Donald Thomas hasn’t experienced much pressure from mites and leaffooted plant bugs this season in the tree nut orchards he works in the central San Joaquin Valley. However, sees the possibility of navel orangeworm numbers building to high levels in some almond orchards now that hulls have split.
“I think we have potential for a bad year for navel orangeworm,” he says.
He and wife Deborah own Advanced Agricultural Services, which serves growers in Fresno, Kings, and Tulare counties.
In early May, he saw his first mites of the season in an almond orchard near Fresno. That, plus the siting of the leaffooted plant bug, prompted the owner to spray the trees for both pests. “Sixty days later, we’re not seeing any mites or plant bugs return in that orchard,” Thomas says.
The mites he sees typically include brown mites, European red mites and web-spinning spider mites.
“Mite pressure is a little lighter this season than in the past few years, but they’re still present. You can drive by ranches in the Valley and easily see some trees suffering from what appears to be mite stress.”
One factor prompting Thomas’ concern about possible high navel orangeworm pressure in both almond and pistachios later this season is the consistency of trap counts he’s seen since the end of February. That’s when he first saw the moths laying eggs in warmer areas on the West Side near Kettleman City and Firebaugh.
“That’s a little earlier than usual,” he says. “Populations started building from there, although they remained light into May. In most cases, especially in pistachios, the numbers never went down completely to zero for any length of time. We’d spray and knock the numbers down, but they’d rapidly come back up to an average of 20 eggs per trap a week in some locations.”
As of the second week of July, he was finding navel orangeworm eggs on split hulls in Nonpareil. At the same time, he was also finding eggs and small worms in some pea-sized pistachio splits.
“Depending on where growers are in the central San Joaquin Valley, they probably have navel orangeworm in their trees now,” Thomas says.