How can I manage pests while minimizing harmful effects on my health and the environment?

A Question of the Week
Garden

For farmers and gardeners alike, Integrated Pest Management (IPM) is an approach that uses chemical pesticides as a last resort, combining a variety of approaches to prevent and control pests and diseases. IPM doesn’t preclude the use of chemicals, nor does it require the use of organic products, but rather it’s an approach that results in less chemical use and successful management of pest challenges in the home, yard and garden.

The most important step in using an IPM approach is identifying and understanding the pest or pests that are causing harm in your home, yard or garden.

Identifying Pests

Sometimes identifying pests means identifying a physical sample. For example, you see a swarm of insects feeding on your garden plants. However, sometimes you need to identify a pest through symptoms, which might occur from a pest that is active at night.

If you can capture or photograph a suspected pest, you can go about identifying it in a couple ways.

  1. Narrow your list of suspects by researching common pests of the plant or plants that your suspected pest is attacking. For example, if you see that an insect is damaging your cucumbers, you can narrow down your list of suspects by researching common pests of cucumbers. We recommend limiting your search to research-based sources, which can include reputable books and resources from Cooperative Extension services like UNH Cooperative Extension. This website will narrow your search to resources provided by your Cooperative Extension Service.

If you can’t identify your pest yourself, there are some possible reasons why.

    1. The suspected pest you’ve captured or photographed isn’t the source of the damage. Most insects found in your garden and landscape are not harmful, and the presence of an insect on your plants doesn’t mean it is causing damage.
    2. The suspected pest you’ve captured or photographed may not be a common pest of the plant it is damaging, which means it may not be listed on resources you’re looking at.
    3. The suspected pest you’ve captured or photographed may be at an immature developmental stage, making identification more challenging.
  1. Submit a sample or photograph of the suspected pest to UNH Cooperative Extension for identification. Home gardeners can email a photo to the UNH Cooperative Extension Infoline, using these best practices to increase the likelihood of a positive identification. You can also submit a physical sample to our Arthropod ID Lab, which may be a better option for situations where a high quality photograph isn’t possible. There is a fee of $10 per sample for the Arthropod ID Lab.

If you are only able to observe symptoms of pest damage, you can go about identifying the pest in a couple ways.

  1. Research pest issues associated with the plant or plants that your suspected pest is attacking. For example, if you notice damage to your peach fruits, you can research common pests and diseases of peach trees. By looking at pictures and descriptions of pest and disease symptoms, keeping in mind factors such as the time of year and typical timing of damage from various pests and diseases, you may be able to successfully identify the cause of the observed damage.
  2. Submit a sample or photograph of the damaged plant material to UNH Cooperative Extension. Home gardeners can email a photo to the UNH Cooperative Extension Infoline, using these best practices to increase the likelihood of a positive identification. You can also submit a physical plant sample to our Plant Diagnostic Lab, which may be a better option for suspected fungal diseases, situations where a high quality photograph isn’t possible, or if the Infoline isn’t able to make a positive identification. There is a fee of $20 per sample for the Plant Diagnostic Lab.

Not only is it important to identify pests, but identifying insects that do no harm, and beneficial insects, is important as well. One reason to identify beneficial insects is that they may be helping control pests or pollinate your garden and landscape plants, and by knowing about beneficial insects you can take steps to protect and support their populations.

Once you’ve successfully identified the pest or disease that’s causing damage in your home, yard or garden, the next step in IPM is to understand the life cycle of the pest. Here are a few examples of why understanding the life cycle of the pest could be helpful.

  1. If you’ve identified grubs as a cause of damage to your lawn, understanding the life cycle of grubs is critical for timing of any control measures. Even the right control practices, if not done in accordance with the life cycle of the grubs, could fail to control the pest.
  2. If you’ve identified a caterpillar pest, understanding its life cycle, including its maturity and how long the species remains in the caterpillar stage before pupating, is critical to inform what control measures to use.
  3. If a disease is impacting your tomato plants, understanding the life cycle of the disease – whether it overwinters in the soil or is airborne, for instance – will inform how you control and prevent the disease.

UNH Cooperative Extension, and other Cooperative Extension services, have fact sheets on most pests and diseases that you might expect to encounter in your home, yard and garden. These fact sheets address the biology and life cycle of the pest and are an excellent place to focus your research once you’ve identified the pest.

Using IPM to Control Pests

Mechanical and Physical Controls

Excluding a pest is often the best approach to controlling it. Once you’ve learned about the pest’s biology and life cycle, you may find that exclusion is a good option.

For example, if you are growing squash and have had issues with the squash vine borer in previous years, you can take steps to exclude the flying moths from laying eggs on your plants by utilizing spun-bonded row covers or netting. In fact, this is one pest where you can use UNH Cooperative Extension pest alert data to inform when you set up your row covers or netting.

Another example of when exclusion would be helpful is when managing nuisance wildlife, such as woodchucks or deer. Using the appropriate fencing is often the most effective management technique in these situations.

Aside from exclusion, another important physical control can be hand picking. With garden pest issues, such as an insect feeding on a few shrubs in your landscape, hand picking is often a practical and effective technique. While a commercial grower may not be able to handpick pests off hundreds or thousands of plants, a gardener may be able to handpick a pest from a couple rose bushes rather than using a pesticide. One common pest that we almost always recommend handpicking as the best control measure is for the Japanese beetle. Another example is the tobacco and tomato hornworm.

Cultural Controls

Cultural controls are best practices for growing healthy plants that often prevent or reduce the impact and prevalence of harmful pests. A few examples of common cultural practices that gardeners can use as part of an IPM approach are:

  • Selecting the right plants for the planting location in the garden or landscape, considering the plant’s water, soil type and sun exposure needs.
  • Selecting disease resistant varieties whenever possible, such as for fruit trees, ornamental plants and vegetables like tomatoes that are often afflicted with fungal diseases.
  • Using good watering practices, such as watering plants early in the morning at the ground level while minimizing splash up of soil and wetting the leaves.
  • Vigilantly removing dead and diseased plant material and keeping diseased plant material out of your compost pile. Cleaning up your garden beds in the fall, as well as throughout the growing season, is a critical IPM practice. This is often referred to as sanitation. Keep your tools and equipment clean by disinfecting them after use on diseased plants.
  • Testing your soil and following the recommendations to ensure your plants are receiving adequate nutrients and minerals. Healthy plants are more resilient and tolerant of pests and diseases than stressed plants.
  • Rotating your annual crops, ensuring that crops you are rotating into a bed aren’t susceptible to the same pests that were active in that same bed the previous year.
  • Manage weeds and minimize habitat for pests. By learning about the biology and life cycle of pests, you can identify areas where they overwinter and hide and reduce or eliminate those habitats.
  • Prune your trees and shrubs as appropriate to ensure adequate air flow and sunlight penetration, which can help reduce fungal disease infection.

These are just some of the many cultural practices that can make a significant difference in a successful IPM program for your home, yard and garden.

Biological Controls

The most important biological control home gardeners can do is encouraging and promoting beneficial insects, which include pollinators and insects that prey on pests. Above all, the best way to encourage beneficials is with diverse plantings, which includes ensuring you have plants that are blooming and fruiting throughout the growing season. Discreet use of pesticides is also important, because indiscriminate use of pesticides will reduce populations of beneficial insects in addition to the pest you are trying to target.

There are some biological pesticides available to homeowners, such as Bacillus thuringiensis (Bt), nematodes and spinosad. These biopesticides be active against certain pests, and most of these products are very targeted. Be aware most of these products do not kill immediately and are often most effective against the young larval stages of pests.

Chemical Controls

Pesticides, which include insecticides, herbicides and fungicides, should be used as a last resort and be chosen and applied with care. Use the most selective product available, avoiding broad spectrum products whenever possible.

Before using a pesticide, follow this basic checklist:

  1. Ensure you have correctly identified the pest.
  2. Check in with your threshold for damage. Do you need to eliminate the pest, or can you tolerate some level of damage? It’s important to be realistic, and you shouldn’t expect plants or vegetables to look perfect, like you might expect at the grocery store. Some pest damage can usually be tolerated.
  3. Ensure that the pest is in the correct stage for treatment. For example, if you are controlling magnolia scale, you might need to ensure that the scale is in the crawler stage to use a product successfully.
  4. Ensure you have selected a product that is registered for use on the plant and pest. For example, if the Colorado potato beetle is damaging your eggplant, the label of a suitable product would need to specify that it is registered for use on eggplants and for controlling the Colorado potato beetle.
  5. Read the product label. The label is the law and you must use pesticides in ways fully consistent with the label. Pay attention to precautionary statements, including how to protect yourself while using the product. Also note hazard statements, such as effects on wildlife and the environment. The directions for use will tell you the pests the product will control, what the product is intended to protect, the proper equipment to be used, how much to use and how often to apply, mixing directions, computability with other products, where and when the product should be applied, and the preharvest interval.
  6. Ensure you have a plan for storage and disposal of the product, in accordance with the label directions.
  7. Check environmental conditions, such as if it is windy, if rain is in the forecast, and if it’s exceptionally hot. Depending on the product and how it’s being applied, these environmental conditions could impact successful and safe application of your product.
  8. Evaluate and monitor the application site after using pesticides. Record what worked and what didn’t, adjusting accordingly.

If you have any questions about the use of pesticides in your home, yard and garden, contact the UNH Extension Infoline for guidance.

Even if you incorporate pesticides into your IPM practices, the use of physical, cultural and biological practices remains indispensable.


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Got questions? The Ask UNH Extension Infoline offers practical help finding answers for your home, yard, and garden questions. Call toll free at 1-877-398-4769, Monday to Friday, 9 a.m. to 2 p.m., or e-mail us at answers@unh.edu.