Integrated Pest Management
When I first heard the term “Integrated Pest Management,” the word management grabbed my attention. Was it really possible to manage pests? In my garden, it seems that the pests are managing me. But seriously, pests are no laughing matter. Frankly, the sight of holes swallowing up the leaves of a beloved plant are more likely to bring on a bout of sobbing. And then, you find yourself wishing that there was something you could just spray on the plant that would solve the whole problem — without hurting your plant or the environment. Sorry to say, there’s rarely an easy and safe solution like that. But by increasing our knowledge base of insects, we gardeners can develop confidence in our ability to solve a pest problem in an effective way that does the least possible harm. That’s the basic idea of Integrated Pest Management.
By now, most of us are well aware of the harm that conventional pesticides can cause, from contamination of water supplies to the devastation of pollinators, to name just a few. These concerns led to the principles of Integrated Pest Management (IPM), which “integrates” various tactics — i.e., by combining preventive measures with biological and mechanical controls to reduce the need for chemical pesticides — and making that insecticidal spray a last resort. As the Cooperative Extension Service recently put it:
“the goal of IPM is often not to eliminate the pest population, but to “reduce” it to levels that are considered acceptable (or “below threshold levels”). Using an integrated pest management program helps promote a more balanced ecosystem.
— “An Introduction to Integrated Pest Management,” Va.Coop.Ext. Pub. ENTO-365.pdf (2020).
It’s worth noting that the principles of Integrated Pest Management (IPM) have been adapted for use with other problems, including plant diseases and weeds.
But what exactly is IPM? Here’s one of the best descriptions I’ve come across:
IPM does not mean simply switching from chemical pesticides to organic pesticides. Nor does it mean eliminating the use of all chemical pesticides completely. IPM can and may include the use of some chemical pesticides. According to the National Coalition on IPM, 1994, “IPM is a strategy that uses various combinations of pest control methods, biological, cultural, and chemical in a compatible manner to achieve satisfactory control and ensure favorable economic and environmental consequences.” IPM is not one single action, it is a process, a series of steps that must be carefully thought out ahead of time. Each step depends upon the given situation, the given pest and your given ability, both physically and financially, to accomplish all of the steps.
— Clemson Coop.Ext. Fact Sheet, IPM, Clemson.edu
If you’d like to watch a video covering the basics about IPM, just follow this link: IPM Basics with the “Bug Guy” of Maryland Coop. Extension.
What are the steps in the IPM process? Let’s say you’ve noticed a problem in your garden — perhaps a plant that looks chewed or a whole row of vegetable plants that look troubled. Most IPM adherents would say that noticing the problem early is a key step in the IPM process, so regular monitoring is a critical element. Farmers who employ IPM “scout” their rows regularly for problems, and we home gardeners need to do that, too, so we can formulate a solution before too much damage is done. Once you’ve spotted the problem, your next step is to identify the pest.
1. Identify the Pest and Learn More About It
Correctly identifying your pest is a critical first step. A mistake in identification can lead to ineffective control tactics that waste time and money and may lead to unnecessary risks to the environment or people; even worse, you could end up wiping out a beneficial insect that might have controlled your pest all by itself. I have to admit that this first step did not appeal to me, since getting up close and personal with bugs is not an activity I would ever choose. However, I experienced a feeling of victory when I correctly identified the pest that was eating my rhododendron. And I never even spotted the actual culprit! In my case, the type of damage visible on the plant was a clear pointer to the particular pest involved.
A little time on the computer reading up on the typical pests that harass your particular plant, studying photos of the damage caused, and learning about the pest’s life cycle will often enable you to make a positive ID. Be careful in your amateur sleuthing; when I turned over the leaves of my struggling plant, I came across several tiny insects, and at first I thought I’d found the culprit. However, when I came across two different types of insects on the same leaves, it occurred to me that one of them could be a beneficial — an insect which likes to eat the pest.
For help in identifying a pest, try the following resources:
- Use an online photo guide. There are several extremely helpful online photo-based identification resources that show the insect at various life stages and the type of damage they cause:
For tree and ornamental pests: https://www.pubs.ext.vt.edu/Insect Pests of Ornamentals Slide Show
For lots of photos and a clickable guide: Bug Guide.net, hosted by Iowa State University Dept. of Entomology
- Use Extension resources: For detailed information and accompanying photos on a long list of pests, check this extensive listing of pest publications from Virginia Cooperative Extension: Resources for Garden Insect Pests, Va.Coop.Ext.
- Use the Pest Management Guide: Virginia Tech produces an annual Pest Management Guide, and until I actually consulted it, I assumed it dealt only with chemical pesticides, but it is much broader than that. It contains a wealth of information about both pests and diseases, using an IPM approach to effective treatments. Pest Management Guide 2020/Va.Coop.Ext./Pub. No. 456-018/ENTO-336.pdf. For example, it contains an extensive Index to Insects and Mites by Host Plant in chapter 4.
- Get expert help. If you’re having trouble identifying your pest — and especially if there appears to be more than one pest — call on the experts. Start by contacting the Help Desk at the Extension Office, and they will refer your problem to the appropriate extension experts at Virginia Tech.
Once you’ve identified your pest, you may already have learned plenty about it — such as its biology, habitat and life cycle. That knowledge base about your pest can be used to develop management tactics to combat the pest problem. In other words, you can use what you’ve learned about your enemy to defeat it — or at least keep it at an acceptable level.
2. Choose a strategy
The Pyramid of IPM Tactics shown above is a useful guide in choosing an intervention strategy from the four main categories: cultural, physical-mechanical, biological, and chemicals. As you move from the bottom of the pyramid, the level of intervention and toxicity increases. IPM is a decision-making process, so once you’ve identified your pest, you can review the tactics available for a number of particular pests in the Pest Management Guide published each year by Virginia Tech and the Virginia Cooperative Extension. 2020 Pest Management Guide
Obviously, altering the cultural situation of a plant is not always possible after the pest problem develops, but using best cultural practices is clearly the best prevention tactic. If you’re dealing with a pest problem right now, you’ll want to start by looking at physical and mechanical strategies.
If you’re sure it’s a pest — and not a beneficial insect — handpick as many as you can. You can drop the insects and egg clusters into a coffee can or quart jar containing some water and a bit of dish detergent.
There are traps that are effective for certain pests. You’re probably familiar with the use of a dish of beer as a trap for slugs. Yellow plastic dishpans filled with soapy water can attract aphids. Whiteflies and cucumber beetles can be trapped on homemade sticky traps, using boards painted yellow and lightly coated with oil or grease. Commercial sticky traps are available, too.
Mechanical barriers can help to exclude some pests, but may not be effective if the pest population is large. Row covers and netting are two common barriers used by vegetable gardeners. Net-covered cages can be placed over young seedlings to help prevent insect, bird, and rabbit damage. Home gardeners sometimes have success with homemade barriers, such as collars made of cardboard, tin cans, or aluminum foil. Sticky barriers on the trunks of trees and woody shrubs may prevent damage from some crawling insects, and some commercial ones are available.
Kaolin clay — which is sometimes referred to as “China clay” — can be used to form a preventive film on leaves and fruit to protect plants from the Colorado potato beetle, tarnished plant bug, leafhopper, mite, thrips, flea beetle, and Japanese beetle damage. Mix 1 quart of clay with 2 gallons of water and 1 tablespoon of liquid soap in a sprayer. Continuously agitate the sprayer to prevent clumping of the clay. Reapply every one to three weeks. This barrier is preventive; it will not work if an insect pest is already established.
- Water Sprays
Spraying infested plants with a strong stream of water can dislodge and kill many spider mites, aphids, and other relatively fragile insects.
Most gardeners are familiar with some biological strategies, such as encouraging beneficial insects like parasitoid wasps and other predators. Praying mantises and lady bugs are well-known beneficials, but there are plenty more, including ground beetles, lacewings, wheel bugs, hover flies, and predatory mites. It may take some research to identify the beneficials that are an effective tactic for your particular pest.
The best overall approach is to create an environment that attracts and supports a number of naturally-occurring predators and parasitoids. In order to do this, you’ll need to put up with some pests in the yard; just think of them as food for the beneficial insects because if beneficials have no food, they move to another location. Minimize the use of pesticides that can kill beneficial insects as well as pests.
But how does one encourage beneficials? We can take a hint from farmers, who are starting to line their rows with “flowering hedgerows” of beneficial-attracting plants. Read all about it at “Improving Pest Management and Pollination with Farmscaping,” VA.Coop.Ext./pub.PDF. The number and variety of attractor-plants was quite the eye-opener, and I encourage you to take a look at the Organic IPM Field Guide, which is a photo-based downloadable PDF on the ATTRA Sustainable Agriculture website: https://attra.ncat.org/product/organic-ipm-field-guide/. You’ll need to scroll to page 3. Here are a few of the things I learned while doing my research:
- Ladybugs (both larvae and adults) are predators of aphids, mealy bugs, mites, and soft scale, as well as of the eggs of insect pests. I was surprised to read that ladybugs are attracted to members of the carrot family — fennel, dill, and Queen Anne’s lace.
- The Tachinid fly Trichopode pennipes is a parasite of squash bugs. Although parasitism rates as high as 80 percent have been reported, the fly is still unable to control squash bug populations below economically damaging levels on farms. For the home gardener, however, encouraging this beneficial can be a useful tactic, especially when combined with physical strategies like picking off the bugs or trapping them under boards.
I barely scratched the surface, though, but I’m determined to increase my knowledge base about beneficial insects. By the way, some beneficials can be purchased, but you have to know enough to choose the correct beneficial for your pest, as well as the proper time for release when the pest is present. In some cases, these releases are a short-term solution, often requiring a repeat release each season.
Other biological tactics include pathogens and beneficial nematodes, which can be tricky to manage and more often used by farmers. Read more about these methods and their limitations at NC State Extension Gardener Handbook/ IPM / Biological Management. These products are becoming more user-friendly, however, so don’t rule them out if they’re the recommended option for a serious pest problem.
- Biorationals or Biopesticides are derived from plants, so they do not present the toxicity problems of conventional synthetic chemicals. You can read more about these in a recent Garden Shed article, Biopesticides/The Garden Shed To determine if there’s a biopesticide for your particular pest, look at the charts in the Va. Tech Pest Management Guide.
- Synthetic or Conventional Pesticides Most of us gardeners want to avoid this section of the pyramid, though it may be unavoidable in some cases. But if you’ve carefully applied the IPM process in reaching this conclusion, you’ll at least feel a bit better about it.
As part of your decision-making process, do not forget to consult the Va.Tech Pest Management Guide, which I mentioned previously. Table 2.1 identifies organic methods — including biopesticides — for control of many vegetable pests. Chapter 2-6 contains charts for many vegetable pests with helpful photographs, plus the recommended cultural, mechanical, and biological controls, including beneficial insects that are their natural enemies. 2020 Pest Management Guide /pubs456/456-018/ENTO-336.pdf. For similar information about pests of ornamentals, you can consult Table 4.5 identifying “Control Measures for Major Pests and Pest Groups” which lists known biological, mechanical and cultural controls along with the recommended pesticides for insects of trees, shrubs, annuals, and perennials.
Want to follow along the steps of the IPM process with respect to one particular pest? Here you go: NC State Ext./Gardeners Handbook/ IPM / Case Study will allow you to do just that with a homeowner whose juniper tree is looking sickly and chewed.
3. Try the Strategy & Monitor the Results
After you’ve executed your chosen first strategy, monitor the pest population. Does it seem to be reduced? Are the affected plants looking better? If not, you may decide to move up the pyramid and try another strategy. A combination of strategies my be just the ticket. Or perhaps you’ll decide that you can live with the degree of damage your plant or crop is experiencing.
Using IPM means keeping the big picture in mind. Our goal as gardeners is to have a healthy landscape that works with nature and requires few inputs, and this means that it will have a variety of beneficial insects and a tolerable level of damaging pests.
“Balancing Nature Within Your Landscape,” Clemson.edu
“Integrated Pest Management,” North Carolina Extension Gardener Handbook/.ncsu.edu_IPM5179
“Insect and Related Pests of Shrubs,” https://content.ces.ncsu.edu/insect-and-related-pests-of-shrubs
Featured Photo: Rhinocapsus vanduzeei on mountain laurel by Beatriz Moisset, CC-BY-SA-4.0, wikimedia commons
A Potential Insect Pest of Azaleas, Journal American Rhododendron Society (A. G. Wheeler, Jr.
and Jon L. Herring)