Verticillium dahliae is a soilborne pathogen that causes wilt in many economically important crops. It produces melanized microsclerotia for its long-term survival in soil. Accurate quantification of viable microsclerotia in soil prior to planting is essential for predicting the risk of wilt. Melanin is believed to help microsclerotia resist to or tolerate abiotic stresses. We studied the temporal dynamics of both melanized and melanin-deficient microsclerotia of V. dahliae in four types of soils with or without addition of two biocontrol products (one based on Trichoderma viride; and the other based on two Bacillus strains: B. subtilis and B. amyloliquefaciens). Of the four soil types, two were from wheat and maize (non-host to V. dahliae) fields and the other two from sites with history of continuous cropping of cotton and pepper (both susceptible to V. dahliae). Results showed that the survival of microsclerotia in soils over time can be satisfactorily described by a negative exponential decline model. Microsclerotium mortality was much greater in the soils from wheat and maize field than from cotton and pepper, irrespective of biocontrol agents. Similarly, mortality of melanin-deficient microsclerotia was much greater than melanized microsclerotia. Both biocontrol products resulted in additional mortality of microsclerotia, especially Bacillus spp. There were significant interactions between soil origin, microsclerotium type and biocontrol treatment in affecting microsclerotium mortality. These results demonstrated that melanin contributes to the long-time survival of microsclerotia in soil and suggested that combination of biocontrol with rotation with non-host crops can be effective in reducing the number of viable microsclerotia of V. dahliae in soil.

黄萎病菌是一种土壤传播的病原体，可在许多重要的经济作物中引起枯萎。它可产生黑色素化菌核，以在土壤中长期存活。播种前准确定量土壤中的活菌核是预测枯萎风险的关键。黑色素被认为可帮助微核菌抵抗或耐受非生物胁迫。我们研究了两者的时空动态变暗和黑色素缺失的微菌核黄萎病四种类型的土壤中添加或不添加基于两个生物防治产品（一个绿色木霉;另基于两个芽孢杆菌菌株：枯草芽孢杆菌和淀粉芽孢杆菌）。四大土壤类型，两人从小麦和玉米（非主机黄萎病）领域，从棉花和辣椒的连作的历史遗址的另外两个（都容易黄萎病）。结果表明，通过负指数下降模型可以令人满意地描述土壤中小菌核的存活时间。不论使用何种生物防治剂，小麦和玉米田土壤中的小菌核死亡率都比棉花和胡椒高。同样，缺乏黑色素的菌核的死亡率比黑色素化的菌核的死亡率高得多。两种生物防治产品均导致微菌核特别是芽孢杆菌的额外死亡spp。土壤来源，微菌落类型和生物防治之间存在显着的相互作用，从而影响微菌落的死亡率。这些结果表明，黑色素有助于土壤中微核菌的长期存活，并表明生物防治与轮作与非寄主农作物的组合可以有效减少土壤中大麦弧菌的存活数。