Cotton Leaf Crumple Virus Incidence

Cotton leaf crumple virus is a geminivirus transmitted to cotton by the whitefly Bemisia tabaci. During 1992, the spatial pattern of whitefly populations levels (see figure) were monitored weekly by the USDA and the Arizona Cotton Research and Protection Council (ACRPC) (Nelson et al. 1993).  Whitefly trap locations were located on GIS maps and trap counts were analyzed using geostatistics to provide statewide maps of whitefly population levels. At the same time, the presence or absence of symptoms of cotton leaf crumple disease was recorded at all trap locations. The virus disease was highly restricted spatially (see figure), with no apparent relationship to the abundance of whiteflies on a regional scale. When there is a good whitefly host, such as cantaloupe, present early in the season, and a host for the virus present near a recently planted cotton field, unusually damaging infections of leaf crumple may result. 

Growers should focus attention on action at the local level to reduce alternate hosts for the virus and be aware of important local sources of high levels of whiteflies early in the season. A good overall management program for control of whiteflies is important but spraying insecticides for control of the virus disease is unwarranted and counter-productive. 

Nelson, M. R., Orum, T. V., Byrne, D. N., Osama, E. L., Antilla, L., and Staten, R. 1993. Preliminary investigation of sweet potato whitefly population dynamics across Arizona. Pages 197-205 in: Cotton Report 1993. J. Silvertooth, ed. Agricultural Experiment Station and Cooperative Extension Service, College of Agriculture, University of Arizona, Tucson.

Byrne, D. N., Rathman, R. J., Orum, T. V., and Palumbo, J. C. 1996. Localized migration and dispersal by the sweet potato whitefly, Bemisia tabaci. Oecologia 105:320-328.