Virus striking melon plants in Yuma County, Sonora
by The Associated Press on Mar. 23, 2007, under LocalYUMA – Growers and researchers in Yuma County are scrambling to find a way to contain a virus that strikes melons and caused the loss of an estimated 50 percent to 75 percent of the fall crop.
The virus – cucurbit yellow stunting disorder virus, or CYSDV – first appeared in Yuma in the fall. It attacks all types of melons, plus squash, gourds and cucumbers.
CYSDV symptoms develop first on older leaves and the plant appears to need water. The leaves then yellow, and as the plant’s internal transport liquid system breaks down, it tries to save itself by dropping older leaves. But without enough leaves it can’t support and nourish the fruit.
“It’s devastating to melons,” said Kurt Nolte, agriculture agent with the Yuma County Cooperative Extension.
Researchers at the University of Arizona and agriculture officials from Yuma, Imperial County, Calif., and Sonora, Mexico, are working on ways to limit the spread.
The virus also has attacked plants across the border in Sonora.
Yuma’s fall melon crop is not very large, only about 800 acres, Nolte said, but the spring crop now growing is estimated at 3,000 acres.
Nolte said the source of the infection is unclear, but once introduced it is spread from plant to plant by the whitefly.
“It’s not a huge concern at the moment for the spring crop,” he said, because whitefly populations are low. But as temperatures rise, insect activity picks up and the disease can spread.
Some commercial melon growers have volunteered to harvest early and delay planting the fall crop to provide a “host-free” period.
“We hope to break the cycle of the virus spreading from melon to melon plant,” Nolte said. But even with the voluntary host-free period, the virus could survive in home gardens, or even on wild melon varieties in the desert.
