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

Abstract

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.

Verticillium wilt of olive: a case study to implement an integrated strategy to control a soil-borne pathogen

“…However, the individual effect of these parameters on the pathogen and the disease could be masked by the interaction with factors such as soil texture, rate of organic matter mineralization, soil microbiota activity, etc. (Gamliel et al 2000;Lazarovits et al 2000;Goicoechea 2009). …”

“…Indeed, from the variety of molecular markers identified, proper selection can be made from those ones clearly associated with specific groups or linked to a particular phenotypic trait (i.e., pathotype). Thus, specific DNA sequences can be identified to design VCG-specific or pathotype-specific primers to be used in PCR-based detection and diagnosis procedures of V. dahliae isolates infecting olive or any other host (Pérez-Artés et al 2000;Mercado-Blanco et al 2003b;Collado-Romero et al 2006, 2009 (Fig. 4).…”

“…However, the effect of factors such as pH changes in soil upon the application of (in)organic amendments to control Verticillium wilt diseases in several herbaceous hosts has been studied to some extend (Lazarovits et al 2000;Pegg and Brady 2002;Goicoechea 2009). Verticillium dahliae normally occurs in neutral to alkaline soils (pH 6-9), since acidic pH's (below 5.5) are inhibitory to pathogen growth and MS production and survival.…”

“…Soil texture seems to have a variable effect both on the pathogen and on the disease in several hosts, a likely consequence of the aforementioned complex interactions taking place between soil itself and diverse factors such as organic matter abundance, pH, temperature, moisture, availability of nutrients and/or presence and diversity of fungistatic soil microflora (Pegg and Brady 2002;Goicoechea 2009). Our investigations have also explored whether VWO incidence could be correlated with the soil type where olive orchards are established ).…”

“…Soil solarization is one of the most effective physical control methods to reduce inoculum density of soilborne pathogens such as V. dahliae (Katan 1987;Katan 2000a;Goicoechea 2009). Soil covering with transparent polyethylene films, combined with abundant watering, makes it possible to heat soil by sun irradiation to temperatures lethal for many soil-borne pathogens and weed seeds.…”