What is integrated management?
Regardless of the size of a farm, crops grown, or growing practices, integrated pest management (IPM) is a framework that can be used by all growers. The idea of IPM is that you are taking measures at all stages of production and utilizing a variety of tools to minimize the damage that insects may pose to crop loss. The foundation of this approach relies on a pyramid of strategies to employ, with specific emphasis on pest prevention using cultural management tools. The order and size of each piece of the pyramid represent their value to sustainable pest management and level of pest intervention (Fig. 1). The goal of IPM is to provide a holistic, long-term approach to minimize crop loss and interference of beneficial insects, such as pollinators and natural enemies, that provide essential and free services on the farm.
Figure 1. Integrated pest management triangle.
Cultural approaches to management
Cultural controls are the foundation of this pyramid and lay the groundwork for the resilience of a growing system. This category includes pest prevention tactics such as tillage, removal of nearby weeds that may be harboring pest populations, proper location selection (for some insects rotating a specified distance can inhibit their travel to the crop host), timing of planting to avoid the pest on the landscape, cultivar selection, and crop sanitation or disposal of infested plants or plant parts. Many of these cultural tools can be used on all farms, but not all. For example, rotating a potato field more than 400 m from the previous year for Colorado potato beetle management may be impossible on a small farm or if a neighbor is growing potatoes nearby. In that situation, taking years off between crops and coordinating this with neighbors can help break the cycle.
Figure 2. A strawberry plant is next to a weedy patch that is hosting damaging aphids (Photo by Samantha Willden).
Weeds provide refuge or an alternative host for pests, including aphids (Fig. 2). To implement the timing of crop initiation during a season, you can use degree-day simulation models that can help predict, according to the weather in your area, pest lifecycles and when to plant to avoid peak damaging life stages. The University of Wisconsin maintains one of these models that expands into Indiana: VDIFN. Alternatively, this is something that you can begin to record and make alterations based on your local observations from year to year.
Cultivar selection for disease resistance is something that is well-published and available from many seed companies. In relation to diseases that are transmitted by insects, you can find published information that allows you to select plant cultivars that are resistant to the disease. This does not necessarily mean they won’t be infested with the insect, so direct damage from the pest is still a potential threat. In practice, insect performance on various cultivars is sometimes context-dependent and doesn’t translate from one location to the next. It is best for you to experiment with different cultivars and settle on one that you see less damage occurring on. Or ask your seed provider what they know about a particular pest and its preferences among the cultivars you may be considering. Sometimes, you can find this information in a variety of trial reports as well.
Physical management approaches
This category refers to the physical exclusion of pests to prevent them from gaining access to the crop. This option is often most available to smaller farms because of the material and labor needs. Examples include exclusion netting, low tunnels, caterpillar tunnels, high tunnels (Fig. 3), and even greenhouses. However, large-scale strawberry and melon farms sometimes use low tunnels in some locations. In addition to providing a physical barrier against pests, many of these coverings can insulate crops by capturing heat, which is particularly useful in winter and during the shoulder seasons. In some orchards and vineyards there are tree-sized mesh bags or cages to exclude particular insects or other animals from damaging the crop. For farmers who follow organic production methods, physical exclusion is one of the best strategies available for things like cucumber beetles or flea beetles.
Figure 3. High tunnels provide several benefits to crop production, including a physical barrier for pests and crop insulation (Photo by Samantha Willden).
Biological management approaches
This refers to the use of living organisms to manage a pest population. The most common method would include biological control. On a farm there are two different strategies to implement biological control that can be effective. The first is conservation biological control, which refers to creating a habitat that conserves and promotes natural enemies that are already present in the environment. This can include the installation of beetle banks, floral strips, or companion plants (Fig. 4) to provide supplemental habitat for natural enemies, which forage on a variety of different insect pests or consume plant pollen or nectar. One common natural enemy that can be recruited includes syrphid flies (Fig. 5). The second strategy is augmentative biological control, which introduces commercially purchased natural enemies, such as lacewings (Fig. 6), ladybeetles, minute pirate bugs (Fig. 7) and other, into the habitat. One goal of augmentative is to flood the environment with high numbers of natural enemies without the intention of establishing them long-term. This method follows a similar mindset to spraying a pesticide for temporary pest knockdown. Alternatively, you may try to inoculate the habitat with lower numbers of a natural enemy that will establish, reproduce, and maintain control. This method is much more difficult, and there are research gaps regarding the most effective strategies for achieving this in open-field production.
Figure 4. Companion planting with sweet alyssum (Photo by Samantha Willden).
Figure 5. Syrphid fly larvae are common naturally occurring predators of soft-bodied pests, such as aphids, thrips, and spider mites. They are common targets for conservation biological control and are not commercially available in the United States (Photo by Samantha Willden).
Figure 6. Egg card containing commercially reared green lacewing eggs. Cards were deployed on tomatoes for aphid management (Photo by Samantha Willden).
Figure 7. Minute pirate bugs are a commonly used augmentative biological control agent for thrips and aphid management. They are widely available commercially in the United States (Photo by Samantha Willden).
Another category of biological control includes the use of biopesticides to suppress pests. Many biological organisms have been formulated as pesticide sprays to apply to food crops. Some, but not all, of these products are OMRI-approved. They include active ingredients that are naturally derived and, in many cases, include living organisms such as viruses, insect-killing nematodes (Fig. 8), bacteria, and fungi. Their efficacy can be species-specific (i.e., viruses typically only infect one species of host pest) and rely on a suitable environment to effectively establish and infect the host insect (i.e., many are temperature and humidity-dependent and sensitive to direct sunlight).
Figure 8. Entomopathogenic nematodes are used as a product for below-ground insect pest management (Photo by Samantha Willden).
Chemical management strategies
Chemical management rests at the top of the IPM pyramid and should be used sparingly and as a last resort when cultural, physical, and biological control efforts fail. The risks of relying too heavily on chemical pest control are a risk of pesticide resistance and disruption of natural enemies and pollinators that can lead to larger problems on the farm down the line. There are a variety of different chemicals originating from biological or synthetic sources. Some carry the Organic production-approved label, while many do not. The most important thing to know is that despite the origin of the killing compound in the chemical spray, resistance can develop. To help alleviate this, we have created the Insecticide Resistance Action Committee (IRAC,) which has assigned a number corresponding to the mode of action for which the compound works to kill the insect. To reduce the development of resistance, the applicator should rotate among these modes of action. For assistance in selecting the proper chemical for your pest situation, consult the Midwest Vegetable Production Guide. Always follow the label on the product. The label is the law.