Impact of stale seedbed production on seedling diseases in cotton

Cotton production using conservation tillage practices has increased in the past decade. Most studies involving reduced tillage have shown a reduction in plant populations, which has been attributed to seedling diseases. Although most of these studies have focused on no-till production, cotton planted in the mid-south is often planted using stale seedbeds. The objective of this research was to compare the effect of stale seedbed production and conventional tillage with and without in-furrow fungicides on the incidence and severity of seedling diseases. Tillage systems were established in the fall to focus on the effect of tillage on inoculum density and distribution and to minimize differences in the soil environment between tillage treatments. From 1998 to 2001, cotton was planted and seedling disease was evaluated by counting surviving plant populations, estimating stand uniformity, and conducting root and hypocotyl disease indices. Soil populations of Pythium spp. and Rhizoctonia spp. were also estimated. Plant populations were significantly different between tillage treatments in 1998 and between in-furrow treatments in 2000. Skip variables were not different in any year. Soil populations of Rhizoctonia spp. were highly variable and not significantly different among treatments in any year. Populations of Pythium spp. were higher in stale seedbed plots in 2000 and 2001. There were no differences in seed cotton yield in any year. In this study, stale seedbed production increased the incidence and severity of seedling diseases of cotton in only one of four years, but the disease was effectively managed with the application of in-furrow fungicides. These results indicate that the potential for an increase in seedling diseases associated with stale seedbed production is minimal and is not sufficient to overlook the potential benefits of this tillage system.