Submitted to: National Cotton Council Beltwide Cotton Conference
Publication Type: Proceedings
Publication Acceptance Date: 1/16/2003
Publication Date: 2/19/2003
Citation: HOWELL, C.R. PRE-EMERGENCE DAMPING-OFF OF COTTON SEEDLINGS BY PYTHIUM SPP. AND RHIZOPUS ORYZAE. CD-ROM. NATIONAL COTTON COUNCIL BELTWIDE COTTON CONFERENCES. 2003.
Technical Abstract: Pre-emergence damping-off of cotton seedlings can be attributed mainly to three different soilborne pathogens. These are Pythium ultimum, Pythium aphanidermatum, and Rhizopus oryzae. During early planting when the soil is moist and the soil temperature is 60 to 60 degrees F, P. ultimum is the major pathogen isolated from diseased seeds and seedlings. In later plantings where the soil temperature is 70 to 75 degrees F, most pre-emergence damping-off is incited by either P. aphanidermatum or R. orzae. If only P. ultimum is present in the soil, planting in warmer soil will be of benefit. However, if either of the other two pathogens are present, later planting will be of little benefit. Disease incited by the Pythium spp. can be controlled by seed treatment with metalaxyl or other fungicides designed to control water molds. However, these fungicides do not inhibit R. oryzae, and seed treatments with fungicides containing PCNB are necessary in order to control disease incited by this fungus. Therefore, disease control when all these pathogens are present in the soil requires seed treatment with a combination of fungicides.