A SPECIAL GROWERS’ REPORT OF AG ALERT ® CALIFORNIA Trees & Vines ®
A “mummy shake” takes place in Manteca to sanitize an orchard for the dormant season. Shaking the trees removes remaining almond mummies that can become a food source for overwintering pests.
Orchard sanitation key to thwarting new beetle pest By Vicky Boyd A small beetle that is a top almond pest in Australia has been found infesting almonds and pistachios in the San Joaquin Valley. C. truncatus is closely related to C. hemipterus, the dried-fruit beetle that infests figs and raisins after harvest.
So far, Wilson and his colleagues have confirmed C. truncatus in Stanislaus, Madera, Merced and Kings counties, which he said suggests it is already widespread. In addition, they have samples collected in Merced County in 2022, indicating it has been in the state for at least a year. Bob Klein, California Pistachio Research Board manager, said he doesn’t know how extensive the pest is in pistachios, but it started showing up as early as 2017. “The question is why did it show up at the levels it has this year?” Klein said about the beetle. “Almonds had a bad year with (navel orangeworm), so the speculation is that winter sanitation wasn’t done with the same stringency as it was in the past due to the wet weather and low prices, and insecticides weren’t used as much for (navel orangeworm) control. That may have led to an increase in the beetle population.” Following the discovery of carpophilus beetle in September, Wilson partnered with other farm advisors to conduct a broader survey of orchards across the San Joaquin Valley to determine the extent of the infestation. The survey team includes Jhalendra Rijal, a UCCE integrated pest management advisor for the northern San Joaquin Valley, and David Haviland, a UCCE farm advisor in Kern County. So far, researchers have collected samples from almonds, pistachios, walnuts and pecans, the latter two prompted by reports of C. truncatus infesting walnuts in See BEETLE, Page 7
Until more is known about the behavior of the carpophilus beetle in California, univer- sity entomologists recommend the state’s growers adopt Australia’s primary management strategy of winter sanitation. It involves shaking trees to remove nuts left after harvest, or mummies, where the pest can overwinter. Equally important is windrowing the shaken mummies, then shredding or chopping them. “Winter sanitation is going to be critical,” said Houston Wilson, an associate Cooperative Extension specialist with the University of California, Riverside. This is the same practice that is the foundation of navel orangeworm management in tree nuts. Wilson first learned about the beetle when a pest control advisor alerted Madera County orchard-systems advisor Phoebe Gordon to some strange almond damage in September 2023. At the time, the PCA thought it might be caused by twig borer. When Wilson visited the orchard, the grower recalled complaints from his nut processor about bad ant damage. A short time later, Wilson received a pistachio sample from Kings County that was also infested with the beetle. The California Department of Food and Agriculture identified the culprit as Carpophilus truncatus, which has been a well-established pest in Australian almond orchards for about 10 years. In that country, it has been reported frequently causing 3% to 5% kernel damage.
6 Ag Alert December 20, 2023
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