Plant Pathology

Dr. Bob Hutmacher, Univ. of California Cotton Specialist, showing damage from Fusarium oxysporum f. sp. vasinfectum race 4 (FOV4) in the San Joaquin Valley. FOV4 poses a strategic threat to U.S. Cotton Production Beltwide.


In addition to parasitic nematodes, cotton is subject to endemic bacterial, fungal, and viral diseases and at least two recently introduced fungal diseases. Bacterial Blight was well controlled by host-plant resistance breeding done at Oklahoma State and Texas A&M Universities, but is resurging. Target Spot, a tropical disease of rubber, is now a significant disease of cotton in the South Atlantic and Gulf Coastal regions, and sporadically occurs in the Mid-South. Fusarium wilt is now represented in the U. S. by at least four races (one very likely introduced) and two new, unclassified biotypes in East. Some of these new FOV races and biotypes are root rotting fungi that attack cotton at or before the six leaf stage and have necessitated new protocols for production of disease-free seed. An outstanding success has been discovery and implementation of fungicidal control  of Texas Root Rot, a soil-borne disease that otherwise defied a research solution for over 100 years.


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