Submitted to: National Cotton Council Beltwide Cotton Conference
Publication Type: Abstract Only
Publication Acceptance Date: 1/9/2001
Publication Date: N/A
Technical Abstract: During the 2000 growing season, cotton field soils (Lufkin fine sandy loam) in the College Station, Texas area were found to be infested with oospores of Pythium aphanidermatum. Seedlings from wheat bran + peat moss coated seed suffered nearly 100% damping-off, but seedlings from nontreated seed rarely showed symptoms of the disease. Seed treatment with wheat bran + peat moss biocontrol preparations of Trichoderma virens appeared to control the disease. However, in soil amended with 1% wheat bran + peat moss just prior to planting, the biocontrol seed treatments were ineffective. Soil amendment with 1% ground corn stalks or cow manure did not enhance disease development as well as wheat bran did. Wheat bran amendment of field soil not infested with P. ahanidermatum oospores did not enhance seedling disease development. Assay of water extracts of soil, corn stalks, cow manure or wheat bran for effect on P. aphanidermatum oospore germination showed that only treatment with wheat bran extract significantly stimulated germination of oospores. Planting of cotton seed immediately after amendment of infested soil with wheat bran resulted in almost 100% kill of the seedlings. However, if wheat bran amended and infested soil was incubated at 25 degrees C for 3-5 days prior to planting, very little seedling disease was observed. Observation of the growth and development of cotton plants in soil infested or not infested with P. aphanidermatum but with equivalent fertilization, showed that plant growth was much better in noninfested soil than in soil infested with the pathogen. Plate assay of roots of cotton plants harvested from infested soil showed colonies of P. aphanidermatum growing from them, while roots of plants taken from non-infested soil did not.