Issue link: https://www.e-digitaleditions.com/i/1463529
2 The six-spotted thrips yellow monitoring cards, called a "Predator Trap," are available at Great Lakes IPM: https://www.greatlakesipm.com/ PEST MANAGEMENT mites, that means the presence of its natural predator – the six-spotted thrips. The highly mobile insect, marked with six distinct brown spots across its back, is specialized to eat spider mites and thrives in hot conditions. Haviland noted the six- spotted thrips are "excellent biocontrol organisms," with females making up about 90% of the population that can double its size every four days. "If biological control (six-spotted thrips) is present in the orchard, then spray treatments are not needed until you have about 40% of the leaves infested," Haviland said. Determining if six-spotted thrips are present in an orchard can be accomplished by using a yellow three- by-five sticky card trap. 2 The traps are hung in the orchard for one week to track the thrips population, which helps inform spray thresholds. "We've done a lot of work with these traps, including thousands of measurements," Haviland said. "If you want to know how many mites you have, count the mites. If you want to know how many mites there are going to be, count the thrips." Haviland said that during May spray timing, treatment is not necessary if mite infestation is below 40% and coupled with the presence of thrips – just 0.6 thrips per card per week. "In other words, if you're finding at least one thrips on a card in April and May – and you're below the 40% treatment threshold – you have double confirmation not to put on a May spray," Haviland said. "What we're finding is there is no longer a need for May sprays. Every time we try them, there is no real benefit. And every time we look for thrips in April and May, they are consistently present at levels above the threshold. The only exceptions are in baby trees where biocontrol has not had time to get established, or in cases where spring treatments for leaffooted bugs negatively affected the thrips. Outside those exceptions, the increasingly 'green' and 'sustainable' way almonds are being grown has allowed thrips to cause May sprays for spider mites to become a thing of the past." According to Haviland, the 40% leaf infestation threshold also applies during hull split. Research found that during hull split, the presence of three thrips per monitoring card showed no change in mite density over 14 days, with mite density lower after two weeks in 77% of orchards studied. "Based on the research, we recommend three thrips per card as a nice threshold if you're in hull split," Haviland said. "If you're seeing some mites during hull split and thinking about spraying, but you're also seeing three thrips per card in a week, walk away – you don't need to treat. However, if you're at treatment threshold and you're not seeing thrips on the card, that's justification for a miticide and there's a lot of options available." On the rise: leaffooted bug damage With kernel damage from leaffooted bugs on the rise, ABC is investing in ongoing research to develop a monitoring protocol and better tools to combat the pest, with the goal of developing clear treatment thresholds similar to those established for spider mites. "We're early in the process of developing the tools growers need to fight back against leaffooted bugs," said Drew Wolter, former senior specialist of pest management at ABC. "We've listened to the industry and we're investing in solutions." Leaffooted bugs can feed on young nuts before the shell hardens, causing the "We've done a lot of work with these traps, including thousands of measurements. If you want to know how many mites you have, count the mites. If you want to know how many mites there are going to be, count the thrips." — David Haviland Continued from page 2 Leaffooted Bug 3