TREATMENT OF YAM TUBERS INFECTED BY SCUTELLONEMA BRADYS WITH SODIUM HYPOCHLORITE

Abstract

Dry rot caused by Scutellonema bradys, Pratylenchus coffeae, and P. brachyurus is considered the most important disease of yam (Dioscorea spp.) in Brazil. The aim of this work was to evaluate the effect of sodium hypochlorite on suppression of S. bradys in yam tubers. Greenhouse experiments were performed twice in a completely randomized factorial design. Sodium hypochlorite treatments applied at concentrations of 0, 0.5, and 1.0% with immersion periods of 20, 40, and 60 min were evaluated; all treatment combinations were replicated eight times. Three months after planting, percent emergence of shoots from the seed tubers was evaluated. Scutellonema bradys population density in soil, roots and tuber peels, the total nematode population, and the reproduction factor, were evaluated 6 months after planting. In both assays, shoot emergence did not differ among concentrations of sodium hypochlorite and immersion periods. However, S. bradys populations were reduced as the sodium hypochlorite concentration increased when compared to the control. The most conservative treatment, sodium hypochlorite at 1.0% for an immersion period of 20 min, could be useful for disinfection of yam tubers infected with S. bradys.