By
John Lindt
Tulare County's top ag pest watcher, biologist Dennis Haines, says farmers are welcoming the heat this month not just because it makes their fruit sweeter – it does – but because the 100-degree-plus temps are frying some of those new bugs that are preying on the trees and vines.
“It's not just the cold winters we need but hot temperatures too that will knock down the population” of persistent pests like the olive fruit fly, and keep threatening pests like the light brown apple moth knocking at our door, at bay.
“We have a light olive crop this year since its alternate bearing, and the good news is the heat has drastically reduced our olive fruit fly problem,” says Haines.
As for the light brown apple moth, the voracious bug has now been found near Manteca but it's mostly a problem on the coast, notes Haines. “They don't like the heat either.” Officials are concerned about the moth getting established here since it dines on most of our menu of crops.
Tulare County citrus growers are particularly worried about the spread of Asian citrus psyllid that can carry the dreaded citrus greening disease that has devastated groves around the world and is on a tear in Florida right now.
“We have extensive trapping
programs out there right now,” says Haines. The disease has now
been found in Georgia and in the Yucatan in recent weeks.
In response, UC Lindcove is protecting more of its tree bud wood under
a screen on the likelihood the bug will show up here. It's already in
Southern California. Other tropics based dangers are lurking including
West Nile Virus.
“All these vectors are knocking at our door,” shrugs Haines.
Researchers blame global warming in part for the surge in exotic pests that are dropping in for a meal – uninvited. In the most recent issue of the UC publication California Agriculture, a review by UC Riverside entomologist John Trumble and graduate student Casey Butler predicts that the numbers and kinds of invasive insect pests will increase because of rising temperatures. Pest insects will consume more of certain plants due to their higher carbon and lower nitrogen content, and the reduction in winter chill periods will allow pests to breed throughout the year.
Success Story
One bug that concerted action has succeeded in knocking down its damaging population is the Glassy-winged Sharpshooter, says Haines.
“We have a joint program between Fresno, Tulare and Kern counties that has been very effective.” The GWSS can carry the virulent Pierce's Disease that kills off grapevines.
The disease had taken a hold on vineyards in the Edison area in part because it was close to citrus growers – a favorite hangout for GWSS although they don't damage citrus. “They were already losing vineyards down there,” says Haines, before a full court press with the help of USDA and South Valley counties stemmed the spread of the disease. The upshot locally is that a growing population of the pest in the Porterville area a few years ago has been largely controlled.
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