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作者研究了近几年来导致黑龙江省南瓜大面积烂秧烂瓜的病原菌的形态、生理及致病性。该病原菌在ＣＡ上菌落呈非绒毛状，边缘清晰。菌丝柔韧，平均宽５．５０μｍ。ＣＡ培养基上和水中均不产生厚壁孢子。孢囊梗单轴分枝或不规则分枝。诱发形成椭圆形、近球形、卵形或不规则形孢子囊。孢子囊乳突明显，呈半球形，多数１个，少数２个，平均高度４．８０μｍ。孢子囊平均长５７μｍ，宽３９μｍ，长宽比为１．５。孢子囊脱落后具长柄，平均柄长４５μｍ，偶尔侧面着生。孢子囊萌发一般产生游动孢子，排孢孔平均宽７．１０μｍ，有时也产生静孢子球。异宗配合，藏卵器球形，平均直径３２μｍ，雄器围生，高１５．６０μｍ，宽１３．６０μｍ。菌丝生长最适温度２２℃～３２℃，最高生长温度３７℃。能利用淀粉作为唯一碳源，淀粉水解指数７４％。在含有１ｍｇ·ｋｇ－１孔雀石绿的培养基上能正常生长。能侵染多种葫芦科植物和辣椒、豌豆等植物，致病力较强，寄主范围较广。接种马铃薯块茎和苹果果实只造成轻微腐烂。根据Ｈｏ（１９８１）和Ｎｅｗｈｏｏｋ（１９７８）的检索表，将该病原菌鉴定为辣椒疫霉Ｐｈｙｔｏｐｈｔｈｏｒａｃａｐｓｉｃｉ。
The author has studied the morphology, physiology and pathogenicity of the pathogenic bacteria causing large-scale rotten seedlings of pumpkin in Heilongjiang Province in recent years. The pathogen colonies on CA are non-villous with sharp edges. Mycelium flexible, the average width of 5.50μm. Thick-walled spores were not produced on CA medium and in water. Saplings uniaxial or irregular branches. Induced the formation of oval, nearly spherical, oval or irregularly shaped sporangia. Sporangia mastoid obvious, hemispherical, most 1, a few 2, the average height of 4.80μm. Sporangia average length 57μm, width 39μm, aspect ratio of 1.5. Sporangia with long stems off, the average handle length 45μm, occasionally side with students. Sporangia germination generally produce zoospores, rows of spores average 7.10μm wide, and sometimes produce sporozoites. Heterophile, ovipositor spherical, average diameter 32μm, perinatal, height 15.60μm, width 13.60μm. Mycelial growth optimum temperature of 22 ℃ ~ 32 ℃, the maximum growth temperature of 37 ℃. Can use starch as the only carbon source, starch hydrolysis index 74%. Normal growth on medium containing 1 mg · kg -1 malachite green. Can infect a variety of Cucurbitaceae plants and peppers, peas and other plants, stronger virulence, host a wider range. Inoculation of potato tubers and apple fruits causes only slight decay. According to the search table of Ho (1981) and Newhook (1978), the pathogen was identified as Phytophthora capsici.