Managing Seedling Disease Problems on Rice Through Fungicides, Adapted Cultivars, and Cropping Systems

Stand problems consistently cause significant production and management losses in Arkansas rice fields. In 2002, many fields in Arkansas had severe stand losses. Three control practices are being examined in this project for managing stand losses due to seedling diseases: 1) seed treatment fungicides, 2) development of cold-tolerant cultivars, and 3) the use of disease-suppressive production systems. The three types of fields from which seedlings were taken in 2002 were: a) fields at the Rice Research and Extension Center (RREC) at Stuttgart where cold-tolerant and standard genotypes of rice were planted over a range of soil environments; b) fields from several rice-producing counties in Arkansas with the stand-establishment problems; and c) fields at the RREC where there is a continuing study of the impact of various cultural practices– crop rotation and tillage–on rice yields. From the pathogenicity studies outlined, results suggest that isolates of Pythium spp. from fields having poor stand establishment in 2002 were more virulent than isolates from randomly selected plants from field studies, supporting the diagnosis that Pythium seed and root rot, caused by Pythium spp., was the cause of these stand failures. These Pythium isolates will be used to determine if the cold-tolerant rice genotypes have increased resistance to Pythium damping-off at lower planting temperatures compared to standard cultivars.