Leaffooted bugs overwinter on pomegranates and in other
Spring is a critical time to monitor and control overwintering leaffooted bugs that are moving into and feeding on developing almond nuts, resulting in crop losses from fruit drop.
This is particularly important in more susceptible almond varieties such as Fritz and Aldrich, and when the orchard has a history of leaffooted bug infestations. Adult leaffooted bugs overwinter in sheltered areas such as palm trees, junipers, pomegranates, citrus, olives and other popular overwintering food sources. Growers should monitor orchards postbloom and treat as necessary with a good contact material to knock down adult leaffooted populations.
UC Berkeley Extension entomologist Dr. Kent Daane said the key to understanding the potential for leaffooted bug damage in 2014 is to look back at 2013. If overwintering sites had large leaffooted bug populations in the fall, it is likely the pest will crop up in neighboring almond orchards without the benefit of a winter cold snap to kill off those overwintering pests.
Cold temperatures and rainfall from December to February can
reduce overwintering leaffooted bug populations. Still, where there is a history of the pest, growers from postbloom through April should monitor their orchards for presence of the pest and treat early to prevent fruit drop.
“Early control is absolutely vital to get those overwintering populations so that nuts don’t drop,” Dr. Daane said.
Monitoring in the south San Joaquin Valley typically should begin in mid-February and continue through April farther north into the Sacramento Valley.
There are not yet pheromones on the market to monitor leaffooted bugs, and sweep or beating tray samples are not reliable because adult insects scatter before they can be detected. Daane suggested using a long pole in mature orchards to beat the side and top of the canopy and watch for adult flyers.
“If you are near an overwintering population source and are worried based on past history about leaffooted bug, it is a good idea to sample once a week for four or five weeks once bloom is done and nuts are set,” he said.
Varieties such as Fritz and Aldrich are more susceptible to leaffooted bug damage, although the exact reasons are not understood. Growers with those orchards should be particularly vigilant this time of year. If pole sampling reveals adult flyers,
treat immediately with a newer generation pyrethroid or neonicotinoid.
A single application of these newer materials will usually control the pest. “Most importantly, use a material with good knockdown activity because if you keep them alive, it can quickly
result in crop damage,” Dr. Daane said.