Utilization of soil solarization for eliminating viable Tilletia indica teliospores from Arizona wheat fields

Authors: Peterson, Gary; Glenn, Deborah; KOSTA, KATHLEEN - CA. DEPT. OF FOOD & AGRI.

Submitted to: Phytopathology
Publication Type: Abstract Only
Publication Acceptance Date: 6/12/2007
Publication Date: 7/28/2007
Citation: Peterson, G.L., Glenn, D.L., Kosta, K.L. 2007. Utilization of soil solarization for eliminating viable Tilletia indica teliospores from Arizona wheat fields. Phytopathology. 97:S92.

Interpretive Summary:

Technical Abstract: Soil solarization was investigated as an alternative method for the deregulation of fields under management for Karnal bunt of wheat caused by Tilletia indica. Under the current USDA management scheme, infested fields and the surrounding 3-mile buffer area can be deregulated after 5 years of cultivation. An immediate method to kill teliospores in soil would eliminate the required 5-years of regulation and associated management costs. Although methyl bromide has been shown to reduce teliospore viability in soil; the ecological ramifications, costs, and eventual phase-out in the U.S. make it a poor choice. Studies were conducted in Arizona in 2003, 2005 and 2006 to determine the efficacy of soil solarization in killing teliospores. Teliospores or bunted kernels were buried in an infested wheat field at 5, 10 and 20 cm, and then covered with a clear plastic solarization tarp. Replicate samples were removed at 7 day intervals up to 38 days. The number of viable teliospores was determined by seeding extracted teliospores onto water agar plates. Initial viability rates of 43, 71, and 82% were reduced to 0.1, 7.7 and 0.2% after 38 days (across all depths) in 2003, 2004, and 2006, respectively. Mean maximum temperatures in 2003, 2005 and 2006 were 67, 56 and 60 C (5 cm) and 43, 41 and 43 C (20 cm), respectively.