Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/10/2008
Publication Date: 12/1/2008
Citation: Peterson, G.L., Kosta, K.L., Glenn, D.L., Phillips, J.G. 2008. Utilization of soil solarization for eliminating viable Tilletia indica teliospores from Arizona wheat fields. Plant Disease. 92:1604-1610. Interpretive Summary: At the request of the USDA Animal and Plant Health Inspection Service and the California Department of Agriculture, a study was initiated to determine if soil solarization of wheat fields infested with spores of Tilletia indica, the causal agent of Karnal bunt of wheat, could be used as a method for the deregulation of these fields and the required 3-mile buffer zone that surrounds them. Results showed that soil solarization significantly reduced the population of teliospores in the soil with results comparable to that of soil fumigation with methyl bromide, which had previously been used to deter regulation. Results support the feasible use of soil solarization as a potential tool for deregulating fields infested with teliospores of the Karnal bunt fungus.
Technical Abstract: Studies were conducted in Arizona to determine the efficacy of soil solarization for killing teliospores of the soilborne fungal wheat pathogen, Tilletia indica Mitra. In a replicated study, conducted in each of three years, T. indica teliospores and bunted wheat kernels were buried in a non-preirrigated Karnal bunt infested wheat field at depths of 5, 10 and 20 cm. Replicate samples were removed from under a clear plastic solarization cover at 7-day intervals and the number of viable teliospores determined. Results showed a rapid decline in teliospore viability at all treatment depths over 38 days, with efficacy comparable to methyl bromide protocols using clear plastic sheeting. Initial viability rates of 43, 71, and 82 percent germination were reduced to 0.1, 7.7 and 0.2 percent after 38 days (across all depths) in 2003, 2005, and 2006, respectively. Mean daily maximum soil temperatures at 5 and 20 cm under clear plastic in 2003, 2005 and 2006, were 67, 53 and 60C and 43, 38 and 43C, respectively. Under current USDA disease management strategies, the method may be useful for the rapid deregulation of Karnal bunt affected fields.