北方植棉区棉花黄萎病菌生理分化类型研究

Physiological Differentiation of Verticillium dahliae on Cotton in Northern China

通过对采自北方植棉区落叶和非落叶病株的５１个棉花黄萎病菌系致病力分化测定结果，确定我国北方植棉区存在落叶类强致病力菌系；混合类中度致病力菌系及非落叶类弱致病力菌系的３个致病类型，并分别占测试菌的４１．５１％、３５．８５％和２２．６４％，其中９个强致病菌系致害棉苗出现落叶程度与对照菌的落叶程度相当或略重，表明河北、山东、河南植棉区重病田有落叶型黄萎菌系。病菌培养性状研究，得出３个培养型，即黑色菌落型、灰白色菌落型与白色菌落型。明确了黄萎病菌生长最佳温度为２５℃，这一结果同田间黄萎病大发生要求的温度一致。

Three pathogenic styles of V.dahliae on cotton, severs defoliating strains, intermediate strains and nondefoliating weak strains, were confermed in northern area of China. The percentage of them in all the determined isolates was 41.51%, 35.85%, 22.64% respectively. Defoliating degree made by 9 severe strains was similar with or more serious than that made by control defoliating strains. The result indicated that defoliating strains of V.dahliae had been in Hebei, Shandong, Henan provinces and caused serious cotton disease. Three cultural styles, black colonial style, grey white colonial style and white colonial style, have been found by studying the cultural characteristics of V.dahliae. The optimum growth temprature of V.dahliae is 25℃, which in accordance with that cotton Verticillium wilt happened in field.