Integrated Pest Management

IPM strives to minimize problems with insects, mites, weeds and diseases by assessing the needs of plants and their proper maintenance.

IPM is a four-step system of managing landscape problems by using the methods that are the least harmful to the environment. Through observation of the landscape, recognizing and assessing any problem, monitoring its effects and evaluating the amount of damage, you are able to more effectively manage the problem with minimal environmental harm. The fourth step, management of the problem, emphasizes using the least harmful management method before moving to the next level. The four management techniques or strategies are cultural, mechanical or physical, biological and chemical.

Pest insects first feast on unhealthy plants. The best management tool is to have healthy plants. Stress prevention of plants is your first line of defense in preventing pathogen infection and pest infestation. Pathogens can be difficult to manage and damaging to the plant once present. Weed infestations are best caught early and managed by proper cultural practices.

Healthy plants are:

• More resistant to attack by insects and diseases.
• More likely to recover from environmental and other stresses.
• Better able to withstand injury.

Common stresses to landscape plants:

• Air Pollution
• Chemical Injury
• Diseases
• Drainage Problems
• Improper Plant Selection
• Improper Planting (too deep)
• Improper cultural practices
• Insects and Mites
• Light Problems (sun vs shade)
• Moisture Extremes (drought/flooding)
• Nutrient Deficiency and Imbalance (overfertilization, etc.)
• Pesticide Toxicity
• Root Injury (severing roots, machinery compaction)
• Salt Applications Nearby
• Soil Compaction
• Soil pH Extremes
• Temperature Extremes (frost, heat)
• Trunk Injury (girdling, sun scald)

3 Factors necessary for the appearance of an infectious plant disease

Disturbing any of these conditions decreases the likelihood of the infection occurring.

• Virulent pathogen
• A susceptible host
• Environment conducive to development of the pathogen

Observation

Observation is the first step in an integrated pest (or other problem) management program (IPM). Frequent visual inspection of your plants and landscape is the most important step. It is much easier to manage a problem in the early stages, whether it is a weed seedling or beginning of a disease or pest infestation.

Landscape problems may be an indicator that you have a general problem in that the needs of the plant are not met.

Recognize and Assess the Problem

Identify what the problem is, what condition (frost or freeze damage, wilting by lack of water, etc) or disease pathogen or pest is causing the damage. One handy tool to use in identifying the problem is a magnifying glass. Identify the pest by the type of damage caused by pest feeding patterns or behavior or virus/ bacterial infection. Consulting an expert may be necessary in identifying the cause of the problem.

Once you know what is causing the problem, you can judge whether the potential damage justifies management. How serious is the problem? Is it in a highly visible area? Is it a cultural problem, that is, a problem caused by improper techniques or maintenance?

Evaluate and Monitor

Evaluate and monitor the situation to see if it spreads or is localized to that one plant. Continued inspection and record keeping may be needed. By keeping records of problems, if the same problem occurs from year to year, you are better able to determine the likely cause and come up with a solution.

Determine if the degree of damage being done warrants intervention. Sometimes the long-term strategy is to do nothing at all.

The factors of timing, number, stage of plant age and development, and location of plant need to be considered. Attacks on new tender leaves are more damaging than on leaves that have matured and hardened. Insects prefer the succulent new growth to hardened leaves. Low numbers of pests may be of minimal concern, depending on the pest. However, you must know your pests and plant. Small numbers of certain pests can be quite damaging. Pests on small, immature plants can be damaging, whereas they may have little effect on mature plants.

Use traps and double sided sticky tapes to determine the number of pests present. Sometimes pheromone traps (scent traps) are used to trap pests. Check the undersides of leaves, terminal buds, branches, trunk, shoots and flowers. High visibility areas may warrant attention, while plants out of the general view may not.

Manage the Problem

Managing is not meant to control or eliminate all pests and disease. Total control and/or elimination is not possible. Most of our problems are a result of lack of soil tilth or poor maintenance practices. IPM stresses the management of a problem, rather than eradication. Management techniques are implemented, from the least toxic on up, after determination is made that the condition is unacceptable.

Let’s look at the decision to weed the garden as an example. Why do you have a weed? Did the weed seed blow in from a neighbor’s or a vacant lot? We are powerless to prevent all problems. Is the mulch thick enough? Are there bare spots in the turf? Reseeding with turf grass seed may be the solution (for a lawn), leaving no space for the seed to germinate. Is the soil healthy enough to support the plant you prefer to grow in that location (cultural methods)?

If it is not acceptable to you that even a new emerged weed be present in your landscape, start looking over your options. You may decide to jump to the second level: mechanical control (sometimes referred to as physical control) and handpick the weed, cultivate the ground to uproot the weed, or cut off the weed. If the weed is bindweed, a biological method might be used, such as the bindweed mite. You may choose to use the highest level, the chemical level and spray the weed with a soil-safe 20% vinegar solution or other organic herbicide. The step of last resort is using a synthetic toxic herbicide, often with residual value, and harmful to the soil life (depending on the herbicide).

Pulling out the weed could bring up buried weed seeds. Cultivating could bring up weed seeds, as well as losing soil moisture, and perhaps destroying roots of vegetables and other ornamentals. If you decide to pull out the weed you might choose to prevent disturbed weed seeds from re-emerging by then applying corn gluten meal to that spot. There are many choices with every problem. If you don’t determine the best appropriate cultural management technique to apply to the problem, the problem will re-occur and you will be faced with jumping to the second or higher levels again in the future.

Management techniques include:

1. Cultural Practices

Choosing appropriate plants for the area, which includes disease and/or pest-resistant varieties, is the most important decision for avoiding problems in the landscape.

Diverse plantings (companion plantings), resistant varieties, crop rotation, planting in the proper season, and shifting planting times to avoid peak insect periods are cultural methods we can implement to avoid pest problems. Each genera of plants has many species within it. Choose the species or variety best adapted to our climate and soil conditions. For instance, in planting tomatoes, choose varieties with resistance to verticillium wilt, fusarium wilt, nematodes and/or tobacco mosaic virus, shown as V F N and T on the plant label.

A diversity of plants should include pollinator friendly plants to draw beneficial insects into your garden. Plant a variety of plants that pollinators can use, with a variety of flower shapes, colors, habitat, and consecutive flowering seasons. Limit sterile, pollen less hybrids that these pollinators cannot use.

Stable ecological environments have a great many plant and animal species. The more complex the diversity of life, the more numerous and varied are the interactions between and among them. This is good for your garden. "Biological diversity increases biological complexity, which increases biological stability (or balance) . . . Balance is what happens when nature is in harmony with itself." (Grissell, 2001), Balance occurs when the natural order of things is allowed to proceed without our intervention by using pesticides, for example.

The absence of diversity is one factor that makes your lawn and garden highly susceptible to attack. Monocultures are abnormal. Expanses of single or a few plants make it easier for predators (insect or otherwise) to pinpoint their next meal.

Soil preparation for organic content and drainage is the second most important principle for avoiding problems in the landscape. Healthy robust plants are the best and natural defense against pests. Amending new planting beds for organic content and drainage, aerating and adding a minimum of one inch of organic matter to existing beds yearly (medium and high feeders) is necessary. Reduce plant stress with proper watering, and soil amendments. A diverse soil life contributes to preventing pathogen infections.

Other common gardening cultural practices to prevent problems are:

• Make effective use of microclimates. Properly site plants in the landscape with attention to their requirements: water (hydro-zone your plants), light (sun/shade), wind, soil, and temperature (to minimize freeze damage and sunscald).
• Planting trees, shrubs, perennials, bulbs etc., at the proper depth.
• Use mulch.
• Keep equipment clean to prevent spreading weed seeds, bacterial, fungal and viral problems.
• Avoid injury and damage to trees, shrubs and perennials from construction, mowers, and especially weed trimmers.

2. Mechanical

Hand picking is the number one best mechanical method for weeds, some insect pests and in removing infected leaves or plant parts.

Spraying a stream or jet of water to dislodge the insects, such as aphids, is a harmless mechanical method. Inspect the plant on a regular basis; it may be necessary to jet spray 3 or four times during aphid season. Aphids feed on tender new growth. Once leaves harden, aphids cannot pierce and suck.

Using traps to capture pests (but not bug zappers). Setting out dishes of beer is a favorite method to capture slugs and snails. Creating barriers, such as with diatomaceous earth (DE), not salt. If using DE, use only in small areas of your garden; they will kill beneficials as well. Buy the type recommended as an insecticide, not for use as a pool filter. Wear a mask to prevent breathing in the dust particles, which can damage your lungs.

Row covers, fine mesh screens, cardboard and metal collars inserted at least an inch deep and up 2+ inches around certain plants are examples of some barriers that can be used.

Remove infected plant material to the trashcan; don't compost it. Clean off deposits of sap, bark, sawdust and leaves that may contain pathogens or insect eggs. Prune off infected and damaged branches and limbs.

Clean pruners and saws with isopropyl alcohol (rubbing alcohol) or a 10% bleach solution to avoid infecting at the next cut.

Solarization of the soil can be used to kill major weed infestations, insect eggs and pathogens down to an inch of soil. Till, smooth and irrigate the area to be solarized. Cover the area tightly with a clear plastic cover for at least 4 weeks during the warmest months. The temperature needs to reach at least 140ºF. Avoid tilling the soil after solarization to prevent bringing up new weed seeds or pathogens.

3. Biological

Management through biological applications mimics natural control. In a natural, harmonious environment, there is a relatively constant population of pests and pest predators. Disturbances of weather, the environment (by building or construction, that is, change in the habitat) and/or use of pesticides create imbalances of the pest and predator populations. Our area gardens have been subject to all three disturbances from time to time.

Biological management of pests usually means the introduction into the garden of the pest’s natural enemies, living organisms such as parasitoids, predators and pathogens. Most of the natural enemies used are specific to the pests; a few are generalists and attack more than one insect pest. Natural predators we’re familiar with are lady bug beetles, praying mantids, katydids, dragonflies, damselflies, wasps, beetles, lacewings, flies, mites, true bugs, earwigs, thrips and ants.

Wasps such as the Trichogramma species are parasitoids. Using sprays of BT (Bacillus thuringiensis) bacteria, which are toxic only to caterpillars, and Bacillus popillae for milky spore disease to use against Japanese beetle grubs, are two common pathogen examples. Or introduce beneficial insects that target your specific insect threat. Lady bug beetles, aphid midges, green lacewings, bindweed mites, or beneficial parasitic nematodes are predators commonly introduced.

Promote an inviting environment for your local lady beetles, praying mantids and other predators that are already in your garden. If they find their natural habitat and a food source, they may stay. A few pests are necessary as food for the predators; otherwise they will either fly off in search of richer hunting grounds, or dine on each other.

4. Chemical

The last management practice and most harmful to the environment is the use of chemicals. Chemical applications are organic or synthetic, contact or systemic. Herbicides, pesticides, fungicides, miticides are used to kill. "Cide" means "kill." Most “cides” are contact-type chemicals that are sprayed or applied on to the plant or into the air. Systemic pest controls are applied to leaves, stems or through the soil for the plants absorption into its system. One should not eat any plants, leaves flowers or vegetables that have taken in systemic insecticides. Likewise, one should not eat plants, leaves, flowers or vegetables that have been sprayed with chemicals. Be on the safe side (read the label carefully for full instructions).

Organic “cides” are made from natural substances and break down quickly. Repeat applications may need to be made. Organic pesticide examples are insecticidal soaps, horticultural oils, and botanicals such as neem oil, sabadilla, rotenone, ryania, and pyrethrum (sometimes spelled pyrethrin).

Insecticidal soaps, such as Safer, are contact controls that work on soft-bodied insects like aphids and mites by drying their outer layer. They have minimal impact on beneficial insects.

Horticultural oils, or dormant oils, are generally applied in late winter and act by smothering the insects breathing pores, killing both the active and over wintering stages. Horticultural oils are contact controls and will also kill beneficials. Horticultural oils have been developed for summer use, and are lighter oil concentrations. To avoid premature leaf drop due to burn, do not apply oils and soaps often when temperatures are above 80º; that is, more than twice within a 7 day period. As with all substances designed to kill, follow label instructions carefully.

Twenty percent vinegar solution is an organic herbicide. There are other organic herbicides on the market as well; one new product introduced to the market last year is AllDown (www.sumrset.com). Some products are available locally. If you’re not able to find them, ask for them.

Before you turn to synthetic chemicals, consider using natural pest remedies. Study up on them, there are many books available today and many naturally based products (www.invisiblegardener.com, www.dirtdoctor.com, for example). Because many people now are choosing to live healthier lifestyles in their home and garden, the “Green Industry” is emerging, offering products that claim to be ecologically, environmentally friendly, previously referred to as organic. As with anything, the possibility for fraud exists. But there are sources consumers can access to help them in making informed, earth-friendly choices.

The Organic Materials Review Institute (OMRI) is a 501(c)(3) nonprofit organization that specializes in the review of substances for use in organic production, processing, and handling. OMRI conducts materials review according to the standards established with implementation of the USDA National Organic Program (NOP) in October 2002. Brand name review is conducted as a transparent, third party review of products intended for use in certified organic production, handling, and processing. After review by OMRI staff, applications are submitted to an independent Review Panel of experts who evaluate a product’s compliance with the NOP National List. Products that have passed review are included on the OMRI Brand Name Product List. The OMRI Listed™ seal, which these products can display on labels and in advertising and promotions, assures their suitability for use in certified organic production. (www.omri.org). Consumers and gardeners alike can access their website for additional information.

Keep in mind that natural or organic remedies also kill beneficials along with the problem insects or weeds. Follow directions carefully and in recommended concentrations only. The label is the law. The users of these products are responsible for any damage, including drift damage. Use hand held spray bottles to spot treat the area to minimize toxic effect. Spray only on calm, windless days. A small, disposable sponge craft brush comes in handy in painting on “cides” (organic or synthetic) among ornamentals and even vegetables in close quarters.

Use synthetic pesticides, herbicides, miticides or fungicides as the last resort. Synthetic “cides” are made from chemical compounds not found in nature. Many have long-lasting residual effect; some have a shorter residual life. Over time, pests develop resistance to these synthetic substances and rebound even stronger. In addition, these synthetic compounds contribute or cause unintended and harmful environmental effects.

Use specific remedies for the problem in the most vulnerable stage of growth to the pest or invasive weed. Using these products require specific knowledge of the pest and/or pathogens. Some chemicals are broad spectrum; others target specific pathogens, pests or weeds. As with organic “cides”, follow directions carefully and in recommended concentrations only. The label is the law. The users of these products are responsible for any damage, including drift damage. Use hand held spray bottles to spot treat the area to minimize toxic effect. Spray only on calm, windless days. A small, disposable sponge craft brush comes in handy in painting on “cides” (organic or synthetic) among ornamentals and even vegetables in close quarters.

Beneficial insects, organisms and plants are affected adversely as well as the bad. Removing the bad insect, fungus and/or weed along with beneficials sometimes will give room for secondary problems to move in and multiply, thereby exchanging one problem for another.

Resistant insects develop as a result of an incomplete kill. For some reason, 100% eradication is never achieved. Some of the pests that remain have some resistant quality that prevents them from being killed. When these pests multiply, the chemical resistance is passed on to the young. Soon, a new pesticide resistant strain of pest is present, and without the normal predators to keep them in check.

In the rebound effect, pests usually recover quicker than the predators. Plant-feeding insects are at the bottom of the food chain and are therefore more numerous than their predators. Naturally this makes sense. It'll take many aphids to satisfy the hunger of an aphid predator, such as a lady beetle. If pesticides killed all aphids, this guaranteed meal to lady beetles would cease. But pesticides do not wipe out all aphids (or lady beetles either, although a good many of both are destroyed at the same time). The remaining aphids multiply faster than the lady beetles. Being lower on the food chain, aphids multiply faster and stronger and may even become genetically resistant. They now face fewer enemies. Using pesticides instead of using the less harmful method, such as spraying with a jet of water, has created a greater problem.

Insect interactions with other insects, both insect predators and plant predators are within the natural order of things. One feeds on the next, that feeds on the next, that feeds on the next and so on. Disruption by chemicals sets the community off balance.

References

• Ecology for Gardeners, Steven B. Carroll and Steve Salt, Timber Press, 2004.
• Insects and Gardens, In Pursuit of a Garden Ecology, Eric Grissell, Timber Press, 2001.
• IPM for Gardeners, A Guide to Integrated Pest Management, by Raymond A, Cloyd, Philip L. Nixon and Nancy R. Pataky, Timber Press, 2004.
• Master Gardener Handbook, edited by Douglas F. Welch and Samuel D. Cotner, Texas A & M Press, 1995, third edition.
• Silent Spring, Rachel Carson, Houghton Mifflin, 1962.

Angie Hanna