|Howell, Charles - Charlie|
Submitted to: Journal of Cotton Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/3/1997
Publication Date: N/A
Interpretive Summary: The purpose of this research was to determine if combination biological and chemical seed treatments could effectively control cotton seedling diseases on different cotton varieties and under diverse environmental conditions. Field tests, over several years in California and in states of the Southern Cotton Belt, of combined biological and chemical cotton seed treatments have shown effective and consistent control of cotton seedling diseases. The biological component is the fungus Trichoderma virens, cultured on millet or wheat bran + peat moss, air-dried, and ground into fine granules. The chemical component is the fungicide metalaxyl. The seed are treated first with the fungicide, followed by a latex sticker and the fungus granules. Cotton seed treated with the biological/chemical combination and planted in soil heavily infested with seedling disease pathogens have produced stands equal to those obtained with standard fungicide treatments and significantly better than those from nontreated seed. Biological/chemical seed treatments may also provide longer term protection than that provided by fungicides alone, through colonization and protection of the developing root system and reduction of pathogen inoculum by parasitism of pathogen propagules in the soil.
Technical Abstract: Air-dried granular preparations made from culture solids of the biocontrol fungus Trichoderma virens give effective control of cotton seedling diseases when they are combined with metalaxyl and coated on cotton seed with a latex sticker. Shake cultures of the fungus grown on ground millet or wheat bran + peat moss produce large numbers of separate thick-walled chlamydospores when incubated at 27 C for 12 days. Field tests of T. virens/metalaxyl seed treatments in California and in other states of the Cotton Belt have resulted in seedling stands equal to that of chemical controls and significantly better than nontreated seed. The addition of Baytan or Maxim to the combination treatments did not confer any particular advantage with respect to seedling stand over the T. virens/metalaxyl treatment alone. Treatment of cotton seed with latex sticker, followed by shaking with air-dried fungus containing granules gave complete and uniform coverage of the seed, and very little loss of granules was observed during handling and packaging.