PCA Chris Morgner and his staff have been walking almond orchards throughout Merced and Madera counties almost on a daily basis looking for signs of leaffooted plant bug and stink bug. So far, no sign of the pests.
“Depending on the year, we’ve seen them show up any time from March through May,” says the owner of Agri-Valley Consulting, based in Merced, Calif. “However, the nuts are sizing up pretty nicely this year, so it shouldn’t be too long before we see them.”
PCA Andrea Gjerde, with Entomological Services, Inc., Visalia, Calif., hadn’t sighted either plant bug this season, either, as March drew to a close. Her responsibilities include an almond orchard in Kern County just north of Bakersfield. When she checked it the last week of March the flowers were coming off as the young fruit began to develop. “Last year was wet and cool, and we first saw the leaffooted plant bug there in the second week of April. Because of similar weather, I assume that’s about when we’ll see it this year.”
Neither leaffooted plant bugs nor stink bugs were much of a problem for either PCA in 2011. Last year, Gjerde recommended treating the Kern County orchard for leaffooted plant bug on May 2. Morgner sprayed one ranch in northwestern Fresno County for stink bugs on May 5 and another on the east side of Merced County for leaffooted plant bugs on May 20.
There were probably plenty of the bugs in the orchards last year, he says. However, the effect seemed to be limited. He suspects the number of nuts from the big almonds and pistachio crops diluted the pest’s impact.
The wary adult leaffooted plant bugs, which hide when they detect movement, prefer the tops of canopies. As a result, Morgner notes, they are hard to spot in trees that may stand 30-feet high. “When we see the adults, it’s more by accident,” he says. “The eggs, which are laid in strands on the fruit and leaves, are actually easier to see. Usually, we know they bugs are in an orchard by the evidence they leave, like tendrils of gum oozing out of the shells where the bugs pierced them with their mouth parts.”
Sometimes his growers find the bugs by flushing them out. “They’ll put a little insecticide in their sprayer and make a quick application, running up one row and back down the other. After several hours, we’ll come back and check the ground for any dead bugs.”
One year, a client didn’t discover leaffooted plant bugs until harvest. The grower had been watching his orchards carefully up to that point but had not detected any, Morgner recalls. Then, while harvesting his shaker operator saw the bugs coming out of the trees and crawling all over nuts on the ground that had been shaken loose.
“That’s why growers get paranoid about this particular bug,” Morgner says. “Often, it’s not really obvious that they’re in an orchard.”
Despite their presence in the trees the grower didn’t suffer any quality losses in that block, Morgner adds. “I don’t understand why,” he says. “The bug population must have built up after the nut were fully mature and were unable to do much damage to them,” he says.
The pressure Morgner has observed from the leaffooted plant bug and the stink bug has varied from year to year and between locations.
He scouts some orchards where the bugs show just about every spring and are treated annually to control the pests. In others, the bugs have never been a problem.
Often, stink bugs outnumber leaffooted bugs along the Interstate 5 corridor on the western side of the San Joaquin Valley, while leaffooted bugs are more prevalent than stink bugs along Highway 99 corridor on the east side. However, the situation can also reverse itself.
Regardless of when and where these pest show up, Morgner has no doubt about how growers should respond. “If you’re surveying your orchards regularly between March and the end of May and start finding the bugs or the damage they leave behind, you better take prompt action to control them,” he says “Otherwise, they can get out of hand quickly and cause a lot of damage.”