新疆大蒜叶疫病的研究——Ⅱ病菌越冬致病性病害流行因素及防治

THE GARLIC LEAF BLIGHT IN XINJIANG I . OVERWINTERING, PATHOGENICITY OF PATHOGEN,OCURRENCE FACTORS AND DISEASE CONTROL

试验结果表明,本菌(Stemphylium vesicarium (Wallr.) Simons)以病残体上分生孢子和菌丝体在田间和冷藏室越冬,9月至翌年6月检查,分生孢子萌发率为16.4～41.3％。人工接种试验指出,不论有无伤口,病菌均可侵染大蒜,但洋葱与大葱在伤口接种条件下病情较重。在自然条件下,大蒜的斑点型病状出现于6月下旬,7月为病情高峰期。影响病情的天气因素,主要是7月份温度和7月中旬的降水量(r=0.69)。如果7月雨次多、雨时长,病情即极为严重,可导致蒜田绝收。化学防治试验结果,以腐霉利防效最佳。从7月上旬开始,每间隔10～13天喷药1次。喷药2～3次即可取得较好的防治效果。

The results of experiments showed that the pathogen (Stemphylium vesicarium (Wallr. ) Simmous) overwinters mainly in remains of the host by the form conidia and mycelia in the field or coolstorage. The germination percentage of the overwintered conidia (keeped from September to next June) still remains 16. 4~41. 3% under experimental conditions. The pathogen can also infect common onion and fistular onion through intact leaf surface or wounds when inoculation has been made. But wound infection causes more severe than that by direct infect. Incubation period is two or three days at 28℃- 30℃.leaf spots occur in middle to late June and the peak of incidence reaches in July. The main factor which influence the degree of disease occurence hinge on the rainfall, especially the frequency and rainy period in July (r = 0. 69). In the worst circumstance the whole yield of the garlic growing may be abandoned as a result of the disease. On the contrary ,the damage will be weakened correspondingly with the delay of rainy preiod. Among the 11 fungicides tested, Procymidone is the best one. The ideal control effec-tivity can be achieved readily, if twice sprayings could be made from the early July at intervals of 10-13 days.