苜蓿菌核病生防菌及化学药剂的筛选

通过毒力测定法比较11种化学药剂对苜蓿菌核病的抑菌效果,其中45%五氯·福、50%速克灵和55%甲硫·菌核净可湿性粉剂3000倍液均能抑制病原菌生长。温室生测表明45%五氯·福防治苜蓿菌核病效果最好,500倍液防效达73.9%。从江苏省句容地区苜蓿根围土壤中分离到415株细菌,采用平皿对峙法从中筛选到3株对菌核病具有拮抗效果的生防菌,代号S1和S2的菌株抑菌效果最好,抑菌带超过1.5cm。温室生测菌株S2对苜蓿菌核病的生防效果最好,接种病原菌10d后防效达67.5%,15d后为61.7%。

Screening of Microbes and Fungicides for Controlling Alfalfa Sclerotinia Stem Rot

Sclerotinia trifoliorum NJ1 is the pathogene causing sclerotinia stem rot of alfalfa. The toxicity of 11 fungicides against NJ1 were measured to determine their efficiency in inhibiting the growth of mycelium. Thiophanate-methyl+dimetachlone, sumelix or quintozene-thiram, when diluted 3 000 times, could completely restrain the germination of S.trifoliorum NJ1 on a PDA plate. Furthermore, it was shown that quintozene-thiram (500×), the most effective agent, had an efficiency of 73.9% in controlling alfalfa sclerotinia stem rot. Three bacterial agents, screened from 415 strains isolated from alfalfa sclerotinia stem rot rhizosphere soil in Jurong, Jiangsu Province, were found to be able to inhibit NJ1 in the dual-culture test on PDA plates. Among them strains S1 and S2 were the strongest antagonists with suppressive bands exceeding 1.5 cm. In the greenhouse, strain S2 was the best agent to control alfalfa sclerotinia stem rot, the efficiency (10 d) and 15 d after pathogene inoculation reached 67.5% and 61.7%, respectively.