on both Pishgam (5.00 ± 0.13 d) and Alvand (5.03 ± 0.08 d). The longest development time was obtained on Shahriar (7.98 ± 0.21 d). The highest values of population growth parameters of R. padi were obtained on the Pishgam and Alvand cultivars, showing high susceptibility of these cultivars to the R. padi infestation. The tritrophic experiments conducted on the cultivars Shahriar and Pishgam revealed that A. matricariae parasitized more aphids on Pishgam and allocated higher intrinsic rate of increase on this cultivar compared with the resistant one. Regardless of the resistance pattern, the highest age-stage parasitism rate of A. matricariae on R. padi occurred on the first day of oviposition. However, the life history traits of R. padi and A. matricariae both decreased on the resistant cultivar, and, as this reduction was less in the parasitoid wasp, the combination of a resistant wheat cultivar and A. matricariae have potential for controlling R. padi in an IPM program, though additional field trials are needed to confirm this.

    更新日期:2020-01-04
  • Root-knot nematode population development in macadamia varieties
    Crop Prot. (IF 2.172) Pub Date : 2020-01-01
    Marylia Gabriella Silva Costa; Marcos José Perdoná; Maria José De Marchi Garcia; Silvia Renata Siciliano Wilcken

    Macadamia trees produce high quality nuts, and many Brazilian regions present ideal conditions for their cultivation. Aiming for financial returns during the first years of cultivation, macadamia have been grown as a coffee intercrop. Some Meloidogyne species are injurious to coffee trees, although information concerning the parasitism of these nematodes in macadamia nut trees is scarce. In this context, the aim of the present study was to evaluate the host status of seven varieties of macadamia nut tree (‘HAES-344’, ‘HAES-660’, ‘HAES 816’, ‘IAC 4–12B’, ‘IAC 9–20’, ‘IAC 4–20’ and ‘Aloha 10–14’) to Meloidogyne incognita race 2, Meloidogyne paranaensis and Meloidogyne exigua and to determine the life cycle dynamics of these nematodes in the ‘Aloha 10–14’ variety. For the resistance test, plants were infested with 5,000 eggs and J2 of each Meloidogyne species. Evaluations were carried out at 120 days after inoculation. The Gall index (GI), egg mass index (EMI) and reproduction factor (RF) were determined. To evaluate the life cycle of the Meloidogyne species in Aloha 10–14 roots, this variety was infested with approximately 300 juveniles of each species. Evaluations were carried out at 5, 15, 25 and 35 days post-inoculation. The progenies of all studied varieties were resistant to the assessed nematode species, and can be used as rootstock. The nematode life cycle was not completed in roots of the Aloha 10–14 variet, even at 35 days post-inoculation. Macadamia proved to be a good cultivation option for areas infested with root-knot nematodes.

    更新日期:2020-01-04
  • Contribution of shade trees to wind dynamics and pathogen dispersal on the edge of coffee agroforestry systems: A functional traits approach
    Crop Prot. (IF 2.172) Pub Date : 2019-12-26
    Stephanie Gagliardi; Jacques Avelino; Leïla Bagny Beilhe; Marney E. Isaac

    Through microclimate modifications, coffee agroforestry systems have both facilitative and inhibitory effects on the persistence of Hemileia vastatrix, a major fungal pathogen. Wind, a key element in the dispersal of H. vastatrix uredospores, is affected by shade tree presence, especially at the edge of agroforestry systems. However, little is known on how shade tree leaf functional and canopy-level architectural traits impact wind dynamics and subsequent airborne uredospore dispersal in this transition zone. In this study, we determine the contribution of shade tree leaf functional and canopy traits to changes in throughflow wind speeds and H. vastatrix uredospore dispersal at the edge of coffee agroforests across three size classes of the shade tree Erythrina poeppigiana (sparse (pruned shade trees), medium (conventional management) and dense (mature, larger, unpruned shade trees)). As expected, dense shade trees reduced throughflow speeds into the farm more frequently than the other size classes. Shade tree leaf functional traits (e.g. specific leaf area, leaf thickness, leaf angle) expressed high variability (coefficient of variations: 13.67%–89.48%) across the size classes and significantly predicted throughflow speed reductions (r2 = 0.891, P = 0.002). Emerging mature uredospore counts were significantly lower (P < 0.001) on the leeward side of dense shade trees, yet high reductions in throughflow speed into the farm were related to increased airborne uredospore capture across all size classes in these agroforestry systems. Seemingly, trade-offs exist between reduced wind speeds that decrease uredospore dispersal and reduced wind speeds that encourage uredospore settling into the coffee canopy at the edge of farms. This suggests a level of “fluidity” in desirable shade tree traits throughout the agroforestry system design. Our findings highlight the complexity of uredospore movement in agroforestry systems and the important role of shade tree canopy and leaf functional traits in wind dynamics.

    更新日期:2020-01-04
  • Management of common root rot and Fusarium foot rot of wheat using Brassica carinata break crop green manure
    Crop Prot. (IF 2.172) Pub Date : 2019-12-24
    Vito Campanella; Claudio Mandalà; Vincenzo Angileri; Claudia Miceli

    Brassica crop rotations have been associated with the reduction of pathogens, due to both the production of volatile sulfur compounds and changes in soil microbial community composition. In this research Brassica carinata, as break crop green manure, was evaluated for the control of common root rot and Fusarium foot rot of durum wheat in a complete randomized experimental scheme. Field trials were performed on seven farms, in some of the most representative areas of cereal production in Sicily, from 2011 to 2013. A total eradication of Bipolaris sorokiniana and Microdochium nivale populations following the B. carinata break crop, as compared to wheat monoculture, was found in all experimental fields. Fusarium culmorum population reduction ranged between 90% and 66%, with an average of 82% considering all field trials data. Symptoms or signs of common root rot were absent on wheat plants grown after the B. carinata break crop but were detectable on the wheat monoculture. Both incidence and severity of Fusarium foot rot were also reduced, by an average of 40.6% and 56.3%, respectively, following the B. carinata break crop in six of the seven field trials. After B. carinata break crop, wheat plant growth showed significant increases in height and weight, with an average increase of 48.3% and 49.0% respectively. Durum wheat grain yield was also significantly greater following the Brassica green manure, with increases ranging from 9.5% to 62.2%, as compared to wheat monoculture. B. carinata break crop green manure was also characterized by interesting results in terms of disease management in comparison to controls. These results suggest that the use of Brassicas such as B. carinata, as a break crop green manure, may potentially provide significant reduction of pathogens and disease development as well as improvement in grain yield of the succeeding crop.

    更新日期:2020-01-04
  • Managing the root rot disease of sunflower with endophytic fluorescent Pseudomonas associated with healthy plants
    Crop Prot. (IF 2.172) Pub Date : 2019-12-24
    Shumaila Moin; Syed Abid Ali; Khwaja Ali Hasan; Amna Tariq; Viqar Sultana; Jehan Ara; Syed Ehteshamul-Haque

    Use of pesticides is an effective way to control plant diseases but their excessive or misuse of chemical pesticides can cause environmental pollution. Whereas, biological control of plant diseases with saprophytic bacteria and fungi still giving inconsistent results, utilization of endophytic bacteria in plant disease management has been appeared as a new hope. In current study, 40 isolates of endophytic fluorescent Pseudomonas (EFP) were isolated from 20 healthy plants grown in experimental field of Karachi University and agricultural fields of Karachi and its suburb and identified according to Bergey's manual. Identification of ten potential isolates was also confirmed using genus-specific primer set i.e. PA-GS-R F 5′-CACTGGTGTT- CCTTCCTATA-3′ and PA-GS-F 5′-GACGGGTGAGTAAT GCCTA-3’. Phylogenetic reconstruction associated the fluorescent Pseudomonas as a descendent of P. monteilii and P. aeruginosa. Out of 40 isolates, 10 caused growth inhibition of all 4 test root rotting fungi Macrophomina phaseolina, Rhizoctonia solani, Fusarium solani and F. oxysporum in vitro. Most of them were found to produce hydrogen cyanide, volatile antifungal metabolites, ammonia and indole acetic acid besides solubilizing phosphate. In field plot experiments five selected isolates of EFP were applied as soil drench, significantly suppressed root rotting fungi of sunflower. EFP-121 was found highly effective in improving plant height and fresh shoot weight, than other isolates and carbendazim, a fungicide. Endophytic fluorescent Pseudomonas associated with healthy plants are seems to be an effective alternate to chemical fungicides.

    更新日期:2020-01-04
  • First report of southern blight of mung bean caused by Sclerotium rolfsii in China
    Crop Prot. (IF 2.172) Pub Date : 2019-12-18
    Suli Sun; Feifei Sun; Dong Deng; Xu Zhu; Canxing Duan; Zhendong Zhu

    Mung bean (Vigna radiata) is an important legume crop in China. An emerging mung bean disease with symptoms resembling southern blight was detected in China. This study was conducted to confirm and characterize the responsible pathogen through cultural and morphological characterization, and molecular detection using multiple specific primers and multiple-clone sequence analysis of the rDNA internal transcribed spacer (ITS) region and the translation elongation factor 1α (EF1α) and RNA polymerase II subunit 2 (RPB2) genes. All isolates obtained from mung bean were identified as Sclerotium rolfsii. Interestingly, we found that rDNA ITS, EF1α, and RPB2 sequences of all isolates consisted of two distinct types, which likely originated from different nuclei. Our findings indicated that S. rolfsii isolates were heterokaryotic and contain a heterozygous genome. Two trials of pathogenicity and host range revealed that all S. rolfsii isolates were not only strongly virulent to mung bean but also to several other important crops, indicating their potential threat to future agricultural production. To our knowledge, this is the first report of S. rolfsii causing southern blight on mung bean in China.

    更新日期:2020-01-04
  • Pest-regulating networks of the coffee berry borer (Hypothenemus hampei) in agroforestry systems
    Crop Prot. (IF 2.172) Pub Date : 2019-11-30
    Leïla Bagny Beilhe; Sacha Roudine; José Alcides Quintero Perez; Clémentine Allinne; Djavan Daout; Rémi Mauxion; Dominique Carval

    Pest regulation in agroforestry systems (AFS) is beginning to be well-recognized, but the mechanisms implied in the interaction network between the environment, pests and predators in AFS are still not well-described. The aim of this work is to understand how plant diversity associated with AFS regulates the coffee berry borer (CBB) taking into account a tripartite interaction network: pest–predator–environment. It further seeks to understand how farmers' management practices can modify the regulating network. Using field data from coffee-based AFS and structural equation modeling, we assessed the effects of environmental conditions (% shade cover, tree area surface, coffee density) and farm management (conventional, integrated, organic) on (1) ant predatory groups, (2) the abundance and the damage from CBB and (3) their interactions. Percentage of shade cover was positively correlated to CBB initial infestation (through direct effect) and negatively through its effect on coffee phenology. A higher percentage of shade is also negatively related to damage intensity. Farmers’ practices significantly reduced the CBB population without considerable side effects on the ant predatory group, probably due to the high plant diversity within these farms. The abundance of the most diversified ant predatory group has a top-down effect on the peak of the CBB infestation rate. Our approach appears promising for a better understanding of the complex regulating network in coffee AFS and confirms the importance of an integrated management strategy to reduce CBB damage.

    更新日期:2020-01-04
  • Characterization of cropping practices, pest constraints, and yield variation in irrigated lowland rice of Cambodia
    Crop Prot. (IF 2.172) Pub Date : 2019-08-06
    Nancy P. Castilla; Alexander M. Stuart; Ouk Makara; Khay Sathya; Soeur Somany; Virender Kumar; Buyung Asmara Ratna Hadi

    Characterization and analysis of the relationship between cropping practices, pest constraints, and yield variation in Cambodia are necessary for developing sustainable crop and pest management strategies as agriculture intensifies. Rice production is transforming from subsistence to a market-oriented, intensive system. Field surveys were conducted during the wet season (May to December) of 2016 in two districts of each of the four main rice-growing provinces. The intensity of injuries caused by pests (diseases, insect pests, rodents and weeds) and yield were assessed in farmers’ fields. Data on cropping practices were obtained through structured interviews of farmers who managed the surveyed fields. The average yield was 4.03 t ha−1, which was threefold higher than the yield obtained in 1990. Comparison of results with those obtained from surveys in the 1990s indicates a substantial increase in the proportion of direct-seeded fields, reliance of farmers on pesticides, and seeding and nutrient rates. PCA and correlation analyses showed that these cropping practices favored the occurrence of rodents, brown spot, and weeds, which were most closely associated with low yield. Correspondence analysis identified three groups of fields with varying levels of intensification, pest profiles, and yield levels. Cropping intensification was highest in areas where IR50401-77-2-1-3, a modern variety, was grown and lowest in areas where Phka Rumdoul, a traditional variety, was transplanted. Farmers managed pests by relying on pesticides and increasing the seeding rate. In general, increasing agricultural inputs did not affect the intensity of pest injuries, or increase yield, indicating that these can be reduced or optimized without compromising yield and pest management efficiency. To reduce reliance of farmers on pesticides as the main strategy for pest management and promote sustainable rice production, there is a need to create an enabling environment for the adoption of ecologically based pest management approaches and provide economic incentives, such as certification of rice grown under sustainable production standards and linking farmers with market networks for sustainably grown rice.

    更新日期:2020-01-04
  • Rice blast management in Cambodian rice fields using Trichoderma harzianum and a resistant variety
    Crop Prot. (IF 2.172) Pub Date : 2019-06-28
    Cheythyrith Chou; Nancy Castilla; Buyung Hadi; Toshiharu Tanaka; Sotaro Chiba; Ikuo Sato

    Rice blast (Pyricularia oryzae Cavara) is one of the most devastating diseases affecting the rice crop in Cambodia and other countries in the world. The fungus Trichoderma spp. is known as one of biological control agents applied as a soil treatment, seed treatment and foliar application, that is used for suppression of various diseases caused by fungal pathogens. Trichoderma harzianum strain BTB 022 is one of the commercial biological control products available in Cambodian markets. The combined use of T. harzianum and a resistant variety, to manage blast disease, are considered as sustainable approaches to reduce yield losses and to cope with recent restrictions on fungicide use. A series of consecutive experiments was conducted to examine the effectiveness of T. harzianum on suppression of rice blast incidence in Koktrap and Polors agricultural research stations during wet and dry seasons in 2016 and 2017. In both years, the treatments consisted of the use of Trichoderma on susceptible and resistant rice varieties. In 2017 the two treatments were combined with conventional practice treatments representing the average farmers' practice. The experiments were arranged in randomized complete block design with three replications in 2016 and four replications in 2017. Leaf blast incidence was assessed at five and four growth stages in 2016 and 2017, respectively, and the area under the leaf blast progress curve (AULBPC) was computed for each year and location. Neck blast (NB) incidence was assessed at dough stage and grain yield (GY) was measured at ripening stage. T. harzianum reduced the incidence of leaf blast and neck blast on IR504 (susceptible strain), but its efficacy was not consistent. The magnitude of disease suppression by T. harzianum was higher for neck blast than for leaf blast. GY variation was correlated with AULBPC and NB incidence, which suggests that disease reduction corresponded to an increase in yield (AULBPC: r = −0.877, P < 0.001; NB incidence: r = −0.567, P < 0.001). T. harzianum effectively reduced neck blast at high disease pressure. Growing a resistant variety, e.g. CAR14, effectively reduced AULBPC and NB incidence compared to T. harzianum and farmers’ practice of fungicidal use but the association of T. harzianum and resistant variety did not increase the effect in the control of disease.

    更新日期:2020-01-04
  • Effects of anaerobic soil disinfestation carbon sources on soilborne diseases and weeds of okra and eggplant in Nepal
    Crop Prot. (IF 2.172) Pub Date : 2019-06-12
    Ram B. Khadka; Madan Marasini; Ranjana Rawal; Anna L. Testen; Sally A. Miller

    Soilborne diseases, root-knot nematodes (Meloidogyne spp.), and weeds are the major yield-limiting factors in okra (Abelmoschus esculentus) and eggplant (Solanum melongena) production in Nepal. Anaerobic soil disinfestation (ASD) is a promising technique in developed countries to control soilborne pests, but it has not been tested in many developing countries. Experiments were conducted in the western plain region of Nepal in okra and eggplant from March to July 2016 and October 2016 to April 2017 (eggplant only) to compare locally available carbon sources for efficacy in ASD. Experiments were conducted in a randomized complete block design with three replicates of seven amendments (molasses 2 kg m−2, rice bran 2 kg m−2, rice bran 1 kg m−2 plus molasses 1 kg m−2, raw goat manure 2 kg m−2, mustard (Brassica campestris var. toria) cake 1.5 kg m−2, lentil (Lens esculenta) husks 2 kg m−2, and berseem clover (Trifolium alexandrinum) leaves 3 kg m−2), and a non-amended, uncovered (aerobic) control in the first year. Lentil husks and berseem clover were replaced by wheat bran (2 kg m−2) and wheat bran (1 kg m2) plus molasses (1 kg m−2) in the second year. Carbon sources were incorporated into soil followed by irrigation to saturation, and plots were covered with white plastic sheeting for 21 days. Significantly lower Fusarium wilt incidence, root-knot disease severity, and weed biomass were observed in ASD-treated eggplant plots compared to the control in 2016; disease, root-knot and weed pressure were low in 2017 and differences were not significant. Root knot disease severity and weed biomass were significantly reduced compared to the control in ASD-treated okra plots, depending on the carbon source used. With the exception of plots amended with molasses (eggplant, 2017) or molasses alone or combined with rice bran (okra), significantly higher fruit yields were observed in ASD-treated plots than in control plots. ASD appears to have great potential in Nepal because of its broad-spectrum impact on multiple soilborne pests and ready availability of inexpensive local inputs.

    更新日期:2020-01-04
  • Temporal and spatial patterns of research on a globally significant invasive weed Parthenium hysterophorus L.: A bibliographic review
    Crop Prot. (IF 2.172) Pub Date : 2019-06-04
    Seerjana Maharjan; Bharat B. Shrestha; Anjana Devkota; Rangaswamy Muniappan; Pramod K. Jha

    Parthenium hysterophorus L. is a globally significant environmental and agricultural weed that is rapidly spreading from its native range in the tropical Americas to tropical and subtropical regions of all continents. We analyzed temporal and spatial patterns of research done on this weed across the world. Research articles were accessed from online databases, Web of Science (WOS) and Chinese National Knowledge Infrastructure (CNKI) and previously published review articles. A total of 428 research articles in 161 SCIE/SSCI indexed journals was published from 1970 to December 2018 out of which 76% of the research was conducted in South Asia. Asian journals had more publications than European and American journals revealing concern for invasion, and more effort on the development of management strategies. Most of the research was conducted on potential uses (19%), allelopathic effect (17%) and phytochemical studies (13%) of this weed. Even though the plant has invaded 49 countries outside of its native range, research publications were available only from twelve (25%) countries. The extent of the geographic areas and ecosystems invaded by this weed is still not known for all the countries where it has been reported. We contend that the continuing spread of this weed is due to lack of timely and adequate knowledge and research in the introduced range. Our search of the literature indicates that to prevent the rapid spread of this weed and to economically manage this pest where it has already invaded, increased research activities and effective technologies for various control measures and competitive displacement by using different plants must be established in all the invaded countries.

    更新日期:2020-01-04
  • Survey, morphology and white mold disease of country bean (Lablab purpureus L.) caused by Sclerotinia sclerotiorum (Lib.) de Bary in-relation to soil physico-chemical properties and weather conditions in Bangladesh
    Crop Prot. (IF 2.172) Pub Date : 2019-05-25
    M.S. Nahar; Najmun Naher; M.J. Alam; M.J. Hussain; L. Yasmin; M.Y. Mian; S.A. Miller; C. Rosa

    A survey was conducted to document the incidence of white mold disease in country bean production areas at Bogra, Pabna, Jessore, Sylhet, Hobigonj and Gazipur districts in Bangladesh during 2016–17. A total of 115 farmers’ fields was surveyed from early vegetative to end of harvesting stages. Pathogens were collected from diseased stems, racemes and pods. Soil samples were collected from the same fields. White mold disease was identified based on symptoms in the field. White mold disease infection was recorded in 100% of the surveyed fields in Shahjahanpur upazila of Bogra district, while approx. 90, 80, 60 and 20% of the fields were infected in Bahubal of Hobigonj; Golapganj of Sylhet; Ishordi of Pabna and Monirampur of Jessore, respectively. White mold was not found in any of the fields surveyed in Joydebpur, Gazipur. Disease incidence and severity were higher in Shahjahanpur of Bogra and Bahubal of Hobigonj district. Moderate disease incidence and severity were observed in Golapganj of Sylhet. Pathogen infection was higher in the fields with loamy fine sandy soil with pH of 5.11–6.22. Globose to irregular black sclerotia developed in infected plant parts and the sclerotia germinated and produced apothecia in the fields after rain. Hyaline, branched, well developed and septate mycelia developed on potato dextrose agar medium. The hyphae were 2.0–7.2 μm in width. After five days of incubation, the subsurface mycelial cells swelled and formed dark black sclerotia. The sclerotia were 1.5–6 mm in width and 2–17 mm in length. Sclerotia germinated, and brown colored round to globose shaped apothecia developed at the end of a long stipe. The length and diameter of apothecia were approximately 4–21 mm and 2–8 mm, respectively. Asci were hyaline and cylindrical in shape, while the ascospores were elliptical. The size of ascus and ascospore was 68–155 × 4.5–6.01 μm and 4.7–6.94 x 4–6.2 μm, respectively. Calcium oxalate was formed on the wall surface of the asci. Disease incidence was negatively correlated with pH and calcium content in the soil while apothecia formation was positively correlated with rainfall and humidity.

    更新日期:2020-01-04
  • Integrated pest management for yard-long bean (Vigna unguiculata subsp. Sesquipedalis) in Cambodia
    Crop Prot. (IF 2.172) Pub Date : 2019-05-09
    Antonino Malacrinò; Kim Hian Seng; Chanratha An; Socheath Ong; Megan E. O'Rourke

    Pesticides are widely used to protect crops against insect pests and diseases. However, current conventional pest management strategies can severely impact environmental and human health. Therefore, it is timely to find an alternative to conventional chemical control in order to counteract the negative effects of pesticides. Integrated Pest Management (IPM) represents a promising alternative in vegetable production to reduce pesticide use while also maintaining acceptable yields. In this study, we compared an IPM strategy with conventional management and a no-spray control for managing arthropod pests and pathogens in yard-long bean (Vigna unguiculata subsp. Sesquipedalis), an important crop in Southeast Asia. We conducted the study during two crop cycles (rainy and dry season) on 24 farms (12 per season) spread across the Soutr Nikum district of Siem Reap, Cambodia. In both seasons, our IPM strategy controlled overall pest levels better than conventional pest management, which exhibited better pest control than the no-spray control. This pattern was not reflected by yields, however, since dry season yields were similar across all three treatments (conventional = 1.68, IPM = 1.73, control = 1.52 kg m−2), and rainy season yields were similar between conventional and IPM treatments, which were higher than yields in the no-spray control treatment (conventional = 1.74, IPM = 1.71, no-spray control = 1.33 kg m−2). The costs of IPM were higher than conventional management, which contributed to lower profits in the IPM treatments in both seasons despite yields being as high as in conventional production. Therefore, future efforts should focus on increasing the profitability of IPM production.

    更新日期:2020-01-04
  • Comparison of biorational management approaches against mango fruit fly (Bactrocera dorsalis Hendel) in Bangladesh
    Crop Prot. (IF 2.172) Pub Date : 2019-05-03
    M.S. Hossain; B.C. Sarkar; M.M. Hossain; M.Y. Mian; E.G. Rajotte; R. Muniappan; M.E. O'Rourke

    Mango (Mangifera indica L.) is a major fruit crop throughout the tropical and sub-tropical regions of the world including Bangladesh. The Oriental fruit fly, Bactrocera dorsalis (Hendel) (Diptera: Tephritidae) is a major pest of mango causing both quantitative and qualitative losses as well as export barriers. We compared the efficacy and economic benefits of several prophylactic and remedial tactics against B. dorsalis during the 2017 mango cropping season in pursuit of the development of a mango IPM program to produce fruit fly-free and residue-free mango fruits. Several non-chemical approaches, such as bagging fruits with double-layer brown paper bags, cloth bags, polythene bags, and installing methyl eugenol kairomone traps and protein hydrolysate bait lures, were evaluated and compared with conventional Profenofos + cypermethrin (Shobicron 425 EC) management. Among the treatments, bagging mangos with double-layer brown paper bags at forty-two days before harvest showed the best performance. Fruit infestation was reduced to zero, marketable yields were significantly higher than with conventional pesticide management, and the marginal benefit cost ratio of bagging mangos with double-layer brown paper bags was nearly twice as high as any other treatment. The strong economic return from bagging fruits with double-layer brown paper bags results from high fruit quality and being able to use the bags for two growing seasons. The positive results from this study indicate that double-layer brown paper bagging is effective at controlling the oriental fruit fly in mango and should be integrated into a full IPM package for mango production.

    更新日期:2020-01-04
  • How do stakeholder interactions in Cambodian rice farming villages contribute to a pesticide lock-in?
    Crop Prot. (IF 2.172) Pub Date : 2019-04-25
    Rica Joy Flor; Harro Maat; Buyung Asmara Ratna Hadi; Rathmuny Then; Emily Kraus; Kry Chhay

    This paper addresses the conditions and mechanisms that sustain pesticide use by Cambodian rice farmers and constrain a transition to more sustainable pest control practices. We analyzed data from a survey of individual farmers (N = 320), focus group discussions with farmer groups, and interviews with input sellers, rat hunters and local extension agents. Our findings show that farmers mix different types (e.g. herbicides and insecticides) and brands of pesticides in one application. Other chemicals, in particular ‘growth activators’ are often added to these mixes. The interaction patterns and financial arrangements among farmers, pesticide sellers, and laborers promote or sustain these practices. Increasing returns to information and recursive social interaction at the community level thus create a lock-in situation for pesticide use. These findings have direct implications on targeting interventions, which are often aimed at providing knowledge to government extension agents and farmers. Our results suggest that farmers’ knowledge on pest management is not the only driver for their decisions and practices. A broader scope of intervention in communication and feedback loops between stakeholders directly interacting with farmers can help to diversify the suite of recommendations while providing a balance in the information that reaches farmers. Changes in these social arrangements and informal rules may be required to affect positive changes in rice pest management.

    更新日期:2020-01-04
  • Beneficial bacterial volatile compounds for the control of root-knot nematode and bacterial leaf blight on rice
    Crop Prot. (IF 2.172) Pub Date : 2019-04-17
    Hung Xuan Bui; Buyung A.R. Hadi; Ricardo Oliva; Nathan E. Schroeder

    Microbial volatiles can promote plant growth and suppress diseases, nematodes and insects. Our knowledge of the effects of microbial volatiles on monocots such as rice and its pathogens and pests is still incomplete. As part of a screening initiative for beneficial bacterial species, we identified three strains (Bacillus sp., Paenibacillus sp. and Xanthomonas sp.) lethal to the rice root-knot nematode (Meloidogyne graminicola). Using both in vitro and in planta dual-chamber pot experiments, we found that volatiles from the beneficial bacteria were lethal to M. graminicola J2s and significantly reduced infection of susceptible rice. We conducted similar in vitro and in planta experiments against rice bacterial leaf blight Xanthomonas oryzae pv. oryzae. Exposure to bacterial volatiles inhibited the growth of X. oryzae pv. oryzae by 50–60% in vitro, but did not impact infection in planta. Finally, we found that bacterial volatiles from Bacillus sp. and Xanthomonas sp. inhibited rice germination and seedling development in vitro but did not affect plant growth in planta. These findings suggest that volatiles from beneficial bacteria have the potential to control M. graminicola, but that high volatile concentrations may inhibit plant growth.

    更新日期:2020-01-04
  • Weed management practices of smallholder rice farmers in Northwest Cambodia
    Crop Prot. (IF 2.172) Pub Date : 2019-04-16
    Sokunroth Chhun; Virender Kumar; Robert J. Martin; Pao Srean; Buyung A.R. Hadi

    One-hundred farmers from lowland rice systems of Battambang province in Cambodia were surveyed in 2017 using a structured questionnaire with the objectives to (1) determine farmers' current knowledge and weed management practices and document the effect of adopted agronomic practices on management of weeds in rice, and (2) quantify the extent of weed seed contamination in farmers’ own saved paddy seed lots. To estimate the level of contamination by weed seeds, a one kg paddy seed sample was collected from each surveyed farmer. All farmers practiced broadcast direct-seeded rice (DSR), with an average seeding rate of 181 kg ha−1. For sowing the rice crop, 82% of farmers used their own saved seeds or bought seed from their neighbour. All the paddy seed samples were contaminated with seeds of 34 weed species with an average of 1,070 weed seeds kg−1 of paddy seed. The most common weed contaminants in the seed samples were Oryza sativa f. spontanea (weedy rice), Fimbristylis miliacea, Echinochloa colona, Echinochloa crus-galli, and Ischaemum rugosum. Weeds, in their rice field, were considered a major problem by 93% of farmers with 70% of farmers indicating a yield loss of >20% due to weed competition. All farmers followed a post-emergence based herbicide program for weed control with no use of pre-emergence herbicides. Farmers (75%) relied on the advice of input dealers on the selection and use of herbicides. Knowledge gaps were found among farmers on herbicide application techniques including selection of the right sprayer, nozzle tips, and sprayer calibration. Although 94% of farmers responded that they were aware of pesticide exposure risk, use of boots and gloves, as personal protective equipment, during spraying was low (10 and 54%, respectively). The fertilizer use was lower than recommended rates (50% of recommended N and around 40% of recommended P and K). An exploitable rice yield gap of 1.3 t ha−1 (40%) and 1.1 t ha−1 (30%) was found in the wet and dry season, respectively. These results suggest that integrated weed management (IWM) and optimum fertilizer use can play an important role in closing the rice yield gap in Battambang. IWM options using clean/certified seeds free from weed seeds, optimum fertilizer, selection and application of appropriate pre- and post-emergence herbicides at the right time, amount, and accurate application techniques can improve weed control and hence enhance the rice yield in Cambodia. Farmer training is needed to close their knowledge gaps and to educate them on IWM, especially, to manage difficult-to-control weeds such as weedy rice.

    更新日期:2020-01-04
  • Combining partial host resistance with bacterial biocontrol agents improves outcomes for tomatoes infected with Ralstonia pseudosolanacearum
    Crop Prot. (IF 2.172) Pub Date : 2019-04-04
    Nagendra Subedi; Christopher G. Taylor; Pierce A. Paul; Sally A. Miller

    We selected six strains with in vitro antagonism against 15 South Asian strains of Ralstonia pseudosolanacearum from among 54 previously characterized Pseudomonas and other bacterial biocontrol strains and evaluated the value of integration of these biocontrol agents with partial host resistance of tomato in management of bacterial wilt. Biocontrol strains were almost four times more effective in suppressing bacterial wilt in IRAT L3, a partially resistant tomato line, than in L390, a highly susceptible line. Pseudomonas brassicacearum 93D8 and Wood 1R, and P. fluorescens Clinto 1 were the most effective strains with biocontrol efficacy of 68, 47 and 56% respectively, in IRAT L3. Bacterial wilt incidence was suppressed in IRAT L3 in four of four experiments by P. brassicacearum 93D8, and in three of four experiments by P. protegens Clinto 1 and P. brassicacearum Wood 1R. However, in L390, biocontrol efficacy of P. brassicacearum 93D8 and Wood 1R, and P. fluorescens Clinto 1 was 7, 15 and 12%, respectively. There was no correlation between in vitro antagonism of the biocontrol strains against R. pseudosolanacearum and in vivo biocontrol efficacy. These results highlight the value of integration of biocontrol agents with host resistance in management of bacterial wilt.

    更新日期:2020-01-04
  • Modeling commodity flow in the context of invasive species spread: Study of Tuta absoluta in Nepal
    Crop Prot. (IF 2.172) Pub Date : 2019-02-25
    S. Venkatramanan; S. Wu; B. Shi; A. Marathe; M. Marathe; S. Eubank; L.P. Sah; A.P. Giri; L.A. Colavito; K.S. Nitin; V. Sridhar; R. Asokan; R. Muniappan; G. Norton; A. Adiga

    Trade and transport of goods is widely accepted as a primary pathway for the introduction and dispersal of invasive species. However, understanding commodity flows remains a challenge owing to its complex nature, unavailability of quality data, and lack of systematic modeling methods. A robust network-based approach is proposed to model seasonal flow of agricultural produce and examine its role in pest spread. It is applied to study the spread of Tuta absoluta, a devastating pest of tomato in Nepal. Further, the long-term establishment potential of the pest and its economic impact on the country are assessed. Our analysis indicates that regional trade plays an important role in the spread of T. absoluta. The economic impact of this invasion could range from USD 17–25 million. The proposed approach is generic and particularly suited for data-poor scenarios.

    更新日期:2020-01-04
  • Challenges and prospects for weed management in Pakistan: A review
    Crop Prot. (IF 2.172) Pub Date : 2019-02-07
    Amar Matloob; Muhammad Ehsan Safdar; Tasawer Abbas; Farhena Aslam; Abdul Khaliq; Asif Tanveer; Abdul Rehman; Asim Raza Chadhar

    Weed management has become increasingly important in the backdrop of sustainable crop production, uncertain climatic patterns and food security concerns in Pakistan. Due to diverse agro-climatic conditions, 267 weed species have been identified to be responsible for causing monetary loss worth 3 billion USD annually. Weed competition for resources, interference with crops, weed-related increased incidence of pests and diseases in different crops, and high management costs incurred in controlling weeds make weed management a critical task for the farmers. Moreover, herbicide resistant weeds, labor shortage, higher wages, weed population shifts, changing climatic optima, unavailability of proper and timely inputs, ever increasing threats of invasive weeds, lack of knowledge and training regarding herbicides, and the poor financial resources of the small land holders are major hurdles towards effective weed management in Pakistan. These multi-dimensional problems need holistic line of action with multi-disciplinary collaboration. Improved knowledge of weed ecology, biology, genetics and molecular biology is essential for developing sustainable weed control practices. Some advances are already commercialized, and others are in the process of development. Advancements like vision guided machines for site-specific weed management, recognition and application modules, development of air inclusion nozzles, nanoherbicides, water based formulations with fewer hydrocarbons, herbicide-resistant transgenic crops, robotics to monitor and spray weeds, decision support systems and predictive modeling can be adopted to foster modern weed management in the country. Various conventional weed management approaches like narrow row spacing, row orientation, increased crop density, use of cover crops, intercropping, development of weed-competitive crop cultivars, and their integration can help reduce herbicide input under a given scenario. There is dire need to establish regional weed research institutes under various cropping systems to carry out strategic and applied research in weed science. Innovative teaching and training practices are needed to tackle complex weed management challenges. Effective linkages between academia-research-industry-extension services could play a pivotal role to reframe technological advancements and legislation and to advocate innovations to the farmers. Capacity building, more research fund allocation, and reorienting educational system seem indispensable. Here, we have presented a broad review to summarize the current state of knowledge about the problems and prospects of sustainable weed management approaches in Pakistan. Advanced weed management approaches keeping in view the local agro-ecological conditions have also been discussed in this review to improve the scientific knowledge so that the discipline gets stronger and more focused than ever before.

    更新日期:2020-01-04
  • Validation of a bio-based integrated pest management package for the control of major insect pests on Chinese mustard in Cambodia
    Crop Prot. (IF 2.172) Pub Date : 2019-02-07
    Srinivasan Ramasamy; Paola Sotelo; Mei-ying Lin; Chhun Hy Heng; Sareth Kang; Sor Sarika

    Chinese mustard is an important leafy vegetable, which is grown in about 5% of total vegetable area in major vegetable producing provinces of Cambodia. Production of Chinese mustard is severely hampered by the insect pests especially lepidopteran caterpillars and the flea beetles. Chinese mustard producers predominantly rely on the application of chemical pesticides for management of these pests and produce blemish free produce. In order to reduce the extensive reliance on pesticides, efficacy of biopesticides (Bacillus thuringiensis and Metarhizium anisopliae formulations, and neem extract), either alone and in combination (as an IPM package) against diamondback moth, common armyworm, cabbage webworm and striped flea beetle on Chinese mustard was assessed in three different provinces of Cambodia during 2015–2018. The bio-pesticides reduced the incidence of diamondback moth, common armyworm, cabbage webworm and the damage by striped flea beetle to the levels equivalent to chemical pesticide (abamectin) during trials in 2015 and 2016. Although the yield was significantly higher in bio-pesticide treated plots than untreated plots in 2015, the yield did not differ among the treatments in 2016 trials. Multi-location trials during 2016–2018 confirmed that the performance of the bio-based IPM package was on par with farmers’ practice of calendar-based pesticide application in reducing the damages by target pests, leading to significant yield gains. Hence, the bio-based IPM package can be a better alternative to chemical pesticides in managing the key insect pests on Chinese mustard in Cambodia.

    更新日期:2020-01-04
  • Tailor-made solutions to tackle rodent pests of rice through community-based management approaches in Cambodia
    Crop Prot. (IF 2.172) Pub Date : 2019-01-25
    Alexander M. Stuart; Parameas Kong; Rathmuny Then; Rica Joy Flor; Khay Sathya

    Rodents are a major pest of rice throughout Southeast Asia, causing both pre- and post-harvest losses. In Cambodia, where 90% of the cultivated land is used for rice production, rodent damage to rice can cause significant impacts to smallholder farmers’ livelihoods and to food security. To help smallholder farmers minimize yield losses from rodent pests, adaptive research experiments were established in two villages in Takeo province. In each village, three replicate 5-ha sites were selected for treatment and three for control. In each treatment site, groups of farmers implemented ecologically-based rodent management (EBRM) methods over two rice cropping seasons. The management methods were adapted based on the local situation and preferred practices of farmers and included maintaining basic hygiene in field margins, synchronous planting of rice crops, community rat hunts, no electric fencing and the implementation of a Community Trap Barrier System (CTBS) along with a Linear Trap Barrier System (LTBS) in an area of intensive rice monoculture, and a LTBS with targeted and limited bromadiolone rodenticide in an area growing recession rice on lake margins. Over 130 rats were caught at each treatment site per season and rodent damage levels were reduced from a mean of 22–34% per site and season in the non-treatment sites to less than 6% in the treatment sites. Following the implementation of EBRM, rice yields were, on average, 20–32% higher in the treatment sites than in the non-treatment sites, giving a 53–169% increase in net income and a benefit-cost ratio ranging from 3:1 to 11:1 per season. We show that rodent damage to rice in Cambodia and the associated yield loss can be significantly reduced following the implementation of cost-efficient EBRM approaches that were locally adapted to village-specific agro-ecological and social conditions. We conclude by discussing incentives that support the adoption of these practices by smallholder farming communities.

    更新日期:2020-01-04
  • Weed research status, challenges, and opportunities in China
    Crop Prot. (IF 2.172) Pub Date : 2018-03-05
    Jinwen Zhu; Jian Wang; Antonio DiTommaso; Chaoxian Zhang; Guiping Zheng; Wen Liang; Faisal Islam; Chong Yang; Xuexin Chen; Weijun Zhou

    Weeds are a major constraint to crop production, which is of crucial importance for food security in China given its 1.37 billion population. In recent years, an increasing number of herbicide resistant weeds and invasive alien plants have become prevalent and challenging to manage in China as elsewhere in the world. In this review, we provide an overview of several key facets of weed science research in China, including (i) weed community shifts as a result of cropping system and weed management changes, (ii) the status of invasive weeds, (iii) weed management options for the increasing number of herbicide resistant weeds, and (iv) the challenges and opportunities in weed research in China. Invasive weeds in tandem with changes in cropping systems have significantly altered weed communities in crops such as rice (Oryza sativa L.), wheat (Triticum aestivum L.), maize (Zea mays L.), soybean [Glycine max (L.) Merr.], cotton (Gossypium hirsutum L.), and oilseed rape (Brassica napus L.). At present, 30 weed species have evolved resistance to 11 herbicide sites of action that includes 48 commonly used herbicides. Although tactics such as crop rotation and biological control have been used to manage some weeds in China, weed control has and continues to rely primarily on herbicides. Research priorities for weed management include developing and implementing a preventive risk assessment framework and a better understanding of the mechanisms that allow some alien weeds to be highly aggressive and difficult to manage. Moreover, the development and evaluation of additional weed management tactics such as breeding competitive crop cultivars, straw mulching, optimizing water management, and site-specific fertilizer and herbicide applications warrant further study. The use of an integrated weed management approach in coming years will rely heavily on a more in-depth understanding of the biological and ecological principles governing weed population dynamics. Approaches such as herbicide resistance weed management (HRWM) programs in tandem with conservation agriculture (CA) can be employed to develop sustainable weed management strategies in cropping systems.

    更新日期:2020-01-04
  • Research issues, challenges, and opportunities for weed management in Japan
    Crop Prot. (IF 2.172) Pub Date : 2018-02-14
    Tohru Tominaga; Shunji Kurokawa

    This review states the outline of field crop production of Japan and weed problems to be solved. Field crop production of Japan is characterized by rice cultivation and small size farming. Most major field crops other than rice are imported, and various kinds and a very large amount of living weed seeds contaminate the imported grains. These alien weeds sometimes invade agricultural fields and cause serious losses of crop yields and reductions in the quality of agricultural products. Emergence of herbicide resistant biotypes of weeds, especially paddy weeds, is also issues to be solved. Weedy rice is recently emerging again due to the change of rice production system and the origin of recently emerging weedy rice is not clarified yet.

    更新日期:2020-01-04
  • Weed research issues, challenges, and opportunities in India
    Crop Prot. (IF 2.172) Pub Date : 2018-02-10
    A.N. Rao; Ravi Gopal Singh; Gulshan Mahajan; S.P. Wani

    Agriculture is the major source of livelihood for nearly half of the Indian population. However, the productivity of crops is much lower than many countries and needs enhancement to produce ∼400 million tons of food grains for meeting food demands of a population of 1.7 billion by 2050. Diverse climatic conditions in India favor the most adopted weeds to prevail and cause severe crop yield losses. Weeds also degrade quality of the produce, raise cost of production; harbor and serve as alternate hosts to several insect pests and diseases. Parthenium hysterophorus L.; Phalaris minor Retz.; Leptochloa chinensis (L.) Nees.; Echinochloa spp.; weedy rice; Lantana camara L.; Chromolaena odorata (L.) R.M. King & H. Rob.; Mikania micrantha Kunth., are a few of many major weeds of concern currently in India. Weed management in India is critical to improve crops productivity by minimizing weeds caused crop yield losses and to alleviate other adverse effects of weeds in different ecosystems. In spite of the progress made in evolving weed management technologies for different crops and other ecosystems, weeds continue to be a concern in varying ecosystems. The real challenges of Indian weed research are: managing weeds in small farms; non availability of labor and mechanical tools; inadequate information on weed biology and shifts in weed flora; herbicide resistant weeds; lack of understanding on the impact of climate change on weeds and weed control; popularizing integrated weed management with herbicides use by ensuring safe use to avoid adverse effect on human health, environment and avoid weeds developing herbicide resistance and prevention of entry and management of alien invasive weeds. The greatest opportunity of Indian weed science is the potentiality of appropriate weed management technologies to substantially improve the crops productivity. Thus, weed scientists have a greater role to play in the development, popularization and adoption of location specific effective, economical and eco-friendly weed management technologies for different ecosystems of India.

    更新日期:2020-01-04
  • Weed problems, challenges, and opportunities in Iran
    Crop Prot. (IF 2.172) Pub Date : 2017-10-26
    Iraj Nosratti; Peyman Sabeti; Gelareh Chaghamirzaee; Hassan Heidari

    Weeds are a serious threat to crop production in Iran as they reduce the yield of wheat, barley, rice, maize, and chickpea on average by 23%, 21%, 35%, 20%, and 50%, respectively. Orobanche spp., Avena ludoviciana (Durieu.), Convolvulus arvensis (L.), Sorghum halpence (L.) Pers, and Cuscuta compestris (Y.) are the most important weed species that compete with major crops in Iran. Recently, some newly introduced and invasive weeds, including Hordeum spontaneum (K. Koch.), Cynanchum acutum (L.), Physalis divaricata (L.), and Azolla filiculoides (Lam.), have become a very serious problem in a wide range of crops in different parts of Iran. Chemical control is the predominant weed management practice in Iran. In addition, mechanical weed control methods including soil tillage and hand weeding are applied to a lesser extent. 2,4-D + MCPA (in cereal crops), clodinafop-propargyl (in wheat crop), haloxyfop-r-methyl ester (in broadleaved crops), tribenuron-methyl (in wheat), nicosulfuron (in maize), trifluralin (in oil crops), metribuzin (in potato), glyphosate (in orchards and non-cultivated areas), and paraquat (in waste lands and between crop rows) are the most commonly used herbicides in Iran. There are currently 14 unique cases (species x site of action) of herbicide-resistant weeds in Iran. The most important and newly emerged challenges in Iran are to manage the present noxious and invasive weed species. Increasingly, the evolution of herbicide-resistant biotypes in wheat and other important crops would be another challenge in the future. In addition, the adoption and extension of integrated weed management strategy, addition of suitable adjuvants to herbicide tank mixture, and use of proper sprayers would remain critical challenges in weed management practices in Iran. The integration of weed control methods such as crop rotation, tillage, planting date and pattern, herbicides, and allelopathy would lead to the effective and sustainable management of weeds.

    更新日期:2020-01-04
  • Weed management issues, challenges, and opportunities in Malaysia
    Crop Prot. (IF 2.172) Pub Date : 2017-09-18
    Masilamany Dilipkumar; Tse Seng Chuah; Sou Sheng Goh; Ismail Sahid

    The agriculture sector remains a significant development factor in Malaysia. Oil palm and rubber are the two major crops contributing to national development in terms of export earnings, and rice is vital for the national food consumption. However, weeds continue to be an important constraint for oil palm, rubber, and rice production. Weed management in Malaysia is highly reliant on herbicides; however, other control measures are integrated, including cultural, physical, biological, and mechanical methods. Thus, herbicides accounted for 83% of the total pesticide usage in the year 2014. However, several limitations remain in weed control and these are influenced by several factors, such as labour shortage, evolution of herbicide resistance in weeds, constraints of new modern technology implementation, global climate change, poor policy support, inadequate infrastructure, and rising input costs. This paper explains a number of issues, challenges, and opportunities that are significant for the future role of weed management in the agriculture of Malaysia, especially for the oil palm, rubber, and rice industries.

    更新日期:2020-01-04
  • Weed research issues, challenges, and opportunities in Cambodia
    Crop Prot. (IF 2.172) Pub Date : 2017-07-10
    Robert J. Martin

    The area of cultivated agricultural land in Cambodia is 3.7 million hectares with 76% of this planted to lowland rice and 24% planted to upland crops such as cassava, maize, soybean, sugar cane and vegetables. Cambodia's average rice paddy yield at around 3 t ha−1 is around 50% of the yield potential and losses caused by weed competition have been shown to be a significant constraint. The most important issues currently affecting weed management in Cambodia's cropping systems are (a) increased climate variability and climate change, and (b) migration of labour from the rural workforce and consequent rapid mechanisation of agriculture. As a result of climate change, the wet season in Cambodia now begins and ends approximately one month later, and the bimodal rainfall distribution has strengthened, resulting in more extreme events of drought and flood during the wet season. A decline in the availability of agricultural labour has resulted in rapid mechanisation of land preparation, broadcast seeding, herbicide use and machine harvesting of rice and these changes have had significant repercussions for weed management. The resultant challenges and opportunities for weed management are presented and discussed. The main weed management challenges are associated with rice crop intensification, transition from transplanting to direct-seeded rice, changed planting dates and tillage practices in response to climate change, over-reliance on post-emergence herbicides, excessive inversion tillage, and lack of knowledge about the safe and efficacious use of herbicides. Opportunities for improved weed management in Cambodia's cropping systems include the development of integrated weed management for double crop intensive rice systems, transition from hand broadcasting to drill-seeded rice, new seeding windows and minimum tillage, non-transgenic herbicide resistant crops and education and training of input sellers and farmers to improve safety and efficacy of herbicide use.

    更新日期:2020-01-04
  • Weed research issues, challenges, and opportunities in Bhutan
    Crop Prot. (IF 2.172) Pub Date : 2017-06-09
    Sangay Tshewang; Chezang Dendup; Pasang Tshering; Paul Kristiansen

    Rice, maize and wheat account for 96% of the total food grain production in Bhutan signifying their importance for food security and the socioeconomic value of the Bhutanese agriculture. However, various biotic and abiotic factors impede optimum production of these cereals with weeds as one the main biotic constraints in attaining the full realisation of potential yields. In Bhutan, weeds have the potential to cause rice yield loss up to 50%. Similarly, 50% of the labour in maize production is for hand weeding. Key challenges for weeds management are labour availability, small farm sizes and potential risks of developing herbicide resistance from unsuitable usage patterns. Currently, rice is the only crop which receives herbicide, with long-term usage of a single chemical, butachlor. Manual weeding continues to be the main form of weed management in rice and maize, though the effectiveness of herbicide in maize has been demonstrated. Wheat is currently un-weeded, and no chemicals are used. Developing alternative herbicides to butachlor with different modes of action, and providing training on proper usage are likely to become more important. Considering the existing wide-spread use of low-external-input farming systems in Bhutan, non-chemical tactics will continue to have a key role in weed management. Some of these methods include competitive cultivars, optimum planting configurations, intercropping and strategic agronomic management. Incorporating these into an integrated package that includes herbicides may have long-term benefits for farmers.

    更新日期:2020-01-04
  • Economic benefits of blast-resistant biofortified wheat in Bangladesh: The case of BARI Gom 33.
    Crop Prot. (IF 2.172) Pub Date : 2019-09-05
    Khondoker A Mottaleb,Velu Govindan,Pawan K Singh,Kai Sonder,Xinyao He,Ravi P Singh,Arun K Joshi,Naresh C D Barma,Gideon Kruseman,Olaf Erenstein

    The first occurrence of wheat blast in 2016 threatened Bangladesh's already precarious food security situation. The Bangladesh Agricultural Research Institute (BARI), together with the International Maize and Wheat Improvement Center (CIMMYT) developed and released the wheat variety BARI Gom 33 that is resistant to wheat blast and other common diseases. The new variety provides a 5-8% yield gain over the available popular varieties, as well as being zinc enriched. This study examines the potential economic benefits of BARI Gom 33 in Bangladesh. First, applying a climate analogue model, this study identified that more than 55% of the total wheat-growing area in Bangladesh (across 45 districts) is vulnerable to wheat blast. Second, applying an ex-ante impact assessment framework, this study shows that with an assumed cumulative adoption starting from 2019-20 and increasing to 30% by 2027-28, the potential economic benefits of the newly developed wheat variety far exceeds its dissemination cost by 2029-30. Even if dissemination of the new wheat variety is limited to only the ten currently blast-affected districts, the yearly average net benefits could amount to USD 0.23-1.6 million. Based on the findings, international funder agencies are urged to support the national system in scaling out the new wheat variety and wheat research in general to ensure overall food security in Bangladesh and South Asia.

    更新日期:2019-11-01
  • Primary hexaploid synthetics: Novel sources of wheat disease resistance.
    Crop Prot. (IF 2.172) Pub Date : 2019-07-06
    Vladimir Shamanin,Sergey Shepelev,Violetta Pozherukova,Elena Gultyaeva,Tamara Kolomiets,Elena Pakholkova,Alexey Morgounov

    Climate change is leading to increased occurrence of and yield losses to wheat diseases. Managing these diseases by introducing new, effective and diverse resistance genes into cultivars represents an important component of sustainable wheat production. In 2016 and 2017 a set of primary hexaploid synthetic wheat was studied under high disease pressure: powdery mildew, leaf and stem rust in Omsk; Septoria tritici and S. nodorum in Moscow. A total of 28 synthetics (19 CIMMYT synthetics and 9 Japanese synthetics) were selected as having combined resistance to at least two diseases in both years of testing. Two synthetics (entries 13 and 18) originating from crosses between winter durum wheat Ukrainka odesskaya-1530.94 and various Aegilopes taushii accessions, and four synthetics (entries 20, 21, 23 and 24) from cross between Canadian durum wheat Langdon and Ae. taushii were resistant to all four pathogens. Pathological and molecular markers evaluation of resistance suggests presence of new genes and diverse types of resistance. The novel genetic sources of disease resistance identified in this study can be successfully utilized in wheat breeding.

    更新日期:2019-11-01
  • Evaluation of cowpea (Vigna unguiculata (L.) Walp.) landraces to bacterial blight caused by Xanthomonas axonopodis pv. vignicola.
    Crop Prot. (IF 2.172) Pub Date : 2019-04-23
    Hammed A Durojaye,Yonnelle D Moukoumbi,Victor O Dania,Ousmane Boukar,Ranajit Bandyopadhyay,Alejandro Ortega-Beltran

    Cowpea is an important protein source for human populations in many nations across sub-Saharan Africa (SSA). However, cowpea production is constrained by bacterial blight (CoBB) caused by Xanthomonas axonopodis pv. vignicola (Xav), a disease affecting most cowpea-growing areas. A large proportion of smallholder farmers across SSA rely on traditional cowpea landraces (CLR) to produce the crop. The International Institute of Tropical Agriculture (IITA) possesses the largest collection of cowpea germplasm, including several CLR accessions. However, screening for resistance to CoBB in most of the CLR accessions maintained at IITA has not been conducted. CoBB severity was evaluated in 103 CLR accessions from five African countries, the US, The Philippines, and Sri Lanka by artificially inoculating a highly virulent Xav strain in plants grown in a screenhouse. Highly significant (P < 0.0001) differences in susceptibilities to the disease were detected among the evaluated germplasm. Resistance was detected in several CLR accessions with two accessions from Nigeria and one from the US developing no disease symptoms. Our results indicate that several CLR accessions are valuable sources of resistance to CoBB and those could be used to breed for improved varieties with superior resistance to the disease. The resistant CLR accessions and others in IITA collection should be further investigated to identify additional beneficial traits that may contribute to the development of improved, commercially acceptable varieties.

    更新日期:2019-11-01
  • Resistance of advanced cassava breeding clones to infection by major viruses in Uganda.
    Crop Prot. (IF 2.172) Pub Date : 2019-02-12
    Daniel Rogers Mukiibi,Titus Alicai,Robert Kawuki,Geoffrey Okao-Okuja,Fred Tairo,Peter Sseruwagi,Joseph Ndunguru,Elijah Miinda Ateka

    Cassava brown streak disease (CBSD) and cassava mosaic disease (CMD) are two viral diseases that cause severe yield losses in cassava of up to 100%, thereby persistently threatening food and income security in sub-Saharan Africa. For effective management of these diseases, there is a critical need to develop and deploy varieties with dual resistance to CBSD and CMD. In this study, we determined the response of advanced breeding lines to field infection by cassava brown streak viruses (CBSVs) and cassava mosaic begomoviruses (CMBs). This aim helped in identifying superior clones for downstream breeding. In total, 220 cassava clones, three in uniform yield trials (UYTs) and 217 in a crossing block trial (CBT), were evaluated for virus and disease resistance. Field data were collected on disease incidence and severity. To detect and quantify CBSVs, 448 and 128 leaf samples from CBSD symptomatic and symptomless plants were analyzed by reverse transcription PCR and real-time quantitative PCR, respectively. In addition, 93 leaf samples from CMD symptomatic plants in the CBT were analyzed by conventional PCR using CMB species-specific primers. In the CBT, 124 (57%) cassava clones did not express CMD symptoms. Of the affected plants, 44 (55%) had single African cassava mosaic virus infection. Single Cassava brown streak virus (CBSV) infections were more prevalent (81.6%) in CBT clones than single Ugandan cassava brown streak virus (UCBSV) infection (3.2%). Of the three advanced clones in the UYT, NAROCASS 1 and NAROCASS 2 had significantly lower (P < 0.05) CBSD severity, incidence, and CBSV load than MH04/0300. In the UYT, only 22% of samples tested had CBSVs, and all showed a negative result for CMBs. The low disease incidence, severity, and viral load associated with NAROCASS 1 and NAROCASS 2 is evidence of their tolerance to both CBSD and CMD. Therefore, these two cassava clones should be utilized in CBSD and CMD management in Uganda, including their utilization as progenitors in further virus resistance breeding.

    更新日期:2019-11-01
  • Unanticipated benefits and potential ecological costs associated with pyramiding leafhopper resistance loci in rice.
    Crop Prot. (IF 2.172) Pub Date : 2019-02-12
    Finbarr G Horgan,Maria-Liberty P Almazan,Quynh Vu,Angelee Fame Ramal,Carmencita C Bernal,Hideshi Yasui,Daisuke Fujita

    We tested the hypotheses that increasing the number of anti-herbivore resistance loci in crop plants will increase resistance strength, increase the spectrum of resistance (the number of species affected), and increase resistance stability. We further examined the potential ecological costs of pyramiding resistance under benign environments. In our experiments, we used 14 near-isogenic rice lines with zero (T65: recurrent parent), one, two or three resistance loci introgressed through marker-assisted selection. Lines with two or more loci that were originally bred for resistance to the green rice leafhopper, Nephotettix cincticeps, significantly reduced egg-laying by the green leafhopper, N. virescens. Declines in egg-number and in nymph weight were correlated with the numbers of resistance loci in the rice lines. To test the spectrum of resistance, we challenged the lines with a range of phloem feeders including the zig-zag leafhopper, Recilia dorsalis, brown planthopper, Nilaparvata lugens, and whitebacked planthopper, Sogatella furcifera. There was an increase in the number of tested species showing significant declines in egg-laying and nymph survival on lines with increasing numbers of loci. In a screen house trial that varied rates of nitrogenous fertilizer, a line with three loci had stable resistance against the green leafhopper and the grain yields of infested plants were maintained or increased (overcompensation). Under benign conditions, plant growth and grain yields declined with increasing numbers of resistance loci. However, under field conditions with natural exposure to herbivores, there were no significant differences in final yields. Our results clearly indicate the benefits, including unanticipated benefits such as providing resistance against multiple herbivore species, of pyramiding anti-herbivore resistance genes/loci in crop plants. We discuss our results as part of a review of existing research on pyramided resistance against leafhoppers and planthoppers in rice. We suggest that potential ecological costs may be overcome by the careful selection of gene combinations for pyramiding, avoidance of high (potentially redundant) loci numbers, and introgression of loci into robust plant types such as hybrid rice varieties.

    更新日期:2019-11-01
  • Increased yield stability of field-grown winter barley (Hordeum vulgare L.) varietal mixtures through ecological processes.
    Crop Prot. (IF 2.172) Pub Date : 2016-07-05
    Henry E Creissen,Tove H Jorgensen,James K M Brown

    Crop variety mixtures have the potential to increase yield stability in highly variable and unpredictable environments, yet knowledge of the specific mechanisms underlying enhanced yield stability has been limited. Ecological processes in genetically diverse crops were investigated by conducting field trials with winter barley varieties (Hordeum vulgare), grown as monocultures or as three-way mixtures in fungicide treated and untreated plots at three sites. Mixtures achieved yields comparable to the best performing monocultures whilst enhancing yield stability despite being subject to multiple predicted and unpredicted abiotic and biotic stresses including brown rust (Puccinia hordei) and lodging. There was compensation through competitive release because the most competitive variety overyielded in mixtures thereby compensating for less competitive varieties. Facilitation was also identified as an important ecological process within mixtures by reducing lodging. This study indicates that crop varietal mixtures have the capacity to stabilise productivity even when environmental conditions and stresses are not predicted in advance. Varietal mixtures provide a means of increasing crop genetic diversity without the need for extensive breeding efforts. They may confer enhanced resilience to environmental stresses and thus be a desirable component of future cropping systems for sustainable arable farming.

    更新日期:2019-11-01
  • Pesticides use by smallholder farmers in vegetable production in Northern Tanzania.
    Crop Prot. (IF 2.172) Pub Date : 2008-06-06
    A V F Ngowi,T J Mbise,A S M Ijani,L London,O C Ajayi

    Small-scale farmers in Northern Tanzania grow vegetables that include tomatoes, cabbages and onions and use many types of pesticides to control pests and diseases that attack these crops. Based on the use of questionnaires and interviews that were conducted in Arumeru, Monduli, Karatu, and Moshi rural districts, this study investigates farmers' practices on vegetable pest management using pesticides and related cost and health effects. The types of pesticides used by the farmers in the study areas were insecticides (59%), fungicides (29%) and herbicides (10%) with the remaining 2% being rodenticides. About a third of the farmers applied pesticides in mixtures. Up to 90% had a maximum of 3 pesticides in a mixture. In all cases there were no specific instructions either from the labels or extension workers regarding these tank mixtures. Fifty three percent of the farmers reported that the trend of pesticide use was increasing, while 33% was constant and 14% was decreasing. More than 50 percent of the respondents applied pesticides up to 5 times or more per cropping season depending on the crop. Insecticides and fungicides were routinely applied by 77% and 7%, respectively by these farmers. Sixty eight percent of farmers reported having felt sick after routine application of pesticides. Pesticide-related health symptoms that were associated with pesticides use included skin problems and neurological system disturbances (dizziness, headache). Sixty one percent of farmers reported spending no money on health due to pesticides. These results can be used to develop a tool to quantify the cost of pesticide use in pest management by small-scale vegetable farmers in Northern Tanzania and contribute to the reformation of pesticide policy for safe and effective use of pesticides.

    更新日期:2019-11-01
  • Virulence adaptation in a rice leafhopper: Exposure to ineffective genes compromises pyramided resistance.
    Crop Prot. (IF 2.172) Pub Date : 2018-11-06
    Finbarr G Horgan,Carmencita C Bernal,Quynh Vu,Maria Liberty P Almazan,Angelee Fame Ramal,Hideshi Yasui,Daisuke Fujita

    Pyramiding resistance genes is predicted to increase the durability of resistant rice varieties against phloem-feeding herbivores. We examined responses by the green leafhopper, Nephotettix virescens (Hemiptera: Cicadellidae), to near-isogenic rice lines with zero, one and two resistance genes. The recurrent parent (T65) and monogenic lines (GRH2-NIL and GRH4-NIL) with genes for resistance to the green rice leafhopper, Nephotettix cincticeps (Hemiptera: Cicadellidae), were susceptible to the green leafhopper, but the pyramided line (GRH2/GRH4-PYL) was highly resistant to the green leafhopper. We selected green leafhoppers, N. virescens, from five sites in the Philippines for over 20 generations on each of the four lines. Populations selected on GRH2/GRH4-PYL gained partial virulence (feeding and development equal to that on T65) to the pyramided line within 10 generations and complete virulence (egg-laying equal to that on T65) within 20 generations. After 20 generations of rearing on the susceptible monogenic lines, green leafhoppers were also capable of developing and laying eggs on GRH2/GRH4-PYL. Furthermore, green leafhoppers reared on the susceptible GRH4-NIL for 20 generations showed equal preferences for T65 and GRH2/GRH4-PYL in choice bioassays. Our results indicate that previous long-term exposure to ineffective genes (including unperceived resistance genes) could dramatically reduce the durability of pyramided resistance. We suggest that informed crop management and deployment strategies should be developed to accompany rice lines with pyramided resistance and avoid the build-up of virulent herbivore populations.

    更新日期:2019-11-01
  • Plot based heritability estimates and categorization of cassava genotype response to cassava brown streak disease.
    Crop Prot. (IF 2.172) Pub Date : 2018-06-05
    A Okul Valentor,M Ochwo-Ssemakula,T Kaweesi,A Ozimati,E Mrema,E S Mwale,P Gibson,E Achola,R Edema,Y Baguma,R Kawuki

    Cassava brown streak disease (CBSD) caused by Cassava brown streak virus (CBSV) and Ugandan cassava brown streak virus (UCBSV) is a threat to food security in sub-Saharan Africa, where the disease persistently reduces overall root quality and quantity resulting in up to 100% yield losses. Complexities in CBSD symptom expression and the damage caused on leaves, stems and roots throughout the 12 months of cassava growth require that appropriate ways of categorizing genotype response and optimal stages of evaluation be identified. This study aimed at: 1) determining plot based heritability of CBSD based on symptom expression and 2) categorizing genotype resistance to CBSD based on symptom expression. Herein, 41 genotypes were evaluated for two years at Namulonge with an additional evaluation conducted across three locations. Evaluations were done at three, six, nine and twelve months after planting. Genotype responses to CBSD varied significantly. High broad sense heritability estimates of up to 0.81 (incidence) and 0.71 (severity) were obtained. Average disease severity scores had higher broad sense heritability estimates (0.53 and 0.65) than maximum disease severity scores (0.33 and 0.61) for root and foliar severities respectively. These findings are important in choosing an appropriate evaluation method for CBSD. Genotypes displayed differing CBSD responses in type, locality and severity of symptoms. This suggested that genotypes had differences in mechanisms of resistance that can be exploited in CBSD resistance breeding.

    更新日期:2019-11-01
  • Drought-tolerant Desmodium species effectively suppress parasitic striga weed and improve cereal grain yields in western Kenya.
    Crop Prot. (IF 2.172) Pub Date : 2017-08-05
    Charles A O Midega,Charles J Wasonga,Antony M Hooper,John A Pickett,Zeyaur R Khan

    The parasitic weed Striga hermonthica Benth. (Orobanchaceae), commonly known as striga, is an increasingly important constraint to cereal production in sub-Saharan Africa (SSA), often resulting in total yield losses in maize (Zea mays L.) and substantial losses in sorghum (Sorghum bicolor (L.) Moench). This is further aggravated by soil degradation and drought conditions that are gradually becoming widespread in SSA. Forage legumes in the genus Desmodium (Fabaceae), mainly D. uncinatum and D. intortum, effectively control striga and improve crop productivity in SSA. However, negative effects of climate change such as drought stress is affecting the functioning of these systems. There is thus a need to identify and characterize new plants possessing the required ecological chemistry to protect crops against the biotic stress of striga under such environmental conditions. 17 accessions comprising 10 species of Desmodium were screened for their drought stress tolerance and ability to suppress striga. Desmodium incanum and D. ramosissimum were selected as the most promising species as they retained their leaves and maintained leaf function for longer periods during their exposure to drought stress conditions. They also had desirable phenotypes with more above ground biomass. The two species suppressed striga infestation, both under controlled and field conditions, and resulted in significant grain yield increases, demonstrating the incremental capability of Desmodium species in striga suppression. These results demonstrate beneficial effects of Desmodium species in enhancing cereal productivity in dry areas.

    更新日期:2019-11-01
  • Using simulation models to investigate the cumulative effects of sowing rate, sowing date and cultivar choice on weed competition.
    Crop Prot. (IF 2.172) Pub Date : 2017-05-05
    Izzadora K S Andrew,Jonathan Storkey

    With the increasing pressure on crop production from the evolution of herbicide resistance, farmers are increasingly adopting Integrated Weed Management (IWM) strategies to augment their weed control. These include measures to increase the competitiveness of the crop canopy such as increased sowing rate and the use of more competitive cultivars. While there are data on the relative impact of these non-chemical weed control methods assessed in isolation, there is uncertainty about their combined contribution, which may be hindering their adoption. In this article, the INTERCOM simulation model of crop/weed competition was used to examine the combined impact of crop density, sowing date and cultivar choice on the outcomes of competition between wheat (Triticum aestivum) and Alopecurus myosuroides. Alopecurus myosuroides is a problematic weed of cereal crops in North-Western Europe and the primary target for IWM in the UK because it has evolved resistance to a range of herbicides. The model was parameterised for two cultivars with contrasting competitive ability, and simulations run across 10 years at different crop densities and two sowing dates. The results suggest that sowing date, sowing density and cultivar choice largely work in a complementary fashion, allowing enhanced competitive ability against weeds when used in combination. However, the relative benefit of choosing a more competitive cultivar decreases at later sowing dates and higher crop densities. Modeling approaches could be further employed to examine the effectiveness of IWM, reducing the need for more expensive and cumbersome long-term in situ experimentation.

    更新日期:2019-11-01
  • Resistance of Bt-maize (MON810) against the stem borers Busseola fusca (Fuller) and Chilo partellus (Swinhoe) and its yield performance in Kenya.
    Crop Prot. (IF 2.172) Pub Date : 2016-11-05
    Tadele Tefera,Stephen Mugo,Murenga Mwimali,Bruce Anani,Regina Tende,Yoseph Beyene,Simon Gichuki,Sylvester O Oikeh,Francis Nang'ayo,James Okeno,Evans Njeru,Kiru Pillay,Barbara Meisel,B M Prasanna

    A study was conducted to assess the performance of maize hybrids with Bt event MON810 (Bt-hybrids) against the maize stem borer Busseola fusca (Fuller) in a biosafety greenhouse (BGH) and against the spotted stem borer Chilo partellus (Swinhoe) under confined field trials (CFT) in Kenya for three seasons during 2013-2014. The study comprised 14 non-commercialized hybrids (seven pairs of near-isogenic Bt and non-Bt hybrids) and four non-Bt commercial hybrids. Each plant was artificially infested twice with 10 first instar larvae. In CFT, plants were infested with C. partellus 14 and 24 days after planting; in BGH, plants were infested with B. fusca 21 and 31 days after planting. In CFT, the seven Bt hybrids significantly differed from their non-Bt counterparts for leaf damage, number of exit holes, percent tunnel length, and grain yield. When averaged over three seasons, Bt-hybrids gave the highest grain yield (9.7 t ha-1), followed by non-Bt hybrids (6.9 t ha-1) and commercial checks (6 t ha-1). Bt-hybrids had the least number of exit holes and percent tunnel length in all the seasons as compared to the non-Bt hybrids and commercial checks. In BGH trials, Bt-hybrids consistently suffered less leaf damage than their non-Bt near isolines. The study demonstrated that MON810 was effective in controlling B. fusca and C. partellus. Bt-maize, therefore, has great potential to reduce the risk of maize grain losses in Africa due to stem borers, and will enable the smallholder farmers to produce high-quality grain with increased yield, reduced insecticide inputs, and improved food security.

    更新日期:2019-11-01
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