The objective of this work was to evaluate the efficacy of cotton seed treatment with fungicides in the control of R. solani seedling damping-off. This experiment was carried out under greenhouse conditions at Embrapa Agropecuária Oeste, in Dourados city, Mato Grosso do Sul State, Brazil. Treated and untreated seeds of the cultivar DeltaOpal were sowed in sand contained in plastic trays, placed in individual and equidistant wells, 3cm deep. Into each plastic tray were put 5g of the pathogen inoculum. The inoculation of R. solani AG-4 was done by the homogeneous distribution of the fungus inoculum onto the substrate. The fungus was grown for 35 days on autoclaved oat seeds and then ground to powder using a mill (1mm). The evaluations were done based on symptoms development and seedling survival. The significant effect of the fungicide treatment on initial and final seedling emergence, as well as in the control of pre and post-emergence damping-off was observed. The best results were obtained with tolylfluanid+pencycuron+triadimenol and azoxystrobin+fludioxonil+mefenoxan, followed by carboxin+thiram, PCNB and pencycuron. The least efficient fungicide was carbendazim+thiram. Seed treatment with fungicide combinations provided better results than the use of the single ones. No significant effect was observed in relation to speed of emergence index, seedling height and seedling fresh weight.
seedling emergence; inoculation; fungus
