Controlling fungal diseases of vegetables with biocides

Abstract

Plant diseases continue to play a major limiting role in agricultural production, particularly in intensively managed crops. Fungal diseases of vegetables are one of the economic problems and cause greater losses of yield. Pre- and postharvest chemical treatments traditionally have been used against plant pathogenic fungi. Concerns about food safety, environmental quality and pesticide resistance have dictated the need for alternative pest management techniques. There is renewed interest in the development of alternative means of controlling fungal development in the field and after harvest. There are a limited number of published reports on the effects of biocides on control of fungal diseases. Some detergents have been found to be highly antifungal against some plant pathogenic fungi, such as powdery mildew (Sphaerotheca fuliginea) on cucumber. Recently, the efficacy of nonionic surfactants in the control of root rot on cucumber and pepper was reported. Selected organic and inorganic salts are active antimicrobial agents and their antifungal activity has been demonstrated on several plant-pathogens systems. Potassium bicarbonate has been shown to control both growth and development of soil-borne pathogen Sclerotinia sclerotiorum. Bicarbonates were used in controlling powdery mildew (Leveillula taurica) on pepper. Potassium or sodium bicarbonate salts controlled infection by powdery mildew (Sphaerotheca fuliginea) on squash. Inorganic fertilizer salts were found to reduce powdery mildew (Erysiphe orontii) on tomato. Bicarbonate salts provided control of gummy stem blight (Didymella bryoniae) and Alternaria leaf blight (Alternaria cucumerina) on muskmelon. Potassium or sodium bicarbonate was tested to study their effect on early blight disease (Alternaria solani) of potato. Postharvest application of salts reduced the severity silver scurf (Helminthosporium solani) and dry rot (Fusarium spp.) on potato, cavity spot (Pythium sulcatum) and black root rot (Chalara elegans) on carrots. This paper reviews the literature of fungal disease suppression by applications of biocides as alternatives to fungicides.