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本文对小麦根围土壤中的腐霉Ｐｙｔｈｉｕｍ种类、种群数量消长及其致病性作了初步研究。作者从不同生育期的小麦根围和内根围共分离出２０３个腐霉菌株，除６９个菌株缺乏产生有性器官而未能鉴定外，其余１３４个菌株分别属１０个腐霉种，其中粘腐霉Ｐ．ａｄｈａｅｒｅｎｓ、链状腐霉Ｐ．ｃａｔｅｎｕｌａｔｕｍ和绚丽腐霉Ｐ．ｐｕｌｃｈｒｕｍ为浙江省分布新记录。Ｐ．ｓｐｉｎｏｓｕｍ是优势腐霉种类，在小麦根围和内根围出现率分别为２７．４３％和３５．７１％，Ｐ．ｕｌｔｉｍｕｍ和Ｐ．ｉｒｅｇｕｌａｒｅ也较为常见，而Ｐ．ａｐｈａｎｉｄｅｒｍａｔｕｍ却极少出现。在小麦苗期和分蘖期腐霉数量较丰富，生育中后期较贫乏，这一消长变化可能主要与小麦生育期和土壤温度有关。致病性试验结果表明：Ｐ．ｉｒｅｇｕｌａｒｅ和Ｐ．ｓｐｉｎｏｓｕｍ分别对小麦和水稻有较强的致病作用；Ｐ．ａｐｈａｎｉｄｅｒ－ｍａｔｕｍ、Ｐ．ｉｒｒｅｇｕｌａｒｅ和Ｐ．ｓｐｉｎｏｓｕｍ则对茄子、辣椒和番茄的致病力较强。Ｐ．ｓｐｉｎｏｓｕｍ、Ｐ．ｕｌｔｉｍｕｍ和Ｐ．ｉｒｅｇｕｌａｒｅ的种内菌株间致病性差异不明显。
In this paper, Pythium species, population growth and pathogenicity were studied in soil rhizosphere of wheat. A total of 203 Pythium strains were isolated from wheat root and endochronal glands at different growth stages. Except 69 strains lacking sexual organs and failed to identify, the other 134 strains were 10 Pythium species, of which sticky Pythium P. adhaerens, Pythium pectin. catenulatum and Pythium pv. Pulchrum is a new record for Zhejiang Province. P. Spinosum is the dominant species of Pythium, with the incidence rates of 27.43% and 35.71% in the root circumference and the root end of wheat, respectively. ultimum and P. iregulare is also more common, while P. Aphanidermatum is rare. The number of Pythium in wheat seedling and tillering stage is richer, and the late growth stage is poorer. The change of growth and decline may be mainly related to wheat growth period and soil temperature. Pathogenicity test results show that: P. iregulare and P. Spinosum has strong pathogenicity to wheat and rice respectively; aphanider-matum, P. irregulare and P. Spinosum is more virulent to eggplant, peppers and tomatoes. P. spinosum, P. ultimum and P. There was no significant difference in the pathogenicity among the isolates of iregulare.