As growers begin to prepare local fields for fall melons, they should be considering
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. Without
question, yields and quality in desert melon crops have been seriously affected
by CYSDV infection. Additionally, melon pest management has been affected by CYSDV
as insecticide usage on fall melons has increased significantly since 2006. Over
the past eight years we have been studying the epidemiology of CYSDV and trying
to develop approaches for reducing its 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 very moderate
to heavy and the incidence of CYSDV on spring melons was high on some late planted
spring melons. How this translates into virus incidence on fall melons is not certain,
but our experience suggests that you should anticipate risks from CYSDV to be as
high as previous years. Further, 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 spring melons were recently produced are at the highest
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 with insecticides during pre-bloom growth stages. To view a summary
the status of CYSDV in Yuma County and guidelines for management visit
2015 Guidelines for Whitefly and CYSDV Management on Melons.
