University of Kentucky College of , ENT-69 Food and Environment Cooperative Extension Service Integrated Pest Management Kentucky Master Gardener Manual Chapter 9

By Gail Gredler, former extension agent, Yamhill County, Oregon State University. Adapted for Kentucky by Patricia L. Lucas, extension integrated pest management specialist, Department of Entomology, University of Kentucky. Photos by Ric Bessin and Blake Newton, Department of Entomology, University of Kentucky.

ll gardeners have pest problems from time to time, and pest In this chapter: management can be a real challenge. Insects, diseases, weeds, slugs, and other animals can cause significant plant What is IPM?...... 127 Adamage. How you react to a pest problem depends on the value of Developing an IPM Program...... 128 the affected , the cost of treatment, the toxicity of available controls, and your personal philosophy. Cultural Methods...... 129 Many gardeners are concerned about the use of . Some Physical Methods...... 131 pesticides, if not used, stored, and disposed of carefully, can harm Biological Methods...... 135 the applicator, the environment, children, pets, and other nontarget organisms. Chemical Methods...... 139 You can address these concerns by implementing integrated pest For More Information...... 141 management practices in your . Thoughtful, well‑researched pest management choices will reward you, the environment, and the beneficial organisms with which you share your garden. What is IPM? Integrated pest management (IPM) is a strategy to prevent and suppress pests with minimum impact on human health, the envi‑ ronment, and nontarget organisms. —Steve Dreistadt, University of California

IPM has been used in commercial agriculture since the 1970s. Many of the principles that guide in making pest manage‑ ment decisions can be used by gardeners as well. IPM is a systematic approach to pest management that focuses first on preventing problems. It involves monitoring pest popula‑ tions, identifying pests, and choosing a combination of tactics to keep pest populations at an acceptable level. Pest management tactics may include cultural, mechanical, biological, and chemical methods. IPM stresses trying the least toxic methods first.

Cooperative Extension Service | Agriculture and Natural Resources | Family and Consumer Sciences | 4-H Youth Development | Community and Economic Development 128 • Integrated Pest Management Chapter 9

Developing an IPM Program Identifying Pests Most plant problems in home Monitoring are due to nonbiological factors such as Don’t wait for trouble to happen. poor growing conditions, temperature Regularly check your plants for signs and extremes, poor water management, soil symptoms of pest damage. During the compaction, or mechanical injury. When height of the growing season, check each you discover a plant problem, the first step plant two or three times per week. is to rule out these factors as the cause. Because many pests prefer sheltered If you conclude that you do have a pest sites, inspect the undersides of leaves problem, the next step is to find the pest and the inner parts of plant canopies. itself or typical signs and symptoms associ‑ Occasionally, check your plants at night ated with it. Correctly identifying a pest is with a flashlight. half the battle and can require some detec‑ Look closely at any plant that is miss‑ tive work. Many organisms do no damage, ing leaves, flowers, or fruit. Also look for and many others are beneficial. Make sure plants with color, texture, or size that looks the organism you identify actually is the one unusual. Compare each plant to others of doing the damage and not just one that hap‑ the same variety and to what it looked like pens to be present. in previous years during the same season. Many resource materials can help with Take notes on what you find. Record the pest identification. If you are stumped or date, damage present, and any pests seen. need to confirm an identification, ask an In subsequent years, your records will help experienced extension master gardener or you know when to look for signs and symp‑ county extension agent for assistance. toms of specific pests and how to recognize Don’t stop with correct identification. them when you see them. Learn all you can about the pest’s life cycle. Several tools will help you do a good job Try to determine at which point the pest is of monitoring. A 6–15X hand lens can be most susceptible to control measures. For very useful when checking for spider mites, example, an insect may be soft-bodied as a fungal fruiting bodies, and other small signs larva and hard-bodied as an adult. Typically, and symptoms. Plastic bags and glass jars soft-bodied insects are controlled more eas‑ are good for collecting pests and examples ily than hard-bodied ones. Also, it usually is of damage. A flashlight is another useful easier to control relatively immobile insects tool, as many pests are active at night. than those that fly. Thus, timing of controls Some insect pests can be dislodged by may be critical. laying a sheet below the infested plant and Similar principles apply to weeds. For gently shaking the plant. Other insects example, seedlings often are controlled can be monitored with traps. See “Physical more easily than mature weeds. Methods” later in this chapter for more information. Chapter 9 Integrated Pest Management • 129

Establishing Your Tolerance Level Cultural Methods Consider how much damage both Some cultural pest management meth‑ you and your plants can tolerate. A small ods prevent pest problems by keeping amount of plant damage is not inherently plants healthy and growing vigorously. undesirable. For a pest’s natural enemies to Others directly address specific pest survive, it must have a pest population on problems. which to feed. If you are a meticulous gardener, you may not be willing to tolerate much dam‑ Choosing Resistant or age. If so, you need to be aggressive in Tolerant Varieties monitoring and managing pests. Less Your selection of plants strongly influ‑ meticulous gardeners are willing to accept ences what pests you are likely to encounter. more damage. The amount of time, energy, When possible, choose plants that are not and money you are willing to invest in pest prone to serious pest problems. management also will influence the level of Most garden plants are available in more damage you will tolerate. than one variety (cultivar). Some varieties Also consider how much damage each are genetically resistant to attack by certain plant can tolerate. Some food plants can diseases and insects. A plant’s level of resis‑ tolerate quite a bit of defoliation without tance is determined by its physical charac‑ exhibiting decreased yields. Likewise, teristics or chemical composition. Other significant defoliation can occur on some varieties can tolerate a lot of damage with‑ ornamental plants without causing per‑ out a significant decrease in appearance or manent damage. Seedlings are less able to yield. These plants are termed tolerant. withstand pest damage than are mature Some of the most common garden prob‑ plants. Use references and experience to lems, such as black spot on roses, scab on help you determine whether a plant is likely apples, anthracnose on dogwoods, and root to withstand pest damage. weevils on rhododendrons, can be avoided by choosing resistant or tolerant varieties. Developing a Pest Some plants have natural resistance or Management Strategy tolerance. In other cases, plant breeders produce resistant or tolerant plants. Thus, After you have identified a pest and new varieties are introduced continually. decided its damage is unacceptable, you Consult seed and plant catalogs, nurseries, need to develop a pest management strat‑ and your county extension office for sug‑ egy. Your strategy may involve the use of gested varieties. more than one tactic. The rest of this chap‑ ter focuses on tactics for managing insects, diseases, slugs, and snails. Putting the Right Plant in the Right Place Evaluating Results Place plants in an environment where Evaluation is an important and often they will grow well. A few plants will grow overlooked part of a pest management in a wide variety of environments, but most program. Did your strategy work? Was the require fairly specific conditions. Consider pest controlled to your satisfaction? You can neighboring plants; soil pH, moisture, and answer these questions by continuing to drainage; and exposure to sun and wind monitor your plants carefully. Again, record when choosing plants for a specific site. your observations for future reference. 130 • Integrated Pest Management Chapter 9

Many gardeners make the mistake of Adding organic matter to soil helps going to a nursery and choosing the most retain water and nutrients in sandy soil beautiful plant regardless of whether they and improves drainage in clayey soil. It also have an appropriate place for it. It is much encourages beneficial soil microorganisms. wiser to analyze the conditions of your These microbes break down organic mat‑ planting space and then select a plant that ter and make nutrients available to plants. will thrive in those conditions. There also is evidence that microbes and fatty acids in can suppress certain Starting with Healthy Transplants soilborne diseases. Buy only plants that are free of pests, wounds, and symptoms of insect or disease Keeping Your Garden Clean problems. Choose healthy-looking plants Proper sanitation can prevent many pest with good color. Container plants should be problems. Many pests live and breed in in a sterilized potting medium and should debris, so promptly remove any veg‑ be well rooted but not pot-bound. etation that isn’t serving a purpose. Remove Give plants a good start by planting them all unused fruit and nuts immediately. properly. Planting techniques for specific Remove pest-infested leaves and fruit types of plants are discussed in other chap‑ as soon as you see them. If an annual plant ters of this handbook. Space plants accord‑ is badly infested with insects or disease, ing to mature size. Crowded plants invite remove the entire plant. Prune out diseased pests. and dead branches of woody plants. Add disease- or insect-infested plant parts to Keeping Plants Healthy your compost pile only if you are hot com‑ posting. Otherwise, destroy them. Plants growing well are less likely to suf‑ Keep your garden as weed free as pos‑ fer a pest attack than are stressed plants and sible during the growing season. Weeds are better able to withstand pest damage if harbor insects and diseases in addition an infestation does occur. to competing with garden plants. They Know your plants’ nutrient needs and provide food, shelter, and a place to breed fertilize accordingly. An underfertilized for insects, slugs, and snails. Cutworms, ear‑ plant is stressed and vulnerable to pest wigs, flea beetles, lygus bugs, thrips, , attack, and an overfertilized plant may have and leafhoppers are common pests associ‑ excess succulent growth that can invite ated with weedy areas. disease and insect pests. Some landscape Eliminate hiding places for slugs and plants require very little, if any, fertilization. snails by removing boards, plastic sheet‑ Others, especially those that flower or fruit ing, unused plant pots, and plant debris heavily, may require several fertilizations from your garden. Regularly check for pests per year. under containers and in other hiding spots. Provide adequate but not excessive Clean your gardening tools, especially irrigation. Drought-stressed plants are tools, regularly. Use rubbing more susceptible to pest attack. Plants in alcohol, a disinfectant such as Lysol, or a excessively wet soil suffer from a lack of soil solution of 1 part bleach to 9 parts water. If oxygen and are vulnerable to attack by root- you are pruning diseased plants, make sure disease organisms that prefer wet soil. to disinfect tools between each plant. Soil pH also is important to plant health. Most plants do well in slightly acid soil (pH of 6.0 to 7.0). Acid‑loving plants such as azaleas, blueberries, and rhododendrons prefer a pH of 4.5 to 6.0. Chapter 9 Integrated Pest Management • 131

Rotating Annual Plants All of these interactions can and do occur. Unfortunately, relatively little When the same plants are grown in research has been done on companion the same soil each year, insect and disease planting, and many claims of positive populations build up. Many pests overwin‑ results have not been substantiated. ter in the soil and move to a specific type of Experiment in your garden and take host plant in the spring. By growing differ‑ careful notes. Over several seasons, you ent plants in different places each year, you may notice that certain plants have fewer deprive pests of their hosts. This technique pests when grown close to another specific works best for annual flowers and vegeta‑ type of plant. Keep in mind that even if a bles, since they are replanted each year. particular combination of plants reduces Since insects and diseases often infest pest problems, competition between the members of the same plant family, it is best plants may decrease crop yields. to rotate to a member of a different fam‑ involves mixing plants to ily (Table 1). A more extensive list of plant break up pure stands of a single crop. The families is in Chapter 6, “Plant Diseases.” physical separation of individual plants of A similar principle holds true for peren‑ one type by those of another may inter‑ nials. If you remove a perennial plant rupt the movement of insects and diseases. because of a soilborne insect or disease, However, although this patchwork planting plant something from a different family in approach may discourage pests that feed its place. on a narrow range of plants, it may encour‑ age generalist feeders such as cutworms, Table 1. Plant families for rotations. cucumber beetles, and aphids. Plant family* Representative members Apiaceae Carrot, celery, fennel, parsley, parsnip Physical Methods Asteraceae Chicory, endive, globe artichoke, lettuce Brassicaceae Bok choy, broccoli, Brussels sprout, cabbage, cauli- Physically blocking, removing, or trap‑ flower, collard, kale, kohlrabi, mustard, radish, rutabaga, ping pests can be very successful and causes turnip little disruption of your garden’s ecosystem. Chenopodiaceae Beet, spinach, Swiss chard Cucurbitaceae Cucumber, melon, pumpkin, squash Fabaceae Bean, pea, vetch Hand-Picking Liliaceae (Alliums) Chive, garlic, leek, onion, shallot Hand-picking large, clearly visible, or Solanaceae Eggplant, pepper, potato, tomatillo, tomato slow‑moving insects, slugs, and snails can *A more complete list of families and representative genera is in Chapter 6, “Plant reduce pest populations in small plantings. Diseases.” You can try the following hand-picking practices: • Pick off large beetles and caterpillars. (Make sure they really are pests!) Crush and Intercropping the insects or drop them into a container of soapy or oily water. Companion planting is growing two or • Rub off scale insects with your fingernail more specific types of plants together in the or a plastic scrub pad. hope that the combination will discourage • Shake insects such as asparagus beetles disease and insect pests. For example: onto a sheet and destroy them. • One plant can act as a “trap” and draw • Remove and destroy entire leaves pests away from the other. infested with leaf miners. • One plant may produce a repellent or • Lift spittlebugs out of their foam and toxic substance that discourages or destroy them. harms pests. • One plant may provide habitat for natu‑ ral enemies of the other plant’s pests. 132 • Integrated Pest Management Chapter 9

These techniques require careful obser‑ Row covers vation of affected plants, including the Row covers are sheets of synthetic mate‑ undersides of leaves. You must hand-pick rial that cover an entire row of plants or most species every few days to keep damage individual plants. Originally designed to at an acceptable level. extend the gardening season by retaining The best time to collect most insects is heat, they also keep insect pests away from early morning, when temperatures are cool plants. They can exclude migrating pests and insects are sluggish. Use a flashlight at such as root maggots, cucumber beetles, night to find slugs, snails, and other pests flea beetles, whiteflies, aphids, leafminers, that feed at night and hide during the day. and cabbage loopers. Row covers should allow air, water, and Spraying with Water light to reach plants. Apply them before A forceful stream of water can dislodge, seedlings emerge or when setting out injure, or drown small, soft‑bodied pests. transplants. This technique is useful for aphids, mites, Floating row covers are among the easi‑ lacebugs, mealybugs, and spittlebugs. est to use. Simply place them over plants, The water must hit the pests directly, so leaving enough slack to allow for plant you may need to spray the undersides of growth. Bury the edges to make certain leaves. Spray early in the day so plants have insects can’t enter. a chance to dry before evening. You may Check under covers frequently for need to spray every few days to remove intruders. Pests that do get in are protected returning pests. from their natural enemies and can do a lot of damage. Remove covers if it gets too hot underneath, if plants require insect pol‑ Pruning lination, or when plants are large enough to If pests are concentrated at one or two withstand some insect damage. sites on a plant, you may be able to prune them out. For example, aphids often cluster Plant cages on new growth. Tent caterpillars and fall You can make protective cages by attach‑ webworms gather in webs; prune out and ing screen or row cover material to wood, burn the entire web, if practical. Remove wire, or PVC-pipe frames. These cages cane borers in raspberries and roses by should last several seasons. pruning the affected canes while the insects Another way to make a cage is to shape are inside. Cankers on landscape and fruit a piece of screen into a cone and staple the trees sometimes can be removed by prun‑ edges together. Place cones over seedlings ing as well. until plants are large enough to tolerate In addition, regular pruning makes a some damage. plant less dense, which allows beneficial Always sink cages about 1 inch deep in insects to locate their prey more easily. the ground. It also improves air circulation, which Plant collars decreases the incidence of foliar diseases. Before pruning for , evaluate Collars can protect seedlings from whether potential pest damage is greater cutworm damage. Use toilet paper tubes, or than potential pruning damage. cut the ends out of tin cans or paper cups to form a tube. Place a tube over each seedling. Using Barriers Bury the edge of the tube 1 inch deep. Row covers, plant cages, plant collars, sticky barriers, metal barriers, and diatoma‑ ceous earth physically shield plants from insect, slug, and snail damage. Chapter 9 Integrated Pest Management • 133

To protect against root maggots, cut tar Vacuuming paper into disks at least 3 inches in diam‑ eter, cut a slit in the disk for a plant stem, Commercial growers have used this and slip the disk around a seedling so the tar technique successfully for many years. It paper lays on the soil surface. Flies are then works best with insects such as whiteflies unable to lay eggs next to the seedling. and spider mites that congregate in groups and do not scatter when disturbed. Use a Sticky barriers hand‑held, wet/dry vacuum to suck these Sticky materials can be used to catch pests from infested plants. For best results, climbing insects as they make their way up vacuum early in the morning, when pests a plant’s stem. This technique is effective are lethargic. Seal the vacuum contents against adult root weevils on ornamentals, in a bag, freeze overnight if possible, and ants on fruit trees, and climbing caterpillars discard. and beetles. Rather than applying the sticky adhesive Mulching directly to the plant, first wrap the stem Many disease organisms (pathogens) or trunk with a 3- to 4-inch-wide band of overwinter in the soil. When the weather paper, plastic, or cotton. Then apply the warms in the spring, they become infec‑ adhesive to the wrap. Add more adhesive tious and can be splashed or blown onto as soon as the trap is covered with insects, plants by rain or wind. A layer of new dust, or debris. mulch laid down in early spring can protect Metal barriers emerging plant tissue from these organisms. For example, this technique can protect You can edge a garden bed, container, or roses from the pathogens that cause black group of plants with strips of copper (or a spot. combination of copper and zinc) to repel slugs and snails. When these pests try to cross a copper strip, they are repelled by a Rototilling chemical reaction that occurs between the Although rarely used strictly for pest copper and their slime. The strip should be control, tilling does help control certain at least 6 inches wide to keep large slugs and pests such as slugs, symphylans, and cut‑ snails from “hopping the fence.” worms. Tilling kills some, buries some so deeply they can’t crawl back to the sur‑ Diatomaceous earth face, and exposes others to predators and Another barrier to insects is diatoma‑ extreme weather. ceous earth, which is made of the fossilized remains of diatoms (a type of tiny algae). Trapping This material has microscopic, sharp edges that cut an insect’s cuticle (outer “skin”) and Many pests can be attracted to and cause dehydration and death. It also can be caught by traps. Some traps kill large num‑ used for slugs and snails. bers of pests. Others are used as monitoring The main drawback to diatomaceous devices; by knowing when a pest is present, earth is that it is not effective after it you can time control measures effectively. becomes wet. You can use it as a dust on Traps are unlikely to completely rid your plants during dry weather if you do not use garden of a pest species. They simply are a overhead irrigation. Always wear a dust way to reduce pest populations. They eas‑ mask when using diatomaceous earth. ily can be used in conjunction with other techniques. 134 • Integrated Pest Management Chapter 9

Colored sticky traps Codling moth traps Some insects are attracted to certain A band of corrugated cardboard around colors. Take advantage of this attraction by a tree trunk will capture codling moth placing colored, adhesive-coated traps near larvae in the fall as they travel down the a pest infestation. The insects are attracted tree looking for a place to spend the winter by the color and then caught in the adhe‑ under loose bark or fallen leaves. Wrap a sive. These traps are used to monitor for 2-inch-wide band of large‑core corrugated pests and identify pest infestations. Yellow cardboard around the trunk at least 18 traps attract fruit flies, whitefly adults, inches above ground. Place the band on the winged aphids, psyllids, fungus gnats, apple smoothest bark possible so larvae can’t get maggots and some species of thrips. Blue under the band. The corrugations should be traps attract some species of thrips. Yellow vertical (parallel to the tree trunk). When sticky traps should be used to determine if larvae move down the tree, they will enter apple maggots are present. If present, red and remain in the corrugations. Replace the spheres, which resemble apples, can be band weekly. coated with adhesive and used to capture apple maggots. However, apple maggots are Slug traps not present in all areas of Kentucky. Gardeners have used slug traps for years. Sticky traps are available in most gar‑ These traps consist of a covered container den centers, or you can make your own. filled with bait. You can buy slug traps at To make a flat sticky trap, paint a piece of garden centers, but recycled pint plastic 1⁄4-inch plywood or other flat surface the containers with an entrance hole cut in the appropriate color. For sphere traps, use a side work just as well. Fill traps with beer commercial trap or paint a croquet or ten‑ (non-alcoholic works better than alcoholic nis ball. Be sure to use waterproof paint. types) or commercial bait to the level of Cover the painted trap with adhesive. the entrance hole and place them on the You can use a commercial adhesive, motor ground. Remove dead slugs every couple of oil, petroleum jelly, or a 50-50 mixture of days. Renew the bait as needed. petroleum jelly and dish soap. All these Pheromone traps adhesives can be cleaned off with vegetable oil. Some traps are baited with pheromone (a Set the trap on a pole near infested plants chemical that usually attracts a single spe‑ or hang it from a branch of an infested cies) and coated with adhesive to trap pests. plant. Place the trap as close to the infes‑ Often the pheromone is a synthetic version tation as possible. If you want to catch a of the chemical used by females to attract maximum number of insects, check the males. Consequently, many pheromone trap every few days and renew the adhesive traps capture only male insects. as needed. If you are using the trap to moni‑ Pheromone traps are used extensively tor a pest’s emergence or peak flight, check in commercial agriculture to help farm‑ the trap as often as necessary to adequately ers detect the presence of a pest species in interpret changes in the pest population. order to time other control measures, which is probably their best use in gardens as well. Rolled newspapers You are unlikely to capture enough insects Moist, rolled newspapers can trap ear‑ to prevent mating and egg laying. wigs, sowbugs, and pillbugs. In the evening, If you have never had a particular pest, lay the traps on the soil surface where pests do not use the pheromone trap designed for are numerous. The next morning, tap the it; you might end up attracting the pest to pests out of the traps into a dish of soapy your yard. water. Chapter 9 Integrated Pest Management • 135

Light traps Predatory insects eat large numbers of There are a number of light traps, also other insects. Some are predaceous as both known as “bug zappers,” on the market. adults and larvae, some are predaceous These traps are not effective in controlling only as larvae (such as the syrphid fly and pests and actually end up killing far more lacewing), and some only as adults. Many beneficial and innocuous insects than they predatory insects feed on only certain types do pests. of insects (for example, lady beetles eat mostly aphids), while others feed on a wide variety of insects. Common predaceous Biological Methods garden insects include lady beetles, pray‑ In a well‑balanced ecosystem, insect pest ing mantids, green and brown lacewings, populations are kept in check by natural ground beetles, minute pirate bugs, damsel enemies such as other insects, birds, bats, bugs, syrphid fly larvae, assassin bug, and snakes, frogs, toads, and moles. Disease spined soldier bug. See Figure 1 for exam‑ organisms often are kept under control by ples. Spiders, predaceous spider mites, and competition from other microorganisms. centipedes also are important predators in a Even weeds have natural enemies: insects garden ecosystem. and other animals. Parasitoids are insects that live on or in a You can use biological controls to help host insect, feed on the host, and usually kill keep pest numbers low. Don’t expect natu‑ it in the process. Most parasitoids are small, ral enemies to keep your garden pest-free, stingless wasps or flies that lay their eggs in however. Usually, some pests need to be or on specific host insects. The eggs hatch, present for natural enemies to survive. and the larvae feed on the hosts. These insects are not easily seen, but research shows they have an important impact on Beneficial Insects pest insect populations. Flies of the family Most insects are not pests. Only those Tachinidae, commonly called tachinid flies, that feed on desirable plants or transmit are also parasites of other insects. Like para‑ disease cause problems for gardeners. Many sitic wasps, their larvae live in or on other insects are very useful, and it is worth learn‑ insects and may help reduce pest numbers. ing to recognize them. Most good insect Tachinid flies come in a variety of shapes, references include pictures and descriptions sizes, and colors. Many have gray stripes of beneficial insects. and dark-colored bodies that make them The three types of beneficial insects are: difficult to distinguish from true houseflies , predators, and parasitoids. and flesh flies. An insect taxonomy guide Insect pollinators include several bee and and microscope are needed to accurately fly species. In home gardens, honeybees, identify tachinid flies. Compared to flesh bumblebees, mason bees, and flies and true houseflies, tachinid flies are syrphid fly adults are the most important robust and hairy. Figure 2 shows the braco‑ pollinators, but many other minor pollina‑ nid wasp and tachinid fly, typical parasitoids tors also play a part. in Kentucky. See Table 2 for examples of beneficial insects and the pests they control. 136 • Integrated Pest Management Chapter 9

Figure 1. Some beneficial predatory insects common to Kentucky.

Ground beetle larva (left) and adult Green lacewing larva (left) and adult Big-eyed bug

Lady beetle larva (left) and adult Syrphid fly larva (top) and adult Tachinid fly

Assassin bug Damsel bug Spined soldier bug Minute pirate bug Robber fly

Table 2. Examples of beneficial insects and pests controlled. Figure 2. A beneficial parasitoid insect common to Predators Pests controlled Kentucky. Big-eyed bugs Aphids, leafhoppers, lygus bugs (nymphs), spider mites Green lacewings Aphids, leafhoppers, plant bugs (immature), spider mites, thrips Hover flies (syrphid flies) Aphids Lady beetles Aphids, mealybugs, scales, spider mites Minute pirate bugs Aphids, spider mites, thrips, immature stages of many small insects Parasitoids Pests controlled Hymenoptera parasites Aphids (larvae), cutworms, loopers, omnivorous (e.g., ichneumonids, leaftiers, oriental fruit moths, tortrix moths Braconid wasp braconids, and chalcids) Tachinids Codling moths, Colorado potato beetles, corn earworms, cutworms, grasshoppers, hornworms, imported cabbage worms, plant bugs, tussock moths, others Chapter 9 Integrated Pest Management • 137

Table 3. Garden flowers that attract beneficial insects. Protecting beneficial insects Common Name Parasitoids All beneficial insects are susceptible to (Botanical Name)* Predators Attracted Attracted . Most insecticides available Apiaceae (carrot family) to home gardeners are broad‑spectrum, Angelica (Angelica archangelica) Lacewings, lady beetles — meaning they kill a wide range of insects, Anise (Pimpinella anisum) — Wasps including beneficials. If you decide to use an Blue lace (Trachymene coerulea) — Wasps , take the following measures to Caraway (Carum carvi) Bugs, hover flies (syrphid Wasps flies), lacewings protect beneficial insects: Coriander (Coriandrum sativum) Hover flies Tachinids, • Choose the least toxic wasps that will be effective. See “Chemical Dill (Anethum graveolens) Hover flies, lady beetles Wasps Methods” later in this chapter for more Lovage (Levisticum officinale) — Wasps information. White lace flower, bishop’s weed Bugs, hover flies, lady Tachinids, • Spot-spray only infested plants. (Ammi majus) beetles wasps • Do not spray plants in bloom. Yarrow (Achillea spp.) Bugs, lady beetles Wasps • Spray early in the day when many insects Asteraceae (daisy family) are less active. Blazing star, gayfeather (Liatris spp.) Bugs Wasps Chamomile (Anthemis nobilis) Lady beetles — Creating habitat for beneficial insects Coreopsis (Coreopsis spp.) Lacewings, lady beetles Wasps Invite beneficials to your yard by provid‑ Cosmos (Cosmos bipinnatus) Hover flies, lacewings, — minute pirate bugs ing them with food. Pollinators are attracted Golden marguerite (Anthemis Lady beetles Tachinids, by a wide variety of blooming plants. tinctoria) wasps Many adult predators and parasitoids Goldenrod (Solidago altissima) Bugs, lady beetles, soldier Wasps feed on nectar and pollen in addition to beetles pest insects. Most are quite small and can Marigold, signet (Tagetes tenuifolia) Minute pirate bugs Wasps reach the nectar and pollen of only small Mexican sunflower (Tithonia Hover flies, minute pirate — rotundifolia) bugs flowers. The flowers that attract them Sunflower Helianthus( annuus and Hover flies, lady beetles Wasps sometimes are referred to as insectary H. debilis) plants. Table 3 is a list of common insectary Tansy (Tanacetum vulgare) Hover flies, lady beetle Wasps plants. larvae By scattering insectary plants throughout Brassicaceae (cabbage family) your garden and landscape, you can attract Broccoli (Brassica oleracea) Hover flies Wasps beneficial insects. Or consider reserving a Candytuft (Iberis umbellata) Hover flies — garden bed or border for insectary plants. Mustards (Brassica hirta and B. Big-eyed bugs, hover flies, — Blends of insectary plant seeds are available. juncea) minute pirate bugs Sweet alyssum (Lobularia maritima) Hover flies Tachinids, Many nonflying predators such as wasps ground beetles and spiders need a place to Dipsaceae (scabiosa family) hide from their enemies. Groundcovers and Cephalaria (Cephalaria gigantea) Hover flies Wasps coarse mulches such as bark dust and straw Pincushion flower(Scabiosa Hover flies Wasps provide this habitat. caucasica) Beneficial insects also need water. If you Scabiosa (Scabiosa atropurpurea) Hover flies — do not use overhead irrigation, sprinkle Fabaceae (legume family) your plants lightly early in the morning to Alfalfa (Medicago sativa) Bees, bugs, lacewings, — provide water. lady beetles Clover (Trifolium spp.) Bees, bugs, lacewings, — lady beetles Hydrophyllaceae (waterleaf family) Fiddleneck (Phacelia tanacetifolia) Bees, bugs, hover flies — Polygonaceae (buckwheat family) Buckwheat (Eriogonum spp. and Hover flies — Fagopyrum spp.) *This list includes only some of the many plants whose pollen and nectar attract beneficial insects. 138 • Integrated Pest Management Chapter 9

Buying and releasing beneficial insects The following hreet strains of B.t. are Some insect predators and parasitoids can currently available to gardeners: be purchased. Common examples include lady • B.t. kurstaki is active against lepidopter‑ beetle adults, praying mantid egg cases, green ous larvae (butterflies and moths) such lacewing eggs, and parasitoid wasp pupae. as cabbage loopers. Do not use it on In general, releasing large numbers of plants that provide habitat for desirable beneficial insects has not proven to be an butterflies and moths. A few insects have effective method of pest control in the developed resistance to this strain. home garden, especially in the case of adult • B.t. israelensis is active against mosquito lady beetles. These insects tend to move and fungus gnat larvae, but it is not around and often end up migrating out of harmful to other aquatic organisms. the garden. Migration is less of a problem • B.t. san diego is active against Colorado with insects released as eggs (lacewings and potato beetles and elm leaf beetles. Trichogramma) or with mites. Meeting beneficials’ needs well enough Other B.t. products are in development. to keep them in your garden can be compli‑ A pest must ingest B.t. to be killed. Apply cated. All beneficials require a reliable food B.t. when young larvae are feeding, since source, and some require a very specific they eat the most and are most easily killed. food. Some beneficials also require specific Thoroughly cover all plant surfaces. Many temperature and humidity conditions. insects feed on the undersides of leaves, , which provide a con‑ so make sure to spray or dust there as well. trolled, closed environment, often provide Apply B.t. on an overcast day or late in the the best conditions for release of beneficials. day, as it breaks down in sunlight. Most for‑ A number of insects and mites are available mulations are effective for only a few days, for use against pests such as so repeat applications may be necessary. whiteflies, thrips, and spider mites. If you Parasitic nematodes try this method of control, make sure to order insects from a reliable source that can Also called entomopathogenic nema‑ provide instructions for maximum success. todes, these microscopic roundworms kill larval and pupal stages of certain soil-dwelling insects. They enter an insect Microorganisms through body openings and release a toxic Several microorganisms can be used to bacterium that kills the host insect as the keep pest populations in check. As nematodes feed and reproduce within it. research continues, more products contain‑ The host dies within a few days, releasing ing viruses, fungi, bacteria, protozoans, and thousands of additional nematodes into parasitic nematodes will become available. the soil. When applied properly and at the Bacillus thuringiensis (B.t.) correct time, parasitic nematodes can be effective in controlling white grubs and This bacterium contains a toxin that other beetle larvae, cutworms, and certain poisons some insects. When ingested by a other pests that live or hide in the soil. susceptible insect, it paralyzes the insect’s In order for nematodes to be effective, gut, causing the insect to stop feeding and soil temperature should be at least 55°F. eventually die. Thus, they may not be effective against B.t. has two important advantages over early-season pests. conventional insecticides. First, it affects The soil must be moist for nematodes to only a narrow range of insects, thus spar‑ be active. Water thoroughly before apply‑ ing most beneficials. Second, it is nontoxic ing and lightly after applying. Keep the soil to humans, plants, and other animals and moist, but not soggy, for several weeks. Do has no adverse environmental effects. B.t. not apply in direct sunlight, as ultraviolet is registered for use on all plants and can be light kills nematodes. Dusk or dawn appli‑ used up to harvest on edible plants. cations are best. Chapter 9 Integrated Pest Management • 139

Nematodes usually are sold on a sponge, Chemical Methods in a gel, or on another absorbent material. Mix them with water and apply them to Chemical methods of pest control raise the ground with a watering can or sprayer. concerns about human safety, toxicity to Products containing the nematode species nontarget organisms, runoff, leaching, Heterorhabditis bacteriophora are best for disposal problems, and possible residue on relatively sedentary pests such as beetle food . Thus, consider chemical con‑ grubs, whereas products containing the trols only if other techniques do not result nematode Steinernema carpocapsae are best in adequate pest control. Some chemical for soil-burrowing caterpillars (for example, controls can be used in concert with other cutworms). techniques. Parasitic nematodes do not adversely When choosing a chemical, always make affect humans, plants, or earthworms. certain it is labeled for the plant on which However, they may kill some soil dwelling it will be used. Choose the chemical that beneficial insects. Parasitic nematodes have meets the following criteria: a finite shelf life, so make sure to check the • Least harmful to the environment expiration date. They also have a short- • Least toxic to the applicator term effect in the soil. Several weeks after • Most specific to the pest application, nematode activity drops off • Least harmful to beneficial organisms considerably. Labels give a general idea of toxicity by Other microorganisms the use of signal words. Pesticides labeled Other beneficial microorganisms are “Caution” are the least toxic, those labeled used regularly in commercial agriculture “Warning” are more so, and those labeled and eventually will become available to “Danger–Poison” with a skull and cross‑ home gardeners. Beauveria bassiana, a bones are the most toxic. Other sources of fungus that kills aphids, thrips, and other information about pesticides include agri‑ soft‑bodied insects, is available to home cultural chemical references, IPM reference gardeners. Several products containing books, your county extension office, and microorganisms are available to prevent the National Pesticide Telecommunications plant diseases. Expect to see more in the Network. (See “For More Information.”) future. Insecticidal Soap Other Animals Sodium or potassium salts of fatty acids Certain species of birds, bats, snakes, are the active ingredient in insecticidal frogs, and toads also eat insects. Garter soap. Soap kills insects primarily by damag‑ snakes, frogs, and ducks are predators of ing their cuticle. It is useful against soft‑bod‑ slugs and are particularly welcome. ied pests such as aphids, thrips, whiteflies, You can encourage beneficial animals to spider mites, scales, leafhopper nymphs, live in your garden by meeting their habitat spittlebugs, and some caterpillars. needs. Water features (especially those with Insecticidal soap is virtually nontoxic to circulating water), plants that provide food humans and biodegrades rapidly. It may kill and cover, grassy areas, and bird feeders all predatory insect larvae that are feeding on attract these predators. pests when soap is applied. Otherwise, it is safe for most beneficials. Insecticidal soap must contact pests directly to kill them. It is effective only while still wet; there is no residual activity after it dries. It usually does not kill insect eggs, so repeat sprays often are necessary to control newly hatched pests. 140 • Integrated Pest Management Chapter 9

Soap can damage certain plants. Use it Botanical Insecticides according to label directions and do not use it on water‑stressed plants or if the weather Botanical insecticides are derived from is very hot. Another way to avoid damage plant material. Most botanicals are less is to spray plants, let the soap dry, and then damaging to the environment than syn‑ rinse it off with a spray of water. thetic insecticides because they break down There are many homemade recipes for to nontoxic compounds rapidly, usually insecticidal soap made from liquid dish‑ within a day or two of application. Thus, washing detergent. These sprays are risky there is less chance for environmental con‑ to use because different detergents have tamination or residues on food crops. different concentrations of active ingredi‑ Botanicals are not necessarily less toxic ent. If spray is too concentrated, it may to humans, however. Some, such as nicotine harm plants. It is best to use a commercial sulfate and rotenone, are more toxic than product that has been tested thoroughly on common synthetic garden insecticides. a variety of plants. Other botanicals, such as azadirachtin (neem extract), are nontoxic to humans and other nontarget organisms. Horticultural Oils Because botanicals break down so rap‑ Horticultural oils are made from petro‑ idly, it is important to time application care‑ leum products, vegetable oil, or fish oil. fully. Apply the chemical when and where it They kill pests and their eggs by suffocation. will reach the greatest number of pests. Oil sprays can control aphids, scales, white‑ flies, mealybugs, spider mites, lacebugs, Inorganic caterpillars, adelgids, and leafhoppers. They also can protect plant tissue from pathogen and Insecticides entry. Because oils kill on contact, good A number of mineral‑based compounds spray coverage is essential. are toxic to insects and plant disease Horticultural oils are not toxic to wildlife pathogens. For example, sulfur is both an or humans, although they can cause eye and insecticide and a . It protects many skin irritation. They degrade rapidly, mostly plants from foliar diseases such as powdery through evaporation. mildew, black spot, and scab. It also is used Oil sprays fall into two categories: as an insecticide against thrips and aphids dormant oils and summer oils. Dormant and is a powerful miticide. It is not toxic to oils are heavier and are used on woody humans. Do not use sulfur in conjunction plants during the dormant season to kill with horticultural oil sprays or when the overwintering pests and eggs and to protect air temperature is above 85°F. Under these against disease. Summer oils are lighter and conditions, it can cause plant damage. more refined. They can be used year‑round Copper is another broad‑spectrum because they are less likely to damage fungicide used on fruits, nuts, ornamentals, plants. Ultrafine oils are highly refined sum‑ and a few vegetables. Copper‑based fun‑ mer oils and are least likely to cause damage. gicides protect plants against a wide array To prevent plant damage when using of fungal and bacterial diseases. Copper is oils, carefully follow label directions, toxic to fish and earthworms. especially dilution rates. Do not use on water‑stressed plants or if relative humidity is high. Do not use when the air tempera‑ ture is below 40°F or above 90°F. Do not use oils on blue evergreens, because they break down these plants’ waxy coating and turn them green. Chapter 9 Integrated Pest Management • 141

Synthetic Insecticides, When considering using a chemical to control a pest, carefully evaluate the situa‑ Fungicides, and Molluscicides tion and try cultural, physical, and biologi‑ Many garden pesticides are produced cal controls first. Chapter 10, “Pesticides synthetically. Common synthetic products and Pesticide Safety,” contains a checklist of include insecticides such as carbaryl, mala‑ things to consider before you decide to use thion, and acephate; fungicides such as cap‑ a pesticide. tan, chlorothalonil, and triforine; If you determine that a chemical is such as glyphosate, 2,4‑D, and dichlobenil; necessary, spot-spray infested plants with and molluscicides such as metaldehyde. the least toxic effective chemical. Read the Toxicity and the potential for environ‑ product label carefully and follow all sug‑ mental damage from these products vary gested safety practices. widely. Evaluate each pesticide on its own merits and drawbacks. For More Information Radcliffe’s IPM World Textbook: http:// ipmworld.umn.edu/index.html Kentucky IPM: www.uky.edu//Ag/IPM/ ipm.htm 142 • Integrated Pest Management Chapter 9

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