Summary:
Since the re-establishment of the USDA-ARS, WICS, genetic/breeding program, we have been focusing on bringing germplasm from any possible source available to us in order to increase genetic diversity. Most of the time, the genetic diversity in the cotton crop is used as an indicator to recognize potential threats to sustaining high yields. In the last couple of years, several troubling developments have recognized Fusarium oxysporum f.sp. vasirifectum (FOV) Atk. Sny & Hans as a recurring and potentially expanding threat to cotton production. The vulnerability of cotton production to this pathogen highlights the need for comprehensive research to protect the cotton industry from FOV, both from virulent populations which may be introduced and new virulent strains arising from within cotton production areas. Until recently, only race 1 and race 2 were known to occur in the United States (DeVay, 1986; Smith et al., 1981). UC scientists have recently identified race 4 ofFOV in cotton plants…