To what extent are soil amendments useful to control Verticillium wilt?

The genus Verticillium includes several species that attack economically important crops throughout the world. The control of Verticillium spp. becomes especially difficult when they form microsclerotia that can survive in the field soil for several years. It has been common practice to fumigate soil with chemicals such as methyl bromide and/or chloropicrin to control soil-borne fungal pathogens. Other chemicals that are used against Verticillium spp. are the antifungal antibiotic aureofungin, the fungicides benomyl, captan, carbendazim, thiram, azoxystrobin and trifloxystrobin and the plant defence activator acibenzolar-S-methyl. However, the potential risks involved in applying phytochemicals to crop plants for both the environment and human health, together with their limited efficacy for controlling Verticillium-induced diseases, support the need to find alternatives to replace their use or improve their efficacy. Soil amendment with animal or plant organic debris is a cultural practice that has long been used to control Verticillium spp. However, today the organic farming industry is becoming a significant player in the global agricultural production scene. In this review, some of the main results concerning the efficacy of several soil amendments as plant protectors against Verticillium spp. are covered, and the limitations and future perspectives of such products are discussed in terms of the control of plant diseases.