ABSTRACT

Control of economically important gramineous weeds has been overly dependent on chemical herbicides resulting in herbicide resistance and pollution. The development of a biocontrol technique may be an optional approach to weed control. Bipolaris panici-miliacei strain SX5-2 was isolated from diseased Microstegium vimineum plants. Pathogenicity, host range test, culture and mass production, crop sensitivity, formulation development and field trials were conducted to evaluate the potential of this strain for a bioherbicide. Pathogenicity tests showed percent incidence was up to 90% at a conidial suspension concentration of 10⁵ conidia/mL on M. vimineum under greenhouse conditions and more than 80% in the field. Host range tests on 57 species in 17 families determined that B. panici-miliacei strain SX5-2 was safe for rice, wheat, sorghum, soybean, cotton, vegetables, Zoysia japonica turf and most dicotyledonous plants. Only maize and sugar cane were severely infected. Pathogenicity bioassays showed that the strain could control those seven tested gramineous weeds Digitaria sanguinalis, Panicum virgatum, Echinochloa crus-galli, Microstegium japonicum, Microstegium nodosum, Sorghum sudanense and Leptochloa chinensis in the main dryland and paddy fields. Culture and mass-production studies revealed that combined submerged and solid fermentation with bran and sawdust was feasible for mass production of conidia. Therefore, based on virulent pathogenicity and feasible mass production, B. panici-miliacei may have a promising potential to be developed into a bioherbicide for biocontrol of grass weeds in most crops but not in susceptible maize or sugarcane.

摘要

经济上重要的禾本科杂草的控制过度依赖化学除草剂，导致除草剂抗性和污染。生物防治技术的发展可能是杂草防治的一种可选方法。从患病的Microstegium v​​imineum植物中分离出Bipolaris panici-miliacei菌株 SX5-2 。进行了致病性、宿主范围测试、培养和大规模生产、作物敏感性、配方开发和田间试验，以评估该菌株作为生物除草剂的潜力。^{致病性测试表明，在分生孢子悬浮液浓度为 10 5}分生孢子/mL 时，M. vimineum的发病率百分比高达 90%在温室条件下，80%以上在田间。对 17 个科 57 个物种的宿主范围测试确定B. panici-miliacei SX5-2菌株对水稻、小麦、高粱、大豆、棉花、蔬菜、结缕草草皮和大多数双子叶植物是安全的。只有玉米和甘蔗受到严重感染。致病性生物测定表明，该菌株可以控制这7种被测禾本科杂草红木犀、紫穗稷、稗草、日本小刺参、结节小刺参、苏丹高粱和千金子。在主要的旱地和稻田。培养和大规模生产研究表明，与麸皮和锯末相结合的深层和固体发酵对于分生孢子的大规模生产是可行的。因此，基于剧毒致病性和可行的大规模生产，B. panici-miliacei可能具有发展成为生物除草剂的潜力，用于生物防治大多数作物中的禾本科杂草，但不适用于易感玉米或甘蔗。