Submitted to: Phytopathology
Publication Type: Abstract Only
Publication Acceptance Date: 6/12/2007
Publication Date: 7/1/2007
Citation: Bennett, R.S., Colyer, P.D. 2007. Dry heat treatment of Fusarium-infected cotton seed. Phytopathology. 97:S10.
Technical Abstract: Fusarium wilt caused by Fusarium oxysporum f. sp. vasinfectum (FOV) race 4 has emerged as the dominant disease concern for cotton growers in California. Originally described from Asia, race 4 has spread into multiple counties in the San Joaquin Valley (SJV) since its discovery in one California field in 2001. Because the SJV produces significant quantities of seed cotton and transmission of FOV through acid-delinted seed has been well established, there is an urgent need for an effective means of eliminating the fungus from infected seed. Since dry heat treatment has been shown to kill F. graminearum in small grains, the effects of four temperatures (50, 60, 70, 80 ºC) over 14 days on survival of Fusarium in acid-delinted cottonseed were tested. Seeds were placed on Komada's agar after dry heat treatment and assayed for Fusarium infection and seed germination. The percent of seed infected with Fusarium decreased from an initial level of 12-15% to 0-5% after two weeks of heat treatment. Fusarium was nearly eliminated after three days at 80 ºC; infection decreased more gradually with lower temperature treatments. Germination appeared to be unaffected by heat treatment, except at 80 ºC for longer than 11 days. Thermotherapy may be effective in preventing dissemination of FOV races to new areas via infected seed.