First report of cotton blue disease in the United States
Lawrence took samples and sent them to Judith K. Brown at the University of Arizona. After 7 months of research, Brown connected the symptoms to cotton blue disease, caused by Cotton leafroll dwarf virus (CLRDV). The disease had never been seen in the United States. It was first reported in Africa in 1949 and then not again until 2005, when it was reported in Brazil.
Reported from six counties in coastal Alabama in 2017, cotton blue disease affected approximately 25% of the state’s cotton crop and caused a 4% yield loss. The disease was reported again in 2018, affecting 3-100% of cotton fields in Alabama but causing only a 1% yield loss.
Symptoms, which include slowed plant growth, loss of chlorophyll, and dwarfing of infected leaves, usually do not appear until last August after full bloom. To date, there are no recommended strategies for management of this disease.