Verticillium Wilt of Cotton

Verticillium wilt is one of the most important diseases of cotton worldwide. This disease was first reported on Upland cotton in Virginia in 1918. Currently, Verticillium wilt is widespread in most of the cotton belt region of the U.S. and causes great economic losses in some cotton producing areas such as western Texas and San Joaquin valley of California. In Arizona, Verticillium wilt occurs only on Upland cotton, especially more severe in the regions at elevations above 3,500 feet in Cochise, Graham, and Greenlee counties where cooler air temperatures (70 to 80 °F) are more favorable for symptom expression from late summer to fall. A recent study showed that overwatering and heavy soil with higher composition of silt and clay led to an increased in disease incidence (Land et al., 2017). With adoption of tolerant cultivars, Verticillium wilt has not been a major problem in Arizona cotton in the recent past.