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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。
Based on the results of pathogenicity determination of 51 cotton Verticillium dahliae strains collected from deciduous and non-defoliated plants in northern cotton-growing areas, it was confirmed that there were strong virulent deciduous strains in cotton-growing areas in northern China. Pathogenic bacteria and non-deciduous weak pathogenic strains of the three pathogenic types, and accounted for 41.51%, 35.85% and 22.64% of the tested bacteria, of which 9 strong pathogenic bacteria The degree of deciduous leaves that caused the damage of cotton seedlings was quite or slightly heavier than that of the control ones, indicating that there was a deciduous type of Verticillium dahliae in the seriously ill plants in the cotton planting areas of Hebei, Shandong and Henan. Bacterial culture traits, resulting in three culture-type, that is, black colonies, gray-white colonies and white colonies. The optimum temperature for the growth of Verticillium dahliae was 25 ° C, which is consistent with the temperature required for the occurrence of Verticillium wilt in the field.