Growers are beginning to prepare local fields for fall melons, and with that comes the threat of cucurbit yellow stunting disorder virus (CYSDV). The virus was first identified in desert melons in the fall of 2006 where widespread infection on cantaloupes, honeydews and other melons cost growers a significant portion of their crops. USDA statistics suggest that fall melon yields in Arizona have declined considerably compared to years before the virus was introduced into the state. Without question, yields and quality in desert melon crops have suffered as a result of CYSDV infection. Additionally, melon pest management has been effected by CYSDV as insecticide usage on fall melons has increased significantly since 2006. Over the past six years we have been studying the virus and trying to understand its epidemiology and impact on fall melon production. In addition, we continue to develop new information on control of the vector of CYSDV (Bemisia whitefly adults). Whitefly numbers this spring and summer have been relatively light and the incidence of CYSDV on spring melons was relatively low. However, how this translates into virus incidence this fall is anybody’s guess. Given the aggressive management programs that PCAs and growers are now using, it will be interesting to see how CYSDV impacts melon production this fall. Our research to date suggests that fall melons produced near cotton or near areas where melons were produced the previous spring are at a high risk of infection. When possible, growers should attempt to isolate fall plantings as far away as possible from these sources of whiteflies and CYSDV. Growers forced to plant fall melons near these crops should be vigilant in minimizing adult whitefly infestation levels during pre-bloom growth stages. To view a summary of our research that details our findings visit our report on the Area-wide Incidence of Whiteflies and CYSDV in Yuma County, 2007-2012.

Remember: “ When in Doubt…… Scout”

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To contact John Palumbo go to: jpalumbo@ag.arizona.edu

For questions or comments on any of the topics please contact Marco Pena at the Yuma Agricultural Center.
College of Agriculture, The University of Arizona, Tucson, AZ.