Almond Facts, May-June 2021

“That number is massive,” Wolter said. “It means mating disruption confused males to the point that they didn’t mate, which leads to a decreased population. Generation by generation, their population declines.” Haviland’s research shows that mating disruption is effective across many almond varieties, reducing NOW damage by 65% and 78% in Nonpareil and pollinizer cultivars, respectively. A full version of the study report and additional findings may be viewed in the February 2021 issue of the Journal of Economic Entomology . ii “In general, NOW mating disruption in almonds can currently be viewed as an insurance policy against high losses from NOW,” the report states. “These results suggest that adding mating disruption to an existing navel orangeworm management program can be a cost-effective way to reduce damage while promoting sustainable management practices.” Study Suggests Best Results Require Mating Disruption and Spraying Bradley Higbee and Charles Burks authored the second NOW-related research study, which appears in the February 2021 issue of Insects iii . Higbee is a research and development manager at Trécé Inc., and Burks is a research entomologist for the U.S. Department of Agriculture Agricultural Research Service. Their research was conducted between 2006 and 2015 in an almond orchard of more than 2,000 acres in Lost Hills. The orchard’s varieties include Nonpareil, Monterey, Butte, Carmel, Fritz, Mission, Price, Ruby and Wood Colony. Intense winter sanitization, including machine and hand removal of mummy nuts and flail mowing, was practiced in all orchard blocks. Higbee and Burks found that “blocks treated with both mating disruption and insecticide had lower damage than those treated with either alone in nine of the 10 years” those orchard blocks were studied. In many years, the kernel damage was cut in half. “The fact that this study covers a 10-year span gives you a sense of the variability of high-pressure years and low-pressure years from navel orangeworm,” Wolter said. “There was a clear difference in combining mating disruption with spraying.” Wolter said for growers who often spray for NOW multiple times a year, a sound mating disruption program has the potential to eliminate treatments. Current research shows mating disruption can reduce the number of male moths caught in traps by 93.5%. “A proper mating disruption program is not intended to take away all spraying but could reduce the total number of sprays in a season,” he said, suggesting spraying is especially important at hull split when nuts are most vulnerable to egg-laying moths. In this study, doubling the number of mating disruption devices usually resulted in lower damage, but there was not always a statistical difference, which suggests that the This graph summarizes the research findings from Burks and Higbee’s research. iv NOW worm. Photo credit: The Almond Board of California 41 M A Y – J U N E 2 0 2 1