How We Grow

2021 Sept/Oct How We Grow

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Evaluating Management Programs Via Harvest Sampling Windrow sampling is part of an integrated pest management (IPM) model of continual improvement and two often overlooked components, evaluation and adaptation, can be added to post harvest activities. By the time harvest arrives, most pest management programs have been executed and is a perfect time to evaluate how these programs performed. Harvest (aka windrow) sampling is a great practice for growers and PCAs to assess strengths and weakness of each program. How are results from harvest sampling different from grade sheets? Grade sheets from the handler provide growers with information regarding relative damage, but not what specifically caused the damage. Harvest samples distinguish specific pest damage and the associated percentage of the damage in the samples. This aides in two crucial IPM steps: The ability to evaluate how successful individual pest management programs were during the last growing season. Harvest samples allow you to identify what caused the damage, and thus assess your management decisions, including the efficacy of the material applied, the timing of those treatments and how well your monitoring programs worked. Through this evaluation process, growers are able to develop historical records for each block. Over time, this provides valuable information, such as where infestations may be coming from and where perennial orchard hotspots are prevalent. This information allows you to adapt management programs according to potential risks and the orchard's specific patterns of infestation and pressure. All of this helps develop strategies for next year's integrated pest management program. How to conduct harvest sampling UC IPM guidelines for harvest sampling 1 recommend that 500 nuts per block should be taken; however, not every block has the same layout, pressure, size and neighboring conditions and the total number of samples should be adjusted accordingly. Larger blocks may require additional sampling to provide an accurate representation. The primary goal should be to obtain a representative sample from multiple areas within a block. If you know a block has historically shown high pressure, you can partition and denote which rows samples were taken from to gain more precise information. For example, you can take five 100 nut samples from five evenly spaced rows within a block. Because insect populations build over time and space in orchards, this method will give you more detailed information regarding where pressure is coming from. This can be time consuming during a busy time of the season for a grower. Fortunately, producers can store the samples in a cold room or freezer until harvest activities wind down and do the sampling during a less demanding time. Tips for identifying damage The main insect pests to keep an eye out for during damage assessments include navel orangeworm (NOW), ants, leaffooted bugs and brown marmorated stink bug (BMSB). DUST 1 UC IPM Harvest Sampling Guidelines: PMG/C003/m003hcharvstsmpl.html 2 Plant and Stink Bugs of Almond Orchard-Almond Variety susceptibility: https:// 1 2 Almond harvest pre windrowing. White frass and webbings on a kernel caused by navel orangeworm feeding. Figure 2 7

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