天水地区小麦白粉病发生发展规律

The Laws of Occurence and Development of Powdery Mildew of Wheat in Tianshui Area

通过4年调查和试验研究表明,天水地区夏秋期间,自生小麦苗上的白粉病发生普遍。有性世代闭囊壳,在本地不能活到冬麦出苗后直接侵染秋苗,但可在夏季存活期内侵染自生麦苗。这里距春麦区很近,春麦上的分生孢子有可能传来侵染自生麦苗。因此自生麦苗上的分生孢子,是冬麦秋苗的初侵染来源。冬麦早播病重晚播病轻,在海拔1590m的地方,10月7日播种,秋苗不发病。病菌以菌丝在麦苗中越冬,4月初先在阳坡地开始发展;4月是始发期,此后至5月中旬是普发期,5月下旬开始进入盛发期。并提出了病害流行的条件。

Investigations and experiments in 4 years show> d that the occurence of powdery mildew on voluntary seedlings of wheat was common in Tianshui area in Gansu Province. Cleistothecia can not survive to emergence of winter wheat so it was not direct sources of infection to the autumn seedlings of wheat in the area, but ascospores can infeet voluntary seedlings of wheat in the summer. Here is v. ry near the spring wheat growing area, and conidia on spring wheat there may spread to voluntary seedlings of wheat. Therefore, conidia on voluntary seedlings of wheat are the primary sources to infect autumn seedlings early sowing wheat. There are no diseases to be found n the autumn seedlings of wheat sown on Oct.7 in the regions w.'th an altitude of 1590 rn above sea level. The fungus overwintering in the leaf with hypha showed first the disease at the beginning of April at south of a hill then spread to flat plain. The beginning period of the disease was usually in April, and the disease oc-cured generally before the second decade of May, then it occured reatly in the third decade of May. Epidemical conditions of the disease were given in the paper.