Control of Alternaria leaf blight caused by Alternaria alternata on sunflower using fungicides and Bacillus amyloliquefaciens
Introduction
Sunflower (Helianthus annuus L.) is a member of the Asteraceae; a large family of flowering plants occurring worldwide (Weiss, 1983). In South Africa, an average of 600000 tons of sunflower grain is produced annually since 2001, mainly in the North West, Free State, Mpumalanga and Limpopo provinces (ARC-ZAR, 2018). Alternaria leaf blight (ALB) of sunflower has been reported to cause up to 80% reduction in yield by causing head rot, seedling and leaf blight (Allen et al., 1983; Lapagodi, and Thanassoulopoulos, 1998; Calvet et al., 2005). Alternaria alternata (Fries) Kiessler has been recently found to be the predominant species in the major production fields of South Africa during recent sunflower disease surveys causing ALB (Kgatle et al., 2019).
Alternaria leaf blight of sunflower is characterised by irregular dark, necrotic lesions with a greyish brown centre surrounded by a chlorotic halo on the leaves, stem, petioles and capitulum (Kim and Mathur, 2006). In severe infections, lesions become larger by coalescing, leading to defoliation and death of plants (Cho and Yu, 2000), resulting in a decline in the photosynthetic area that adversely affects the growth and yield of the plant (Calvet et al., 2005). In addition to leaf blight, seed infection by Alternaria species can result in reduction in seed production and seed germination (Prasad et al., 2009). Moreover, seedlings germinating from Alternaria infected seed are often blighted and may serve as the initial source of inoculum in the field (van den Berg, 2001).
The use of resistant cultivars is normally the most economical management option available against most plant diseases, unfortunately, such resistance against ALB is not usually expressed in commercially available sunflower hybrids (Mesta et al., 2011) and many other crops (Iacomi-Vasilescu et al., 2004). Other methods for managing ALB disease on other crops are based on cultural practices such as using disease-free seeds and crop rotation together with commercial fungicides (Iacomi-Vasilescu et al., 2004; Avenot et al., 2008). Fungicides, used as both seed and spray treatments, include Iprodione, Mancozeb, Carbendazim (Karuna et al., 2012), Ridomil MZ (Khan et al., 2007), Chlorothalonil (Kumar et al., 2013), Captan (Swart et al., 1998) and strobilurin based fungicides (pyraclostrobin and Amistar®) (Horsfield et al., 2010).
There are currently no registered fungicides for the control of ALB on sunflower. This study aimed to determine the efficacy of five seed treatment fungicides, three spray fungicides and a biological control agent against ALB in three seed treatment and three fungicide spray program trials. The rational was to find a broad spectrum of fungicides that can control ALB of sunflower, with the aim of integrating these fungicides with other cultural ALB disease management practices.
Section snippets
Production practices
Field trials were conducted during the 2013/14, 2014/15 and 2015/16 growing seasons at the experimental site of the Agricultural Research Council-Grain Crops Institute in Potchefstroom which is situated at 26.745°S, 27.083°E, 1322 m above sea level in the North West province, South Africa. In each respective growing season, one seed treatment and one spray program trial was conducted.
Conventional cultural practices of commercial fields were used, which included a standard application of
Results
In all three seasons, sporadic initial ALB symptoms were observed on the cotyledons from 3 to 4 weeks after emergence in the fields in the seed treatment trials, mostly notable on the untreated control.
Discussion
Alternaria leaf blight disease severity has been negatively correlated with yield and has been known to significantly reduce head diameter, number of seeds produced per head, 1000-seed weight and percentage oil content (Lapagodi, and Thanassoulopoulos, 1998). To date little research has been done in South Africa to evaluate fungicide treatments for the control of ALB of sunflower. Thus, seed treatment field trials (consisting of a biological control agent and five fungicides) and spray program
Ethics statement
This statement confirms that the work submitted to this journal has not been submitted elsewhere for publication, has not been published or accepted for publication, nor is being considered for publication elsewhere (either in whole or substantial part), the work is original and all authors have read the submitted version of the manuscript and approved its submission.
CRediT authorship contribution statement
M.G. Kgatle: Investigation, Methodology, Formal analysis, Writing - original draft. B. Flett: Conceptualization, Methodology, Formal analysis, Writing - review & editing, Project administration, Supervision. M. Truter: Validation, Writing - review & editing, Visualization, Supervision. T.A.S. Aveling: Conceptualization, Formal analysis, Resources, Data curation, Writing - review & editing, Project administration, Funding acquisition, Supervision.
Declaration of competing interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Acknowledgements
1. Agricultural Research Council - Grain Crops Institute; Moses Ramusi for help with field trials.
2. Oilseed Advisory Committee for funding the project.
3. Seed companies and sunflower producers for their cooperation.
4. The National Research Foundation of South Africa (NRF).
5. The Oppenheimer Memorial Trust (Postgraduate Students) Scholarship.
6. Grain South Africa and Department of Science and Technology.
References (35)
- et al.
In vitro fungicide sensitivity of Alternaria species pathogenic to crucifers and identification of Alternaria brassicicola field isolates highly resistant to both dicarboximides and Phenylpyrroles
Crop Protect.
(2004) - et al.
Diversity and movement of indoor Alternaria alternata across the main-land USA
Fungal Genet. Biol.
(2015) - et al.
High-performance chiral separation of fourteen triazole fungicides by sulfated B-cyclodextrin-mediated capillary electrophoresis
J. Chromatogr. A
(2001) Economic Outlook Report XXIII
(2018)- et al.
The effect of seed treatments with fungicides on stem rot caused by Sclerotium rolfsii Sacc., in peanut
Pakistan J. Bot.
(2011) - et al.
Production of inoculum and field assessment of Alternaria helianthi on sunflower
Plant Dis.
(1983) - et al.
Resistance to pyraclostrobin, boscalid and multiple resistance to Pristine (to pyraclostrobin + boscalid) fungicide in Alternaria alternata causnig late blight of pistachios in California
Plant Pathol.
(2008) - et al.
Seed Treatment in Crop Health Management
(2014) - et al.
Virtual lesion of Alternaria blight on sunflower
Helia
(2005) - et al.
Three Alternaria species pathogenic to sunflower
Plant Pathol. J.
(2000)
Evaluation of fungicides for control of Alternaria leaf spot
N. Z. J. Crop Hortic. Sci.
Methods of studying population structure, including sensitivity to the fungicide silthiofam, of the cereal take-all fungus, Gaeumannomyces graminis var. tritici
Plant Pathol.
Studies on seedborne nature and management of Alternaria alternata and A. brassicae in pigeonpea
Indian J. Plant Protect.
Soybean (Glycine max L.) response to fungicides on the absence of disease pressure
Int. J. Agron.
Effect of fungicide use strategies on the control of early blight (Alternaria solani) and potato yield
Australas. Plant Pathol.
International Rules for Seed Testing
Distribution of Alternaria leaf blight of sunflowers caused by Alternaria alternata in South Africa. Accepted with minor corrections in
J. Agric. Rural Dev. Tropics Subtropics
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