Soil Amendment and Biofumigation Effects on Cotton Root Rot Suppression.

Cotton root rot disease (Phymatotrichopsis Omnivora) is a major problem on cotton grown on alkaline-calcareous soils in Texas, other states in the southwestern U.S. and Mexico.  Research studies were conducted to develop economically feasible methods to suppress Phymatotrichopsis root rot (PRR) since complete eradication of this disease appears highly unlikely.  Field experiments have been conducted on soils extending from the lower Rio Grande Valley through the Coastal Bend of South Texas and West Central Texas.  Soil pH suppression, chelated trace elements, controlled release fungicide (CRF) and biofumigation treatments have been evaluated for efficacy in PRR suppression.  Early results indicate powdered S, chelated Fe, and CRF reduced plant mortalities 62, 13 and 57% below those from untreated check, respectively.   Use of biofumigation from a winter cover crop has produced limited and variable results the past two years.  This study showed remote sensing as a tool in estimating distribution of the disease.