It was two weeks late getting started, but the Kern County almond harvest is moving into full swing, says PCA Alan Butterfield, who works with growers in the eastern side of Kern and Tulare counties.
“The late start puts a lot of pressure on growers,” he says. “They’ll have to work very fast and efficiently to get the crop in before the fall rains come.”
In the second week of August one of Butterfield’s clients was spraying trees for mites, after being surprised by a late influx.
He attributes this late-season surge to insufficient predators to keep the spider mites in check.
“I don’t think we had much buildup of predators earlier in the year,” he says. “So, when the weather turned hot, the mites came on strong, and there weren’t enough predators to hold them back.”
Butterfield had hoped to spray for mites just once this year. But, because late-season mites reproduce at a faster rate than spring or early summer generations, a second August treatment was required.
In early August, he set out more freshly-baited navel orangeworm (NOW) traps and was examining the hulls and sutures, looking for eggs.
“We’re watching very carefully for navel orangeworm,” he says. “Trapping isn’t a really good indicator of the threat from this third generation. The flight this year was so erratic that we haven’t been able to get a good reading on degree days. We hadn’t seen any activity by the middle of the month — but we want to be ready to take action if necessary.”
Because of the difficulty in getting equipment into nut-laden orchards this time of year, spraying to control NOW is not very effective, Butterfield says.
“If the third flight comes on in the soft shell varieties, the best thing we can do is to drop the nuts and get them stockpiled and fumigated as quickly as possible.”
He and his growers were also on alert for various diseases, like alternaria, rust and scab. “We’re really watching for hull rot,” he says. “We’ve seen it develop pretty fast in some orchards.”
Applications of fungicides early this summer have controlled these diseases, but problems have occurred in orchards where preventive treatments were not made.
“There is quite a bit of disease inoculum in the orchards,” Butterfield says. “The only option we have now is to control humidity by continuing to cut water back as much as we can and irrigating only at night.”