St. Paul, MN (October, 2019)--Cotton blue disease, caused by Cotton leafroll dwarf virus (CLRDV), was first reported in 1949 in the Central African Republic and then not again until 2005, when it was reported from Brazil.
In 2017, cotton blue disease was identified in Alabama, marking the first report in the United States.
Plant pathologists discovered foliar distortion and leaf curling and rolling on cotton in six counties in coastal Alabama.
They sent samples to University of Arizona plant pathologist Judith K. Brown, who originally suspected the causal agent to be a whitefly-transmitted geminivirus--the only type of virus known to infect cotton in the United States at that time.
However, after using the Illumina platform for discovery genomics to conduct next-generation sequencing, Brown determined that the symptoms were characteristic of cotton blue disease.
Characteristic symptoms of cotton blue disease include slowed plant growth and loss of chlorophyll, causing the yellowing or dwarfing of infected leaves and/or the entire plant.