Methods for Detection ofAlternaria padwickiiin Rice Seeds

Abstract

AbstractThe fungusAlternaria padwickiihas been frequently detected in seed tests of rice collected from commercial crops in Corrientes Province, Argentina. This pathogen causes germination inhibition, seedling death or spotted grains and is the causal agent ofAlternarialeaf spot. The pathogen survives as mycelia and sclerotia on seeds, plant debris and soil. Four detection methods were compared in laboratory tests, to select the best for a quick identification of the fungus in seeds. The methods were (i) Blotter Test (ii) Potato glucose agar, (iii) Bean agar (BA) and (iv) Malt extract agar. Twenty seed samples of different varieties of rice collected from Empedrado, Goya, Itá Ibaté, La Cruz, Mercedes, Paso de los Libres and Perugorría localities (Corrientes, Argentina), were analyzed in the assays. Theanovatest and the Tukey multiple range test were applied on the data to compare theA. padwickiiincidence among the varieties and detection methods. BA method was found more sensitive than other methods forA. padwickii. The incidence values ranged from 3.6 to 76%. The statistical analysis demonstrated that the BA method was the most efficient for the detection of seed pathogens, and it could be useful in studies of transmission and chemical control.