How We Grow

2021 Sept/Oct How We Grow

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How harvest sampling results can help Continued improvement to IPM programs can be achieved by taking the time to interpret results from your post-harvest samples. IPM does not need to be a formula that is prescriptively and uniformly applied to every block. Rather it be a set of principles that guide practitioners to adapt according to the orchard's needs, through both proactive preventative measures and responsive pest management strategies, incorporating options that are appropriate for their situation. For example, true bug infestations can vary between the edges and interiors of an orchard – knowing the history of damage helps to address potential risks. If your records indicate that leaffooted bug or BMSB damage is greatest in samples taken from the north-west corner of a block closest to your warehouse and wood piles, which provide plenty of overwintering shelter and dwindles as you head south-east, you can adjust your management program to account for that spatial variability. Adjustments in this case includes the need for an increase in pest monitoring in that section of the orchard. Regularly monitoring this section of the orchard for pest occurrence and spread is an effective way of managing these pests. Early detection in this case can help address the pest situation by applying a low-cost spot treatment. When pest infestations continue to grow, regular monitoring is necessary to assess the damage and determine the time to initiate orchard-wide control. Monitoring is also important to avoid calendar- based pesticide applications especially at lower pest populations that do not warrant treatments. Similarly, if your historical records indicate that NOW damage is greatest in the eastern side of a block closest to a riparian corridor with black walnuts and oaks, prime overwintering habitat for NOW, you can make a few key adjustments to your NOW IPM program. First, pay close attention to your sanitation efforts, making sure that trees in this section of the block are particularly well sanitized during the winter months, targeting fewer than two mummies per tree. Next, look to increase your mating disruption and trapping efforts along that border. By increasing mating disruption efforts along that riparian corridor of the block you can reduce the population size that moves into the orchard as the season progresses. Increased trapping efforts allows for tracking the development of generations, aka "flights," as they enter and migrate into your orchard. This information will allow for the proper adjustments to the timing of treatments and perhaps the total number of sprays needed in Pest Description Ants In severe cases, nut meat will be hollowed out leaving only the kernels skin. Key signs: Shriveled kernels, sanded or stripped kernel skins, sawdust-like residue, without the presence of webbings and white frass (Figure 3). Navel orangeworm NOW creates deep feeding tunnels throughout the kernel. Key signs: White frass and webbings on the kernel (Figure 2). Leaffooted bug / BMSB Leaffooted bug feeding can result in dark spots on the surface of kernels. BMSB can feed later into the season creating black necrotic tissue on the kernel that appears sunken. Key signs: Pitting, stippling and dark necrotic tissue (Figure 4). According to Dr. Jhalendra Rijal, UCCE Area IPM Advisor, soft shell varieties such as Fritz, Sonora, Aldrich, Livingston, Monterey and Peerless are more susceptible to bug damage throughout most of the season. ALMOND ORCHARD 2025 GOAL Sawdust-like residue left by Southern Fire Ant feeding damage. Photo courtesy of Jack Kelly Clark, University of California Statewide IPM Program Figure 3 Continue on page 9 Almond Board of California 8

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