Observations and research results over the last five to 10 years indicate that seed treatments now available for treating seed may give adequate control of cotton seedling diseases in some fields without the use of a supplemental soil fungicide treatment. An experiment was initiated at the University of Tennessee West Tennessee Agricultural Experiment Station at Jackson in 1992 and continued in 1993 to evaluate the comparative effectiveness of seed treatment and seed treatment plus soil application of fungicides for control of seedling diseases. 'Deltapine 41' was planted April 24, 1992; 'Deltapine 50' was planted April 29, 1993, on a Vicksburg silt loam soil. The plot area was planted to soybeans in 1991. Plots were planted with seed treated with Vitavax-PCNB, 6 fl oz/cwt + Apron FL, 0.75 fl oz, and Vitavax-PCNB, 6 fl oz + Anchor FL, 0.75 fl oz, in 1992 and Vitavax-PCNB + Apron FL (rates above) and GUS FR19, 3 fl oz + Anchor FL, 0.75 fl oz, in 1993. Other plots were planted with seed treated with Vitavax-PCNB + Apron and received supplemental fungicide soil treatments applied as in-furrow granules (Ridomil PC 11G, 10 lb./acre, 1992; Ridomil PC 11G and Terraclor Super X 12.5G, both at 8 lb., in 1993) or hopper-box dust (Prevail, 8 oz/cwt). One supplemental treatment in 1992 included Prevail (8 oz) + Ridomil PC (7 lb.). Control plots received untreated seed and no soil treatment. Five replicates of each treatment were planted in a randomized complete block design with a two-row planter equipped for application of the soil fungicides.

Stand counts in all treated plots in 1992 were significantly higher (about two-fold) than in untreated control plots. Counts in plots receiving seed treatment alone were equal to those receiving both treatments. Skip levels, measured and counted in each plot, were significantly lower in treated plots than in untreated plots following seed treatment alone or use of both treatments. Plant vigor was greatly increased by all treatments over the untreated control. Vigor in plots receiving seed treatment only was not significantly different from vigor in plots receiving both treatments.

Yields were significantly improved by seed treatment alone and by seed treatment plus Ridomil granules applied in-furrow. Yields were not increased in plots receiving seed treatment plus Prevail hopper-box or Ridomil granules in-furrow at a reduced rate plus Prevail hopper-box.

Incidence and severity of seedling diseases was high in the plot area in 1993. Seed treatments, both with and without supplemental soil treatments, significantly increased stand counts (two- to four-fold) over the control. Plots planted with seed treated with Vitavax-PCNB plus Apron had significantly higher stands than plots receiving seed treatment plus Terraclor Super X granular or Prevail hopper-box treatments. All fungicide treatments significantly reduced skip levels. Vitavax-PCNB plus Apron seed treatment again had significantly lower skip levels than Terraclor Super X or Prevail treatments plus seed treatment. Seed treatments and seed treatment plus soil treatment significantly improved plant vigor over the control treatment but were not significantly different from each other. Yields were significantly increased by all fungicide treatments except seed treatment plus Prevail hopper-box.

These results confirm earlier observations and research findings that in some fields seed treatments of fungicides can give adequate cotton seedling disease control without the use of an additional fungicide treatment. A grower who knows the disease history of his fields could possibly save money on fungicide treatment in some fields.