Submitted to: World Cotton Research Conference Proceedings
Publication Type: Proceedings
Publication Acceptance Date: June 7, 2007
Publication Date: March 10, 2009
Citation: Bennett, R., Davis, R., Hutmacher, R.B. 2009. Fusarium oxysporum f. sp. vasinfectum Race 4 in California. World Cotton Research Conferences - 4 Proceedings; paper #1383, CDROM.)
A brief review of research on Fusarium oxysporum Schlechtend.:Fr. f. sp. vasinfectum (Atk.) W.C. Snyder & H.N. Hans. race 4 in California is presented. Fusarium wilt has recently emerged as the dominant disease concern for cotton (Gossypium hirsutum L., G. barbadense L.) growers in California. An especially virulent form of F. oxysporum f. sp. vasinfectum was discovered in 2001 and has since spread to major cotton-producing counties in the San Joaquin Valley. Pathogenicity tests and genetic analyses revealed the causal agent to be F. oxysporum f. sp. vasinfectum race 4, a race originally described from India in 1960. Screening trials conducted since 2003 have shown that nearly all of the commercially available G. barbadense varieties are highly susceptible, and that many varieties of G. hirsutum also exhibit significant disease symptoms under certain conditions. Race 4 infection in acid-delinted cottonseed has been observed, however, seed infection in California cotton appears to occur at very low frequencies, possibly because of the arid production environment. Diagnostic tools such as race 4-specific PCR primers and macroarrays for the rapid identification of all known lineages of F. oxysporum f. sp. vasinfectum have been developed. These tools should be helpful in efforts to detect and quantify F. oxysporum f. sp. vasinfectum from plant tissue and soil.