First Report of Fusarium Wilt of Cotton Caused byFusarium oxysporumf. sp.vasinfectumRace 4 in Texas, U.S.A

Abstract

Fusarium wilt of cotton (Gossypium spp.), caused by the soilborne fungus Fusarium oxysporum f. sp. vasinfectum (FOV), is a widespread and economically important disease. FOV is genetically diverse with numerous described races and genotypes (Cianchetta et al. 2015), most of which cause disease only in the presence of plant-pathogenic nematodes; however, FOV race 4 is extremely virulent and can cause severe, early-season damage in the absence of nematodes. Race 4 was first described in India (Armstrong and Armstrong, 1960) and has likely spread to other cotton-producing regions through cotton seed. FOV race 4 was first detected in California in 2001 (Kim at el. 2005), and had not been confirmed elsewhere in the U.S.A. (Cianchetta et al. 2015) until recently. In June of 2016 and 2017, severe Fusarium wilt symptoms, including wilting, root rot and stem discoloration, that were consistent with FOV race 4 were observed on seedlings of Pima cotton (Gossypium barbadense) in the Upper Rio Grande Valley of Texas i...