Issue link: https://www.e-digitaleditions.com/i/1328890
ALMOND ORCHARD 2025 GOAL Gary Osteen, a PCA with four decades of experience in Kern and Tulare counties, said he has also moved away from spring miticide sprays. "With material and application, it costs easily $75 to $100 per acre to spray. But if you don't need to apply it, why would you do it?" Osteen said. "Now, one spray at hull split has been the common amount used. I just don't spray that much in the spring anymore." Controlling mites at hull split Though spring miticides aren't needed most of the time, hull split is different. "Between hull split and harvest it is common for spider mites to reach treatable levels," Haviland said. "Growers are encouraged to use the 40% threshold (mites observed on 40% of leaves), while recognizing that often these thresholds are reached when pre-harvest intervals or harvest makes it impossible to treat." This means a grower needs to predict not just where mite levels are today, but what levels will look like a week or two later. Again, monitoring for thrips provides key data to inform that decision. "If you want to know how many mites there are today, count mites; but if you want to know how many mites there will be in the future, it's the number of predators that matters. Research has shown that if there are three six-spotted thrips per card from hull split through the end of harvest, mite populations will be the same or lower in 14 days," Haviland said. "So, if you have 30% of leaves with mites but 10 thrips per card, you can walk away and not spray." Conversely, no thrips on the sticky card spells trouble. "If it is hull split and you have 20%of leaves infested and zero thrips, and it's your last chance to spray, you should absolutely take advantage of your last opportunity to spray." Judicious use benefits all growers Threshold-based spraying not only allows growers to get more out of their beneficial insects while saving money on sprays, labor and regulatory compliance, but this technique also offers other benefits to individual growers and the broader industry, according to Drew Wolter, ABC's senior specialist in Pest Management. "Reducing our reliance on chemical applications helps maintain pesticide efficacy by reducing the development of resistance," he said. "It also helps achieve one of our industry's Almond Orchard 2025 Goals, which is to increase adoption of environmentally friendly pest management tools by 25 percent." UCCE entomologist and farm advisor David Haviland checks a predator trap in an almond orchard near Bakersfield. Hanging yellow sticky traps in the orchard is the most effective way to monitor insect predators of mites. Photo credit Petr Kosina Sticky Traps Subscribers to How We Grow received two sticky traps to try out in their orchard, courtesy of the Almond Board. In addition to the instructions provided in this article, growers are encouraged to read the tips provided on the card regarding placement, timing and UCCE guidelines for establishing treatment thresholds. "This is a great opportunity to try your hand at monitoring for beneficial insects like six- spotted thrips," Wolter said. Growers with questions about their individual orchard needs are encouraged to contact their local farm advisors. Almond Board of California 10