Hot Water Treatments for Disinfesting Cottonseed of Fusarium Oxysporum f Sp Vasinfectum

Abstract: Fusarium wilt caused by Fusarium oxysporum f. sp. vasinfectum race 4 is found in an increasing number of fields in California, due at least in part, to seedborne dissemination. The disease is very difficult to manage and once a field becomes infested, there are no effective means to eradicate the pathogen from the soil. Detection of the pathogen in seed is possible with race 4-specific primers, but due to the relatively large size of cotton seed and the high plant densities used in cotton production, sampling a seedlot makes seed assays problematic. We are currently working on a hot water seed treatment to reduce the incidence of the fungus in seed. A series of hot water treatments (55, 60, 65, 70, 90 ºC) for various lengths of time were evaluated. Acid-delinted cottonseed of both Upland and Pima varieties, which had been stored for various lengths of  time, were used. Seed of all tested varieties remained viable and lost no seedling vigor after immersion in hot water at 60°C for 20 minutes. The ability of this treatment and others to reduce viability of Fusarium oxysporum f. sp. vasinfectum in seed is underway.