Washington State University Prosser Extension Entomology Professor Doug Walsh Wednesday morning explained to Sunnyside Daybreak Rotary members how weather conditions in the Yakima Valley and Walla Wall area reduce the need for pesticide and fungicide use.
He said there has been research during the past 10 years showing the region's climate reduces the number of pests seen in the region, stating there has been an 87 percent reduction of pesticide use and 73 percent reduction of fungicide use in Washington.
Walsh said Gary Grove, who is a plant pathologist at the extension office, has been working on research to reduce powdery mildew, one of the leading pests afflicting crops in the area.
He said more than 75 percent of pesticides utilized in the region are for the control of powdery mildew.
Deficit drip irrigation, according to Walsh, has helped to prevent other pests. The dry climate combined with the irrigation prevents pests seen in Oregon's Willamette Valley and California vineyards.
He said Grove has set up a series of weather stations throughout the region to detect hot spots for powdery mildew. As a result, growers and fieldmen are able to receive data via a palm pilot or computer, warning them of conditions that may be suitable for the pest. The data provided also includes a list of fungicides that can be applied to crops.
Because of this technology, the Yakima Valley is down to four applications per growing season and the Walla Walla area is down to one application, on average, per season, according to Walsh.
He said Grove has also set spore traps within vineyards to determine which species of powdery mildew is in the vineyards.
Walsh has also conducted research on the cut worm, a pest that lives in vineyards through winter and eats new buds as they emerge.
He said the problem with traditional pesticides when combating the pest was the fact that beneficial insects were highly affected. "The pests typically regenerate faster than the 'good' bugs," he stated.
Through his research, Walsh is working to develop applications that will lessen the effects on beneficial insects.
He said the Den Hoeds developed a targeted barrier sprayer, which sprays a layer of pesticide at the trunk. Beneficial insects are able to survive above the area where a pesticide, typically a pyrethroid, is applied. The pests come in contact with the barrier and commonly will return to the soil.
Walsh said the problem with the use of pyrethroids is the fact that Europe does not like them. This has led to research for alternatives.
This past March, Walsh began examining several alternatives to the use of pyrethroids and discovered the use of hot pepper wax on a snap bracelet applied to the trunk of grape vines was effective in preventing pests, such as the cut worm from damaging crops.
He said another pest he has been researching has been the grape mealy bug. This bug causes grapevine leafroll disease.
The disease is a complex of viruses that plug a plant's water intake abilities, according to Walsh.
He said his research has shown the methods being utilized in controlling cut worms have been effective in reducing the grape mealybug populations.
"Beneficials are able to keep the mealybugs under control, as a result," Walsh stated.
The concern with mealybugs is the introduction of vine mealybugs, which Walsh said are more aggressive than grape mealybugs.
He said the vine mealybugs, indiginous to the Carribean, are being found in California vineyards. "It would take a very cold winter to kill them," he noted, stating the vine mealybug is known to eat the root systems of grape vineyards.
Another Carribean pest being watched closely is the glassywing sharpshooter. Walsh said this pest uses citrus as an alternative food source and causes Pierce's Disease, effectively killing vines.
He said the pest would be able to persist in Washington, however Pierce's Disease would not survive the winter climates.
Overall, Walsh said Washington's grape and wine industry uses fewer pesticides and fungicides than other states because of the climate, and the use of technology is helping to further reduce the use of both.