MANAGEMENT OF POWDERY MILDEW IN GREENHOUSE TOMATO PRODUCTION WITH BIORATIONAL PRODUCTS AND FUNGICIDES

Abstract

Powdery mildew (Oidium sp.) is an important disease of greenhouse-produced tomatoes. The severity of the disease, the widespread distribution of the pathogen, and its ability to develop insensitivity to fungicides with a narrow mode of action requires the identification of viable alternatives to conventional fungicides. Various products are available or in development that have the potential to contribute to the management of powdery mildew of tomato. Biorational products and fungicides including Cease and Serenade ASO (Bacillus subtilis QST 713 strain), Actinovate (Streptomyces lydicus), JMS stylet oil (paraffinic oil), Kocide 3000 (copper hydroxide), Microthiol Disperss (sulfur), Milstop (potassium bicarbonate), OxiDate (hydrogen dioxide), Rally 40WSP (myclobutanil), Regalia (extract of Reynoutria sachalinensis), Nufarm-Cuproxat concentrate (copper sulfate), cedar oil, citronella, clove oil, cottonseed oil, lemongrass, Ortho-Eco sense 3-in-1 Rose and Flower Care (sulfur and pyrethrin), Ortho-Eco sense Garden Disease Control (copper octanoate), whole milk, Prestop (Gliocladium catenulatum J1446), and Quintec (quinoxyfen) were tested. The experiments were done twice, each with four replicates per treatment. The severity of powdery mildew on foliage and phytotoxicity were evaluated using a scale of 0-100% foliage affected. In both experiments the severity of powdery mildew was moderate (~20% foliage affected). Cottonseed oil, Rally 40WSP, whole milk and Microthiol Disperss provided >87% control of powdery mildew compared to the non-treated control in both experiments, with little or no phytotoxicity. Cedar oil, lemongrass, Regalia, citronella, both Ortho-Eco sense products, clove oil, Milstop, JMS stylet oil, and Quintec reduced the severity of powdery mildew at least 39% in the first experiment and 62% in the second experiment. Many of the products were slightly phytotoxic on tomato foliage, but JMS stylet oil, cedar oil and citronella damaged foliage significantly compared to the non-treated control in both experiments.