Almond Facts, May-June 2021

IN YOUR ORCHARD THE ALMOND BOARD Mating Disruption Can Improve ROI, Reduce NOW Damage Navel orangeworm (NOW) damage often delivers the single largest pest headache for growers: NOW presence in the orchard can lead to an increased risk of aflatoxin residue and nut damage, which often translates to lower grades and ultimately lower payments to you, the grower. Two recently published research studies show that almond growers who add mating disruption to their Integrated Pest Management (IPM) strategy to fight NOW may be able to both reduce the number of times they spray in a season and improve their bottom line. In most cases, the investment in equipment that interrupts the mating cycle of NOW moths more than pays for itself with quantifiable reductions in kernel damage. Ins and Outs of Mating Disruption NOW larvae overwinter in mummy nuts and become adults in the spring when they start reproducing. Each generation of adults is called a “flight,” and typically there are up to four flights during one growing season. Historically, growers have timed sprays to the period when adults in each flight begin to lay eggs. Mating disruption involves the use of pheromones that imitate those used by female moths to attract male moths. The pheromones can be introduced to the orchard via strips placed in trees (roughly 18 to 25 strips per acre) or by hanging dispensers (one per acre) that release pheromone from aerosolized cans. Some of the more sophisticated — and expensive — systems include camera traps and weather stations that are used to further refine the timing of the release of pheromone to when the pests are most active. Senior Specialist in Pest Management at the Almond Board of California (ABC) Drew Wolter said mating disruption can provide an additional layer of protection for growers who rely on spraying. “If you’re just spraying, the chance of hitting every moth is pretty low — the moths are still mating, and they’re still laying eggs,” he explained. “Mating disruption allows you to reduce the population size at the first, second, third and fourth flight.” Research Compares Four Mating Disruption Systems In 2017 and 2018, University of California Cooperative Extension (UCCE) entomologist and farm advisor David Haviland and his team conducted ABC-funded research that provides quantitative estimates of the impact of mating disruption on NOW management. The first study evaluated the impact of four different mating disruption systems on NOW trap captures and damage. The second study used nine sets of paired orchards, ranging in size from 40 to 100 acres, to compare the impact of traditional insecticide programs with and without the addition of mating disruption. While evaluating the study results, researchers discovered the following key takeaways: • All four commercial mating disruption systems led to a measurable decrease in kernel damage. • The cost of mating disruption equipment was often more than offset by the increase in nut value — on average, implementation of mating disruption cost $127 per acre, while the average crop value increases were $144 to $150 per acre. • Mating disruption paid for itself in orchards averaging 1% damage, primarily by qualifying growers for increases in per-pound premiums. i In addition, researchers discovered a sharp reduction — as high as 94% — in the number of male moths caught in pheromone traps in orchards using mating disruption. 4 0 A L M O N D F A C T S