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Disease Control and Pest Management

New Systemic Fungicides for the Control of Cotton Seedling Disease. G. C. Papavizas, Soilborne Diseases Laboratory, Plant Protection Institute, Agricultural Research, Science and Education Administration, U.S. Department of Agriculture, Beltsville, MD 20705; J. A. Lewis(2), E. B. Minton(3), and N. R. O’Neill(4). (2)Soilborne Diseases Laboratory, Plant Protection Institute, Beltsville, MD 20705; (3)Cotton Research Laboratory, Lubbock, TX 79401; (4)Field Crops Laboratory, Plant Genetics and Germplasm Institute, Beltsville, MD; (2)(3)(4) Agricultural Research, Science and Education Administration, U.S. Department of Agriculture. Phytopathology 70:113-118. Accepted for publication 13 August 1979. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1980. DOI: 10.1094/Phyto-70-113.

The new systemic fungicide N-cyclohexyl-N-methoxy-2,5-dimethyl-3-furancarboxamide (BAS 389) was combined in acetone with one of the two other new systemic fungicides N-(2,6-dimethylphenyl)- N-(methoxyacetyl) alanine methylester (CGA-48988) and propyl [3-(dimethylamino)propyl] carbamate HCl (SN66752) and infused into Stoneville 213 and Acala SJ-2 acid-delinted seed of cotton (Gossypium hirsutum). The treatments appreciably reduced seedling disease in soil artificially infested with Rhizoctonia solani or Thielaviopsis basicola alone, in soil infested with R. solani and Fusarium spp., and in soil infested with a mixture of Pythium spp., R. solani, and T. basicola. None of the fungicides used alone consistently reduced seedling disease. With a few exceptions, methyl 1-(butylcarbamoyl)-2-benzimidazolecarbamate (benomyl) and methyl benzimidazolecarbamate HCl (MBC-HCl) did not enhance the efficacy of the three new systemic fungicides in reducing seedling damping-off, but their use reduced hypocotyl rot to some extent in the T. basicola-infested soil. The BAS 389 + CGA-48988 mixture in acetone was effective at 19 and 27 C and when plants were incubated at 27 C for 1 wk and then at 19 C for 4 wk. Application of BAS 389 in acetone mixtures with CGA-48988 or SN66752 tripled a stand of cotton (Acala SJ-2) in an artificially infested field plot at Beltsville and in a naturally infested plot in Louisiana. Application of BAS 389 alone with acetone was effective in the Beltsville plot, but not in the Louisiana field plot. Differences in stand among seed treatments in the field were less pronounced in naturally infested soil in Texas than in the other two locations. Benomyl and MBC-HCl did not improve seedling stand in the field. Phytotoxicity symptoms were not evident in the field tests.