Distribution and Symptomology From CLRDV: An Alabama Perspective
By Austin Hagan, Ph.D.
Department of Entomology and Plant Pathology
Alabama Cooperative Extension System
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Cotton leafroll dwarf virus (CLRDV), an aphid-vectored virus, is the causal agent of the emerging cotton leafroll dwarf disease (CLRDD), which has been confirmed in nearly all cotton-producing states in the southern United States. First confirmed in Alabama cotton in 2017, this disease was diagnosed in 2019 in cotton collected in 46 of 67 Alabama counties and may cause yield losses in excess of 20% in selected cotton fields. Symptom expression and severity differs considerably by time of infection, host fertility status, and cotton cultivar. Winter weed hosts for CLRDV include carpetweed, evening primrose, henbit, and white clover; however, their importance in the epidemiology of CLRDD has yet to be established. Preliminary field trial results indicate that planting cotton early may be a strategy for avoiding CLRDD-related yield losses. Another suggested management option is either postemergence herbicide application or deep tillage for winter weed control. Efforts to identify resistant or immune cotton breeding lines and cultivars have begun.