ABSTRACT

A greenhouse study was conducted to examine the impact of populations of Rotylenchulus reniformis and seedling disease fungi on early season disease and cotton development. Treatments consisted of Fusarium chlamydosporum, F. equiseti, F. lateritium, F. moniliforme, F. oxysporum, F. oxysporum f.sp. vasinfectum, F. proliferatum, F. semitectum, F. solani, F. sporotrichioides, Rhizoctonia solani, Thielaviopsis basicola. Pots containing 500 g of soil were infested with an inoculum concentration of 1% (w/w) of fungal treatments alone and in combination with 2000 R. reniformis juvenile and vermiform adult nematodes in a factorial arrangement. There was no significant interaction between R. reniformis and seedling disease fungi for survival, height, disease severity, and shoot dry weight. Seedling survival counts were lower at 42 days after plant-ing for every treatment except F. chlamydosporum and F. semitectum. Treatments containing R. solani, T. basicola, F. oxysporum f.sp. vasinfectum, and F. moniliforme displayed significantly shorter plants at 14, 28, and 42 days after planting. Disease severity observed at 42 days after planting was greater for R. solani compared to any other treatment. Treatments infested with R. solani, T. basicola, F. oxysporum f.sp. vasinfectum, F. moniliforme and F. lateritium resulted in significantly less shoot weight. Cotton seedlings from the non-infested soil treatments yielded higher shoot dry weight than seedlings from R. reniformis infested soil. Data recorded for root dry weights determined an interaction between fungal treatments and the presence of R. reniformis. The control and F. semitectum without R. reniformis, displayed significantly greater root dry weights than the control and F. semitectum with R. reniformis. Populations of R. reniformis recorded at 42 days after planting were significantly lower in the presence of seedling disease fungi especially R. solani, T. basicola, F. oxysporum, F. oxysporum f.sp. vasinfectum, and F. moniliforme.