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2022 Midwest Vegetable Guide

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Insect Management Strategies Midwest Veg Guide 2022 69 Insect Management Strategies Reviewed by Laura Ingwell – September 2021 Effective insect, mite, and slug management relies on applying IPM strategies which include the following tools: 1. Preventive practices. 2. Properly identifying key pest insects, mites, slugs, and beneficial organisms. 3. Monitoring and early detection of insect, mite, and slug populations. 4. Determining the pest's economic loss potential 5. Selecting the proper pest control option. 6. Evaluating the effectiveness of employed control options. Preventive Insect Management Practices There are a number of practices that can reduce insect numbers before you actually see the insects in the crop. Often, decisions about these practices must be made based on past experience with the pest. Many of these practices are good management practices for weeds and diseases as well, so they can easily be incorporated into production practices that yield multiple benefits. Resistant Varieties: There are not many vegetable varieties that have been bred exclusively for insect resistance. However, there are many varieties that target resistance to insect-vectored plan pathogens. This information is often printed in seed catalogs or available directly from seed suppliers. Varieties that are resistant to pathogens may still sustain direct damage from the pest; ask your seed provider. The information on crop resistance to insects, mites, and slugs directly is harder to find. Some varieties of cabbage are resistant to onion thrips. Selection of sweet corn varieties that have husks that completely cover the ear tip and fit tightly around the ear can reduce the amount of corn earworm damage. Short season varieties of potatoes should be grown when possible to give Colorado potato beetles less time to feed and reproduce. This is not resistance, but it is a method that growers can use to reduce insect damage by varietal selection. Crop Rotation: Rotating crops can reduce the severity of a number of pest problems. Rotating potato fields can greatly increase the amount of time it takes Colorado potato beetles to colonize a field, thereby reducing the time the beetles have to damage the crop. Rotating cucurbit crops can be equally effective for cucumber beetle management. Don't plant crops that are susceptible to wireworm or white grub damage in fields that were previously in sod or heavily infested with grassy weeds. In addition, it is a good idea not to plant cabbage or onions next to small grain fields, because onion thrips build up to very high levels in small grains and may move into cabbage or onions when the small grains dry down or are harvested. The effectiveness of rotation for pest management relies on the host range of the pest (what crops can/does it feed on) and its dispersal capabilities (how far will it have to go to find a suitable host). Crop Refuse and Volunteer Destruction: Destroying the plant residue after harvest can reduce the damage experienced the next year from a number of insects. Destroying squash and pumpkin vines after completion of harvest can greatly reduce the overwintering population of squash bugs and squash vine borers. Early vine killing in potatoes will reduce the potato beetle populations for the following year. Volunteers that resprout from last year's crop can serve has a harborage and a source population for insect pests on field edges or as weeds in another crop, and should be destroyed. Tillage: Fields that receive reduced amounts of tillage or have some sort of grass windbreaks are often more susceptible to damage from insects such as cutworms and armyworms. These cultural practices may have other advantages that outweigh the potential insect problems, but growers should be aware of the potential for increased insect activity. Tillage can also be effective to directly damage insects that reside in the soil over winter or between crops. Time of Planting or Treatment: Many pest insects go through life according to heat units, and are subject to weather, just like plants. Growing Degree Day (GDD) models and weather forecasting tools have been developed for several pests that detail when they are likely to be at a stage that is damaging, or blow in from another area, or when they are at a life stage that is easy to control or avoid. Because insects tend to become active at specific times each year, varying the time of planting can sometimes help prevent serious insect problems. Corn earworms and fall armyworms are usually a much more serious problem on late-planted sweet corn. If the option is available, planting sweet corn so that it has no green silks before large numbers of earworm moths are flying can reduce earworm problems. Root maggots are usually more serious during cool, wet weather. Waiting until soil temperatures are adequate for rapid plant growth will help reduce maggot problems. Here are some resources for tracking weather and predictive models related to insect pests: • • •

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