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Chapter 21Integrated Pest

ManagementLearning Objectives1. Explain the strategies of Integrated

Pest Management (IPM)

2. Differentiate between physical and mechanical controls

3. Relate the importance of scouting to successful IPM

4. Differentiate between pesticide resistance and pest resurgence

5. Explain the ecological significance of weeds within an IPM program

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InstructorCopy

Tennessee Master Gardener Handbook 568

Each year, homeowners use nearly 100 million pounds of pesticide active ingredients. The majority of these uses

are as herbicides. About 15 percent of the total volume of material is attributed to insecticide and fungicide use. The objective of Integrated Pest Management (IPM) is NOT to elimi-nate pesticides as a management option, but to optimize pesticide use within biologically based pest management decisions that promote sound environmental stewardship.

During the past 10 years, the concept of IPM has received considerable attention by scientists, landscape managers, growers and pesticide-conscious segments of the urban market. In 1997, IPM became a federally man-dated agricultural initiative.

IPM can be generally defined as a multi-step approach to maintaining pest populations below levels that can cause objectionable plant injury- loss of flowers, fruits and general re-ductions in plant quality. In the home garden

and landscape, successful IPM begins with scouting.

Tools for IPM ScoutingTo successfully scout the landscape or garden, gardeners need the proper tools. One of the first items in the toolbox should be a small 10x to 15x-hand magnifier with a lens not less than 20 mm (0.75 in) across. The diameter of the lens should be large enough that it is comfort-able to use for extended durations. It is also important to have a pocketknife and small, zipper-lock plastic bags for collecting and preserving root or leaf tissues until they can be more thoroughly examined. A hand trowel is useful for observing the roots of plants or searching for soil-inhabiting pests. Addition-ally, landscape hedgerows, large shrubs and patches of ground covers can be sampled quickly using a sturdy canvas sweep net. A square “beat” cloth or a light-colored pan can be used to catch arthropods shaken from plant branches and foliage. Alternatively, a clipboard or field notebook with a pale surface can be used as a backdrop to count mites or thrips shaken from plant foliage. A light-colored surface is important to allow contrast with the darker colors and shadows of small and slow-moving pests. Also, where scales are a concern, a piece of double-sided sticky tape can be used to monitor crawler emergence.

Integrated Pest Management

The IPM Initiative

In 1997, President Clinton set a goal for U.S. agricultural producers. By 2000, 75% of U.S. agriculture should be produced using Integrated Pest Management strategies.

IPM Kits

Tools for the IPM scout are inexpensive and easy to find. A complete kit can be assembled for less than $50.

Figure 1. Sticky Tape


Table 1. Management Options in IPM

Type of Control Example Management Options

Biological control

Parasitic wasps, lacewing and ladybird beetle larvae, or nematodes can be released or encouraged in the landscape to moderate pest populations. Plants that produce abundant nectar and pollen can be incorporated into landscapes to attract natural enemies and alternative pollinators. Entomopathogenic, meaning arthropod killing, fungi (Beauveria bassiana) and bacteria (Bacillus thuringiensis = Bt) can be introduced to manage many pest populations before they reach damaging levels.

Chemical control

Traditional synthetic pesticides are important components of successful IPM programs. Gardeners and landscape managers should choose a pest-specific chemical, rather than broad-spectrum pesticides, and make applications to pests in susceptible life-stages. To limit pesticide resistance, rotate to a new chemical mode of action after making two or three applications.

Cultural control

Promptly dig and destroy infested plant materials and discard infected cuttings and seeds. Wear clothing colors that do not attract pests (gray and tan) when working in the garden. Visit infested plant materials last. Select and plant pest-resistant plants cultivars or species. By watering plants in the early morning and evening, diseases are limited. Plant foliage has time to dry and midday evaporation is minimized. Cyclic irrigation limits over-watering and excessive run-off. Designing a layered, architecturally complex landscape increases the resources and space for natural enemies and limits the severity of pest outbreaks. Annually, rotate plant families that tend to be susceptible to similar pests and diseases. Plant crops in succession to provide a yield for a longer growing season. This will help avoid pest pressure during stressing climate conditions. Companion planting and inter-cropping can mutually improve the productivity of two plant species. Maintain soil health and structure by maintaining and increasing soil organic matter.

Doing nothing

Natural predators, parasites and diseases cause cyclic declines in pest population outbreaks. In complex landscape habitats, where natural enemies are abundant, small pest populations seldom reach damaging levels. Highly mobile and accidental pests may emigrate before causing significant aesthetic injury to plants.

Host plant resistance Do a little homework before buying plants for the garden or landscape. Select pest- and disease-resistant plants for new plantings and to replace dead and declining plants.

Mechanical controlUse screens, barriers or bands around seedlings, beneath benches and on the stems or trunks of susceptible plants. Hoeing, tilling and mowing control many weed seedlings and subsequently reduce pest resources.

Physical control

Plastic and woven fabric mulches warm the soil, conserve water and limit weed growth in landscape and garden beds. Properly pruned plants and adequate spacing allow air to circulate and dry foliage. In turn, this limits disease pressure and promotes natural plant health.


Finally, advise gardeners to build or invest in a small aspirator. An aspirator is a miniature vacuum that enables small arthropods to be drawn into a collection vial. With an aspira-tor, the gardener can suck a small volume of air into a screened, intake tube. The opening of a second flexible tube is then held close to the insect and the vacuum pulls the insect into the vial. Once the specimen is collected, a small volume of 70 percent isopropyl (rub-bing) alcohol is added to the collection vial to preserve the specimen for subsequent identi-fication. Tell gardeners to use permanent ink to label each vial with the date, host plant and collector.

Scouting and Monitoring TechniquesGardeners spend a lot time in their gardens and landscapes. While in the garden and land-scape, it is important to teach them to observe the beneficial and pest arthropods as well as disease symptoms and signs that can indicate the beginning of a potential problem. Regular and organized scouting is the key to success-ful landscape IPM. Scouting helps gardeners

and landscape managers locate and identify pest populations before economic and aesthetic plant losses can occur.

To get started, divide the landscape or garden into logical units and draw a map of each unit. Units may represent an individual garden, a landscape bed or different sections of a yard. Units can be divided by plant type, use pattern or environmental exposure.

Scouting Tools

10x to 16x magnifying hand lens – for observing small mites, scale crawlers and signs of natural enemies.

Clipboard and notepad – for mapping infested areas and recording your ac-tions and their results.

Sheets of white paper, a white pan or a beat cloth – for catching slow-moving pests (aphids, mites, scales) that are easy to see on the light-colored background.

An aspirator (Figure 2) – for sucking smaller flighty insects into a vial, where they can be more easily observed.

A pocketknife – for scraping bark or symptoms; or if the pest is very large, use it for personal protection.

Zipper-lock bags and plastic vials – for preserving pests or storing samples until they can be properly identified. Medicine bottles or film canisters can be also be used.

A hand trowel – for observing the roots of plants or searching for soil-inhabiting pests.

Double-sided sticky tape – for moni-toring emergence of scale crawlers on small twigs and branches.

A sturdy canvas sweep-net – for sampling larger areas of turf or within a hedgerow.

Figure 2. Aspirator


Gardeners do not need to inspect every plant in the landscape, or in a group, to be confident that pests and diseases are not at economically or aesthetically damaging levels. Instead, gardeners need to be taught the “key plant” concept. This concept is easy to under-stand and it helps focus scouting efforts.

Key plants are plants that have well-estab-lished relationships with pests or diseases. For example, eastern tent caterpillars, Japanese beetles and fire blight disease challenge many crabapple cultivars and species. Azalea lace bugs are a common problem on evergreen aza-leas, particularly in sunny, exposed landscape beds. Cabbage moth caterpillars are regular pests of broccoli and other cruciferous veg-etables and greens.

Because key plants have well-established relationships with pests or diseases, these

plants should be emphasized in landscape and garden IPM planning. Teach gardeners that when placing key plants in the landscape or garden, the most resistant plant cultivars or species within a group should be selected. Replacement plants and newly designed land-scapes will need less maintenance if pest- and disease- resistant plants are selected.

Most pest populations develop in patchy distributions, rather than evenly, in landscapes and gardens. Therefore, at regular intervals along a hedgerow, a single plant should be in-spected for signs and symptoms of pest or dis-ease presence. Make sure gardeners know that it is okay to be biased about selecting which plants to inspect. Yellow (chlorotic), wilted and damaged foliage are often indicators of disease or arthropod pest activity.

Additionally, the stems and trunks of shrubs and trees should be examined for sunk-en lesions, oozing sap, torn bark and sawdust. Leaf margins should be observed for notches, holes, discoloration or leaf spots. About 10 leaves should be randomly selected from differ-ent heights and quadrants on the plant. Areas along the main veins and broad leaf under surface should be inspected for spider mites,

Table 2. Key Plants in Eastern U.S. Landscapes with Pest and Disease Associations

Woody Landscape Plants Frequently Observed Pest(s) or Disease(s)

Azaleas Azalea lace bug, southern red mite

Boxwood Boxwood leaf miner, boxwood psyllid, boxwood mite

Camellia Tea scale

Cotoneaster and pyracantha Hawthorn lace bug

Crape myrtle Aphid, Japanese beetle, powdery mildew

Dogwood Dogwood borer, powdery mildew, anthracnose

Euonymus Euonymus scale, crown gall, powdery mildew

Holly Cottony camellia scale, holly leaf miners, southern red mite

Juniper Bagworm, spruce spider mite

Leyland cypress Bagworm, cankers

Oak Caterpillars, leaf and twig galls

Pine Bark beetles, pine sawflies, needle rust, cankers

Privet Whiteflies, sooty mold, rust mites, white peach scale

Rhododendron Stem borer, azalea & rhododendron lace bugs, rhododendron borer, phytohthora

Red-tip photinia Leaf spots and shot holes

River birch Lace bug, spiny witch-hazel leaf gall aphid, yellow-necked caterpillar, dusky birch sawfly

Rose Sawflies, aphids, black spot, powdery mildew

Tuliptree Tuliptree aphid, tuliptree scale

Tips on Scouting

Scouts do not need to inspect every plant in the landscape, or in a group, to be confident that pests and diseases are not at economically or aesthetically damaging levels.


eggs, aphids and cast skins of other pests. On larger shrubs and trees, examine three to five, 10 cm (4-inch) long, terminal stem sections per plant. Dense shrub centers where popula-tions of protected pests first develop should not be ignored.

If pests are encountered, a greater number of plant parts, or plants in a group of similar plants, should be inspected to get a better estimate of pest population size. It is a good idea to use a colored flag or ribbon to mark the outbreak location so it can be found again when making spot treatments.

In general, most landscape and garden beds should be scouted at weekly or bi-weekly intervals. Because seedlings are more suscep-tible than mature plants to root rots, cutworms and rodents, they should be scouted more frequently. With practice, it will take less than five minutes to scan the upper and lower leaf surfaces of new and old foliage, flowers, leaf axils, bark on the main trunk and stems, and the roots of a plant showing evidence of pests or disease. A half-acre landscape can be scouted in about 45 minutes.

Scouting Pests and Diseases in TurfScouting turf is no more difficult than scout-ing landscape plantings and garden beds. To scout turf, teach clients to scan for patches of discolored turf, thinning grass, spongy areas or notable disturbances from foraging birds and mammals. Next, teach them to look closer for skeletonized leaves, clipped blades, webbing or signs of feeding, such as frass or excre-ment. Mobile insects in thatch and soil can be flushed from turf with a mild soap solution. This is done by dissolving 2 to 4 tablespoons of liquid dishwashing detergent in about 2 gal-lons of water. The solution is then poured over the turf surface, covering about a 2-foot by 2-foot square (4 square feet). After about 5 to 10 minutes, sod webworms, cutworms, army-

Steps to Sound IPM

1. Scout for pests and diseases – closely observe plant stems, leaves, bark and roots for signs and symp-toms of arthropod activity and plant diseases.

2. Identify the pest or disease – use the library, Internet, picture guides and contact Master Gardener peers or your local Extension agent to confirm that the pest or disease is harmful to your plants. Determine if the pest is still present.

3. Decide which management strate-gies will be most effective.

4. Implement your management plan – Take action in time to achieve con-trol and target the most susceptible life stages of the pest or disease.

5. Record your management action and its result – What did you do? When did you do it? If you used a pesticide, which chemical and mode of action did you use and at which rate?

6. Observe the result of your manage-ment action. Which factors may have played a role in the success or failure of your effort? What will you do differently, or do again, next time you encounter the pest?

Coffee Can

Figure 3. Turf Floatation Scouting Tool

Plant Inspection

Scouts do not need to inspect every plant in the landscape, or in a group, to be confident that pests and diseases are not at economically or aesthetically damaging levels. It is okay to be biased about selecting which plants to inspect.


worms and billbugs will move into the open, where they can be collected and counted.

A one-gallon coffee can with the ends cut off also works well as a reservoir to float mo-bile arthropods from turf. The edge of the can should be pushed into the turf about an inch deep. The can should be kept full of water, replacing the volume absorbed by the soil, for about five minutes. Chinch bugs, beneficial ground beetles and other arthropods will float to the surface, where they can be counted.

When less mobile pests are feeding and active, grass sections become loosely rooted and can be easily pulled free. To examine for these pests, a flat-bladed spade should be used to dig up about a square foot of turf. Then the grass roots can be examined as well as about a 3-inch deep soil zone for the pests or damage caused by the pests.

Sticky Traps and Pheromone LuresBands of sticky glue, such as Pestik® and Tanglefoot® adhesives, keep highly mobile pests off greenhouse benches and restrict pest movement on trees. Sticky traps colored yellow attract whiteflies, aphids, thrips and flies. Blue traps attract thrips. These traps are commer-cially available. Yellow is the best choice for overall pest detection. Sticky cards are most effective for monitoring pest populations in greenhouse and interior gardens. In the landscape, sticky cards quickly become clogged with dirt and dust and indiscriminately trap pest and beneficial arthropods.

Pheromone lures are another effective tool for monitoring pest populations of difficult-to-observe pests. Clearwing moth borers are some of the most problematic pests in the landscape. The moths are strong fliers as adults. Larvae feed beneath the bark and in the stems of many different host plants. At best, these be-haviors make direct field observations difficult. To find one another in nature, these moths rely on volatile pheromones produced within their bodies and emitted as a social cue. Pheromone cues are most frequently used to find reproduc-tive mates. Chemists have synthesized many of these compounds into lures or baits that at-tract pests to traps. Because pheromones work across distances that can exceed one mile, traps are used to detect the emergence and activ-ity of pests within a season. Male moths that orient to the airborne reproductive signals are usually trapped first. Scouts can monitor these traps and make preventive trunk treatments to susceptible host plants when clearwing moths are active in the landscape.

Pheromone Traps or Lures

Pheromones are organic molecules that arthropods use to signal other members of their species (i.e., for reproduction). These pheromones can be used to at-tract certain species to a trapping device, allowing beneficial and non-threatening insects to remain safe. Traps may also be used to count pests to determine if treat-ment is needed.

Figure 4. Squash Vine Borer

Figure 5. Pheromone Trap and Stand


Management StrategiesIt is essential to teach gardeners to identify the organisms that are causing plant injury before initiating a management action. Sometimes, pest and disease problems can be readily identified using pictures and descriptions in garden magazines, lawn and garden mainte-nance books, and the Internet. In other cases, plant symptoms are less obvious. Tell clients that samples of plants with their symptoms can be taken to a landscape professional or garden center, a Master Gardener peer or sent

to your county Extension agent for accurate identification.

Once a pest problem has been identified, teach gardeners to use their knowledge of what they learned about the size and location of pest populations, the developmental pattern of the pest and pest behavior to develop a management strategy that will limit additional population growth and plant damage. Man-agement recommendations can be based on prior experience with the pest and expectations of plant injury.

To control the pest problem, an informed gardener has several options to choose from, including cultural, physical, mechanical, biological and chemical controls, as well as in-corporating host-plant resistance. In addition, the grower may elect to do nothing. Natural enemies and plant vigor can out-compete many pest population cycles.

Cultural Control PracticesIn gardens and landscapes, sanitation is con-sistently the most neglected proactive approach to limit pest introduction and population outbreaks. Dead and dying plants should be removed and destroyed. Compost piles should not include slow-dying, drought-stressed and infested plants. These “Garden Typhoid Marys” accelerate pest development and at-tract pest opportunists. As the resources in the compost pile fade, these pests leave the pile and move into the garden and the landscape.

Inappropriate plant selection and use are perhaps second for creating potential pest and

Table 3. Some Common Beneficial Insects

Insects Description Pest(s) Controlled

Ground Beetles Large, shiny, dark brown beetles Caterpillars, armyworms and cutworms

Ladybugs Small, round, colorful beetles; blue-yellow striped larva

Aphids, mites, scale and many insect eggs

Predaceous stink bugs Medical shield shape Feed on many insects

Ambush bugs Large, dark bug with long, narrow head Feed on whatever they catch

Tachnid flies Drab small fly Parasitize many insect larvae

Lacewings Stalked egg, 1-inch long with lacy wings

Aphids, mites, scale insects and many insect eggs.

Praying mantids 3-inches long insect with triangular head Many insects

Predatory Mites Very small, 8 legs, not a true insects Spider mites

Nutritional Chlorosis, Disease Yel-lowing and Spider Mite Injury

Figure 6.


disease problems. Teach gardeners to take care to choose the “right plant” for the “right place” in the yard or garden. Also, teach them to pay attention to sun and shade exposures in the planting bed and to test the soil for pH and electrical conductivity. These can affect nutrient availability and fertility. Finally, they need to: observe the planting location during and after moderate to heavy rainfall, handle the root ball with appropriate care and irrigate after planting.

Several cultural practices help minimize plant stress and disease pressure, too. Teach gardeners to be selective when selecting plants. They should only accept pest- and disease-free plants for the garden. To insure this is done, tell them to courteously inspect leaves, stems and roots closely, before getting to the cash register. They should inspect only the outside edges of root balls and then carefully replace the undisturbed roots and media back in their containers. Hoses should be kept clean by using a hook to suspend hose nozzles off the ground or greenhouse floor when not being used. Tools and containers should be washed and sanitized in a 9:1 solution of water and household bleach and soil-less potting media should be kept away from soil.

Too often, weeds are overlooked in IPM planning. Yet, weeds provide food and hiding places for pest arthropods. Weeds support fungal, bacterial and viral diseases that spread to garden and ornamental plants. Weeds also directly compete with ornamental and garden plants for water, light and nutrient resources. True, many weeds and grasses supply pollen and nectar to arthropods’ natural enemies and refuges for both predatory and prey insects. But, many ornamental and marginally orna-mental plants can perform the same function. In general, landscape managers and gardeners should not tolerate the competitive and aes-thetic losses attributed to weed populations.

Mechanical and Physical ControlsMechanical control strategies rely on labor, materials or machinery to directly exclude pests and diseases from plants. Nets, hardware, cloth screens, lightweight spun fabrics and wo-ven fabrics can be used to keep birds, rodents and pests away from seedlings and sensitive crops. Aluminum strips can be used to keep squirrels and raccoons from climbing trees.

Sterilization

Quick. Cheap. Effective. A 9:1 solution of water and household bleach sterilizes garden tools, pots and pruners.

IPM and Weeds

Weeds are often overlooked when de-signing an IPM plan. Yet, weeds provide food and hiding places for pest arthro-pods. Weeds also support fungal, bacte-rial and viral diseases that spread to gar-den and ornamental plants.

Garden Additions that Will Attract Beneficial Arthropods

Parasitic wasps and predatory arthro-pods frequently visit ornamental and marginally ornamental plants when they are flowering. Often, these are plants that provide pollen and nectar resources to sustain natural enemies when only a few prey are available. Some of the plants most heavily visited by natural enemies are listed below and can be designed into reduced-maintenance garden and landscape borders.

▪ Yarrow (Achillea sp.) ▪ Bugleweed (Ajuga reptans) ▪ Queen Anne’s Lace (Daucus carota) ▪ Joe-Pye Weeds (Eupatorium sp.) ▪ Mint (Mentha sp.) ▪ Bee Balm (Monarda sp.) ▪ Parsley (Petroselinum crispum) ▪ Sedum (Sedum sp.) ▪ Goldenrods (Solidago sp.) ▪ Betony (Stachys officinalis) ▪ Veronica (Veronica spicata)


Copper strips exclude snails and slugs from garden beds. Burlap bands are wrapped around tree trunks that shelter highly mobile tent caterpillars and gypsy moth larvae. Bands are visited regularly and pest larvae are submerged in soapy water. Weeds can be pulled by hand or burned with specially designed propane torches.

By contrast, physical controls rely on envi-ronmental manipulations that alter tempera-ture, light or moisture in the growing environ-ment. In turn, pest populations and diseases are affected indirectly. Newspaper, plastic and bark mulch and soil solarization are common examples of physical controls that moderate soil temperature and moisture levels in the garden and landscape. Soil solarization, as mentioned in Chapter 19, Weeds, is the pro-cess of killing pests by covering the soil with clear, plastic mulch. This practice can increase soil temperatures to over 120 degrees F, which can destroy certain plant pathogens in the up-per 2 to 3 inches of soil.

Additionally, shade structures and vine-covered trellises limit midday sun exposure and alter the environment below. Proper irrigation timing, in the morning and early evening, and the irrigation method, the use of drip irrigation and “soaker” hoses versus overhead irrigation, also influence temperature and humidity around the plants.

Biological Control OrganismsIn a balanced ecological system, predators and parasites are efficient foragers for prey arthro-pods. These beneficial arthropods can be con-served, encouraged or released into landscape and garden beds. Architecturally complex landscapes, which gain diversity by mixing overstory trees and shrubs with perennials, groundcovers and turf, contain more beneficial arthropods than simple plantings. Many effec-tive natural enemies are mass-reared for sale.

In the landscape and garden, pest arthro-pods are also subject to natural mortality from bacteria, such as Bacillus thuringiensis (Bt); fungi, such as Beauveria bassiana; and viruses, such as gypsy moth and tent caterpillar NPVs (nuclear polyhedrus virus). These “entomo-pathogens” are also valuable components in landscape IPM.

Once established, the survival of biologi-cal control agents is dependent on successfully integrating them with other management strategies. Many arthropod natural enemies must be supplied with alternative pollen or nectar resources to survive when preferred food resources, the pests, decline. Garden and landscape borders can be designed to include several ornamental and marginally ornamental plants that are heavily visited by beneficial arthropods. Long-residual, systemic and broad-spectrum insecticides and miticides should be avoided before and after releasing natural enemies. Fungicidal sprays are toxic to entomopathogenic fungi, like Beauveria bassiana.

Host Plant Resistance and Susceptible Sentinel PlantsNot every cultivar within a species group, nor every species within a genus, is equally susceptible to arthropod pests or disease. While this is true even for key plants, pest and disease resistance in plants can be attributed to many factors. Resistance in certain apple and crabapple cultivars to Japanese beetles is attributed to the production of elevated levels of defense chemistries, which inhibit feeding activity. Plant cells under attack by patho-gens can die rapidly, effectively walling-in diseased cells. Physical differences, like dense trichomes (leaf hairs) on some buddleia and azaleas, increase pest resistance of these plants. Thus, it is a good idea to tell gardeners to take advantage of differences in plant susceptibility when designing IPM programs. They should select pest- and disease-resistant plants for new gardens, or to replace dead or dying susceptible specimens.

Another good strategy for an IPM program is to use susceptible plants as “sentinels” for early activity of target pests. Garden beans (Phaseolus sp.) and roses (Rosa sp.) can moni-tor spider mite populations. Tomatoes and lantana can be indicators of whiteflies and aphid outbreaks can be detected on chrysan-themums. In a small greenhouse, grow seed-ling rye (Secale sp.) or wheat (Triticum sp.) in small containers adjacent to ornamental plants to detect fungus gnat activity.

Gardeners need to bear in mind that pest populations quickly build to plant-threatening levels on untended sentinel and trap plants.


Therefore it is important to regularly scout plants and treat, or remove and destroy, ef-fected plants once pests are discovered.

Chemical Control PhilosophyIn an IPM program, chemical sprays are rarely used. This is partially because complete eradi-cation is difficult, even in controlled laboratory tests. In fact, efforts to completely eliminate pest populations inadvertently result in pest populations resistant to chemical controls. In essence, if the only survivors of pesticide treatment are those that are unaffected by the chemical compounds, their offspring are more likely to be pesticide-tolerant. However, this is not to say that chemical pesticides are an unac-ceptable and integral part of successful IPM. Instead, chemical pesticides should be consid-ered as one option among several management alternatives.

Within an IPM framework, choose a pesticide after considering the expected ability to control the pest, the action of the pesticide on predatory and parasitic natural enemies and other non-target organisms, and the mode of action of the pesticide’s active chemical con-stituents. Pesticides should be applied during the most susceptible life stages of the target arthropod or disease. In short, identifying the pest and understanding pest biology optimize the effectiveness of a pesticide.

When a pesticide is selected as the best management option, emphasis is placed on making spot treatments to centralized pest populations, rather than relying on calendar-based and cover sprays. Re-treatment intervals are timed to catch pests that emerge from pesticide-resistant life stages, like eggs and pupae. Finally, the most efficient pesticide use

is accomplished by continuing to monitor pest populations after management actions have been taken.

Use of Oils and Soaps for Pest Management

Oils kill insects and mites by suffoca-tion or membrane disruption. They are derived from petroleum or hydrocarbon chains from plants. Summer or horticul-tural oils are highly refined and can be used on foliage at a 0.5-2.0 percent rate. Dormant oils are less refined and can be used on winter-dormant plants at a 2-4 percent rate. Citrus oil containing d-Lim-onene is usually combined with soaps. Horticultural oils can be phytotoxic to some plants and will take the blue blush off of Colorado blue spruce. If experience in using horticultural oil on a particular cultivar is lacking, test spray a branch and evaluate for chemical burn or phytotox-icity before spraying whole plants.

Insecticidal soaps consist of six to 10 carbon fatty acid chains joined togeth-er by potassium or sodium ions. They can disrupt the cell membranes of soft-bodied insects and mites such as aphids, soft scales, caterpillars, spider mites, beetle larvae and mealybugs. Both oils and soaps must contact the pest when applied to be effective, so good spray coverage is essential. Since there is very little residual insecticidal activity, oils and soaps should be safe for beneficial insects that immigrate to the plant af-ter spray application. Some predaceous insects such as lady beetles have some tolerance to being sprayed with soaps and oils.

Cultivar Susceptibility

Not every cultivar within a species group, nor every species with-in a genus, is equally susceptible to pests or diseases.

Pesticide Usage

Each year, homeowners use nearly 100 million pounds of pesti-cide active ingredients in their homes, gardens and landscapes.


Pesticide Resistance, Chemical Mode of Action and Pest ResurgenceIn general, pests that develop rapidly and have multiple generations within a season, like spider mites, aphids and thrips, are more likely to develop pesticide resistance. True pesti-cide resistance develops when either genetic mutations or physiological shifts occur. These changes help pests detoxify chemical active ingredients or avoid their modes of action.

A pesticide’s mode of action generally describes which insect physiological process or functional metabolic pathway is disrupted by chemical activity – in other words, how a pes-ticide stops the insect’s internal engines. Mode of action is often related to the chemical class that categorizes a pesticide’s active ingredi-ent. For example, Sevin® is a carbamate-class insecticide that disrupts the nervous system by allowing continuous axon excitation when arthropod pests contact or ingest the active ingredient carbaryl.

Resistance is more likely to occur when the same pesticide or mode of action is applied

repeatedly to control pests. Pesticide resistance can be limited by rotating chemicals with dif-ferent modes of action once two or three con-secutive treatments have been applied. Alter-natively, groups of plants can be left untreated to allow susceptible pest populations to survive and interbreed with resistant populations.

Pest resurgence can be confused with pes-ticide resistance. Pest resurgence occurs when a broad-spectrum insecticide is used to control a pest, but also kills beneficial arthropods. When the natural enemies of the pest are eliminated, pests that survive treatment or that re-colonize the crop develop without pressure from parasites and predators. As a result, sub-sequent pest populations may be larger than the initial pest population.

What Is Phytotoxicity?Plants are susceptible to phytotoxicity, or dam-age from pesticide volatization, drift and direct contact with pesticides. Seedlings are more sensitive to pesticides than parent plants. Her-baceous plants are generally more susceptible than woody plants. Exposure to direct sunlight and temperatures in excess of 86 degrees F (30 degrees C) can increase the severity of plant phytotoxic response. Phytotoxic responses are also influenced by factors including plant stress, soil temperature, pH, rate of the treat-ment solution and repeated exposure to the chemicals.

Common symptoms of phytotoxicity include loss of protective waxes on leaves and needles- particularly among conifers treated with horticultural oils and insecticidal soaps- yellowing of leaves (chlorosis), premature fall coloration, spot necrosis on foliage and flowers, leaf curl, leaf drop and plant death

Assessing and Recording Management ActionsTo be complete, an IPM program must include an evaluation of the management strategies that were chosen. After implementing a tactic, it is important to re-evaluate and record the results. Did the action keep the plant looking healthy? Did eggs or pupae of the pest survive to re-colonize the plants, or did they immi-grate from untreated plants? Was the strategy time- and cost-effective?

Figure 7. Thrips


Descriptions should be thorough and the final assessment should include important conditions that might affect results. These conditions include items such as weather, new plant/pest introductions or new equipment. Initially, these factors may not seem impor-tant, but often influence the success or failure of pest and disease management actions.

The Value of Good Record-KeepingKeeping thorough and accurate IPM and scouting records is essential for the success of an IPM program. Perhaps the most important early objective of scouting records and maps is discovering the location of pest and disease “hot spots” in the garden or landscape. Hot spots are problem areas that, more or less regularly, contribute to seasonal population outbreaks. Hot spots can be found in sunken zones or in shaded corners, in raised portions of the landscape, and adjacent to buildings or reflective windows. Once identified, hot spots can be monitored regularly to limit the severity of pest outbreaks. In our modern era, good records can also limit homeowner or gardener liability in nuisance-based civil lawsuits. Regardless, if records are well kept, they will provide an easy method of tracking the type, rate and volume of pesticides applied and the success of the management options.

SummaryIPM is a multi-faceted approach to control best populations to manageable levels. With the increasing restrictions on pesticide usage, it is more important then ever to teach gardeners the different strategies of IPM. This chap-ter has taught how to scout for pests and the strategies involved with controlling them. This chapter also focused how to assess and record management actions.

Terms To KnowArthropodsBiologicalCompanion plantingCrop rotationDriftHost plant resistanceHot spotsIntercroppingKey plants

Mechanical controlMode of actionMonitoring/scoutingNatural enemyPest resurgencePesticide resistancePheromonesPhysical controlPhytotoxicitySentinel plantsSuccession plantingVolatilization

Test Your Knowledge1. True or false? Integrated Pest Manage-

ment (IPM) relies primarily on organic control strategies and natural enemies to limit pest populations below aesthetically damaging levels.

2. What are seven general classifications of management options that, together, yield successful IPM?

3. What is the most important component of successful IPM?

4. What important step is taken after a pest is found but before management action is taken?

5. When is pest resurgence usually ob-served in the landscape or garden?

ResourcesForms for submission of weed and plant

samples can be downloaded at:soilplantandpest.utk.edu

UT Extension Publications(Adopting Integrated Pest Management, PB1603)utextension.tennessee.edu

IPM Institute of North America, Inc.ipminstitute.org/school

Northwest Coalition for Alternatives for Pesticidespesticide.org

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