VIEW ARTICLE

Changes in Carbon Dioxide Levels During Sclerotial Formation by Phymatotrichum omnivorum. Stuart D. Lyda, Associate Professor, Department of Plant Sciences, Texas A&M University, College Station, Texas 77843; Earl Burnett, Research Soil Scientist, USDA, ARS, Blackland Conservation Research Center, Temple, Texas 76501. Phytopathology 61:858-861. Accepted for publication 23 February 1971. DOI: 10.1094/Phyto-61-858.

Carbon dioxide was monitored over a 12-week period from pint-sized culture chambers supporting sclerotial formation by Phymatotrichum omnivorum on a sterile soil-sorghum seed substrate. Carbon dioxide accumulated rapidly during the first 2 weeks after inoculation with the fungus, and declined rapidly during the period of maximum sclerotial development. Sclerotial initiation coincided with the elevated CO₂ concentration, whereas maximum sclerotial dry weight was obtained in 8 weeks. Apparently, CO₂ or the dissolved bicarbonate ion influences sclerotial formation in P. omnivorum. Soils with the capacity to absorb or otherwise accumulate high concentrations of CO₂ or bicarbonate might be suitable for sclerotial development of P. omnivorum and support the cotton disease caused by this fungus. There were no significant changes in O₂ and N₂ levels during the 12-week study period.