Garden Insect Pest Management in the Home Vegetable Garden - Auburn University


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Garden Insect Pest Management in the Home Vegetable Garden - Auburn University

  1. 1. ANR-1045Garden Alabama A&M and Auburn UniversitiesBugs Insect Pest Management in the Home Vegetable GardenQ. How can I keep “bad bugs” out of my garden?Q. How can I attract “good bugs” to my garden?Q. How can I control slugs and other soil insect pests?Q. What insect pests are common to Alabama?Q. How can I control insect pests without insecticides?
  2. 2. Alabama A&M andGardenBugs ANR-1045 Auburn Universities Insect Pest Management in the Home Vegetable GardenT he best way to manage insect pests in the home vegetable garden is to use Making Your Garden a combination of strategies, including Vegetables Less Susceptible cultural, mechanical, and biological controls. Organic gardeners rely totally on to Insect Damagenonchemical methods. Most home gardeners can In home vegetable gardens, insecticides shouldtolerate some insect damage on their vegetables; be used only as a last resort to prevent seriousconsequently, they are able to use many insect damage. Insecticides kill beneficial insects asnonchemical control strategies that can reduce, well as harmful insects. You may not even noticebut not always eliminate, insect damage. Home that these “good” insects are present, but if they aregardeners not opposed to using chemicals may use destroyed, pest insect populations can increase tochemical controls when nonchemical methods do very high numbers.not provide sufficient levels of control. You can reduce or eliminate the need for Modern pest management relies on “planning insecticides in your garden by using a varietybefore planting” rather than responding to a of techniques. The best approach to successfullypest problem after it has occurred. For example, control garden pests is to use a combinationyou can prevent many insect pest problems by of techniques.using what you know about the pest to make thevegetable planting less suitable for pest devel- Healthy Soilopment. This could mean planting early to avoid Healthy soil will produce plants better ablehigh pest numbers that occur late in the season. to resist insects and disease. Before planting your Correct identification of insect pests infesting garden, turn over the soil and add organic matterthe vegetable garden is critical so you can develop such as manure or compost to supply essentiala management plan. Equally important is recog- nutrients. Organic nutrients are released slowly,nition of beneficial insects. Your county Extension in contrast to synthetic fertilizers which provideagent can help you identify pests and develop “quick-fix” strategies for specific pest and It’s a good idea to have your garden soil testedcrop situations. to determine if soil nutrients and pH are suitable This publication provides: for growing vigorous plants. Soil testing can be • Tips on making your garden vegetables less done for a nominal fee; contact your countysusceptible to insect damage. Extension agent for more information. • General recommendations for managingsoil pests. Companion Planting • General recommendations for managing Some plants contain or give off compounds thatabove-ground pests. repel insects. Companion planting is the practice of strategically placing insect-repelling plants next to crops that will benefit from their repellent effects. For example, planting garlic among vegetables helps to deter Japanese beetles, aphids, vegetable weevils, and spider mites; basil planted near tomatoes repels tomato hornworms; and marigolds interplanted with squash or cucumber repel cucumber beetles and nematodes. Check the organic gardening section in your library or bookstore for books on companion plants. 3
  3. 3. Crop Rotation Mulch Planting different kinds of vegetables in a Mulching is the spreading of organic matterdifferent section of your garden each year will help in the garden and around plants. It is an effectivereduce pest infestation. Some insect pests overwinter method to control weeds and also serves as ain the garden soil and emerge in the spring and refuge for predatory insects like ground beetles.begin searching for food. If the plant they prefer to Mulch also helps the soil to retain moistureeat is located several yards away, the insect must and stay cool, which promotes plant vigor andmove to the source. Many will die along the way or tolerance to insect attack.fall prey to birds and other insects. Add mulch to the garden when plants are 4 to Also, many vegetables may absorb a particular 6 inches high. Grass clippings, leaves, hay, sawdust,nutrient from the soil. By rotating your vegetable wood chips, and compost make excellent mulches.crops each year, the soil in a particular section One drawback of using mulch may be increasedof the garden will have the opportunity to rest numbers of slugs that may feed on young andand regenerate. In general, avoid planting crops succulent the same plant family in the same location inconsecutive years. For example, potato, eggplant, Compostand tomato are all in the Solanaceae family, sothese crops should be rotated with vegetables in Fertile soil is the foundation of a healthyanother plant family, such as the squash or cucurbit garden. One of the most effective ways to enhancefamily, the bean or legume family, etc. soil fertility is to add compost. Compost is made by mixing organic matter and allowing it to decay through a natural process. The end product is aDiversified Planting dark, rich substance called humus which can be A common practice among home gardeners added directly to the to plant a single crop in a straight row. This The first step in composting is to build aencourages pests because it makes it easy for them holding bin or composter. Construct the bin fromto travel from one host plant to another. If different chicken wire, scrap wood, or cinder blocks. Theplants are intermingled and not planted in straight dimensions should be at least 3 × 3 × 3 feet but canrows, an insect is forced to search for a new host vary depending on your needs. Place the bin in aplant thus exposing it to predators. Diversified convenient location. Add leaves, grass clippings,planting also works well with companion planting. and household vegetable food waste. Do not add animal residues as they may attract rats andTrap Plants raccoons. Turn the pile to aerate the material. If If given a choice, some insects will opt to feed you turn the pile every month, humus will be readyon one plant type over another. For example, in about 6 months.pickleworms prefer squash to cucumber, and sometomato worms prefer dill over tomatoes. With a Beneficial Insectslittle knowledge of host preferences, you can take Not all insects are “bad bugs.” Your garden andadvantage of this by placing certain plants where surroundings contain many insects that are actuallythey can lure harmful insects away from the plants beneficial because they feed on harmful wish to protect. Once the “trap plants” have Therefore, as a gardener, you should be able tobecome infested, the target insect can be picked off identify garden insects and determine whether theyand dropped in soapy water or the entire plant can are harmful or beneficial. Many organic gardeningbe disposed of. books provide pictures of the most common beneficial and pest insects and information on howBarriers and Traps to encourage populations of beneficial insects. Barriers and traps can be employed to capture Another good reference book with pictures ofor impede movement of pests. A collar made of beneficial insects is Natural Enemies of Vegetablethick paper or cardboard which is placed around Insect Pests by Michael Hoffman and Annethe stem of a plant and pressed into the soil an Frodsham. This book may be ordered by phoneinch or so deep will prevent cutworms and other (607-255-2080) from Cornell University Resourceburrowing insects from getting into the soil around Center. Your county Extension agent can also assistyour plants. A board or thick piece of paper you with insect identification.painted yellow and coated with a sticky substance,such as Tanglefoot, will attract and interceptaphids, whiteflies, and other small flying insects. 4
  4. 4. Table 1. Attracting Beneficial InsectsName of Beneficial Insect Prey Methods to AttractLadybugs Adults and larvae eat aphids, Grow pollen and nectar plants scales, mites, and eggs of like dill, goldenrod, yarrow, some pest insects. cosmos, sweet alyssum. Spray non-crop plants with sugar water. Provide water in a pan filled with gravel during dry periods.Hover flies Larvae feed on aphids and Grow pollen and nectar plants small caterpillars. in the Umbelliferae family. Allow some broccoli to flower. Plant tall plants like sunflower so flies can hover.Robber flies Adults capture flying insects. Larvae Plant flowering plants live in soil and feed on soil pests as a nectar source. like grubs.Ground beetles Feed on snails, slugs, cutworms and Grow pollen-providing plants. Grow other caterpillars, and on potato beetle dense cover crops to provide eggs and larvae. shelter. Incorporate grass or stone walkways between garden beds.Big-eyed bugs, flower bugs Adults eat aphids, small caterpillars, Grow pollen and nectar plants mites, turf pests, thrips, and other like sweet alyssum, alfalfa, small insects. goldenrod, and cosmos.Assassin bugs Both nymphs and adults use their Grow perennials to provide needle-like stylets to suck fluids from permanent shelter plantings. and kill aphids and other small insects and their eggs. Larger wheel bugs attack large caterpillars.Lacewings (green and brown) Larvae eat aphids, scales, thrips, mites, Plant dill, sunflowers, caraway, and eggs of some pest insects. cosmos, sweet alyssum, and golden- rod flowers. Spray sugar water on non-crop plants to attract adults.Tachinid flies Larvae are parasites of squash bugs, Grow plants in the Umbelliferae cutworms, Japanese beetles, and many family and other small-flowered caterpillars. plants like sweet alyssum and spearmint.Wasp parasites Adults inject eggs inside caterpillar Grow pollen and nectar plants in(non-stinging to humans) prey; wasp larvae develop, eventually the Umbelliferae family, also mints killing the host. Some species parasitize and herbs. White clover and other insect pest eggs. legume cover crops planted adjacent to garden beds also attract parasites. Provide shelter with tall plants like sunflowers. Let some broccoli and radishes flower. A good way to attract beneficial insects into thegarden is to incorporate plants inside or adjacent Managing Soil Peststo the garden that will supply alternative sources in the Gardenof food, such as pollen and nectar, and shelterfor beneficial insects. Remember that application General Recommendationsof synthetic insecticides can destroy the natural Many soil insect pest populations reach highbalance by eliminating beneficial insects. Table 1 numbers in grass or turf, and home gardens arepresents a partial listing of methods to attract some often established in areas previously covered withof the more common beneficial insects. grass. To reduce soil insect problems, thoroughly till or spade the area well in advance of planting (30 days or more) and again just before planting. 5
  5. 5. This will bring up soil pests near the surface where Cutwormstheir chances of mortality are increased. In mostcases, tilling the soil or sod in fall and early spring Cutworms are active only at night and remainwill sufficiently control soil insects without the buried below the soil surface near food plantsneed for a soil insecticide. during the day. They emerge to feed at night and often cut seedlings or small stems, causing the If tilling is not an option, apply a broadcast soil plants to fall over.insecticide 2 weeks before planting to help controlsome soil insects like cutworms, wireworms, and • Because grasswhite grubs. Check with your local Extension and many weedsSystem office for available insecticides. are preferred hosts, remove grass and weeds in the garden,Slugs and plow the soil well in advance Slugs like to feed on young seedlings and of planting.succulent parts of plants. They leave a trail of • You can also prevent damage bymucus on the surfaces on which they crawl. Moist, placing a paper or plastic “sleeve” over thehumid environments favor slug development, and plant and pressing the bottom into the soil.slugs usually overwinter in sheltered locations Place sleeves around newly set transplants oroutdoors. They deposit their eggs in moist areas newly emerged seedlings so that 1 inch is belowand require a year or more to mature. ground and 3 inches above ground. Paper cups • Spade or till garden area in the fall and again with the bottoms removed or 4 inch high sectionsin the spring before planting of 1⁄ 2 gallon paper milk cartons are ideal. Tuna cans • Pick slugs by hand. Using a flashlight, check with the bottoms removed may also work.the garden around 10:00 p.m. for active slugs. If • Check with your local Extension Systemyou find any, pick them up with an old teaspoon. office for available insecticides.Place captured slugs in a container of salt which • Use Sevin bait after plant emergence. Applywill kill them. Continue this activity for 3 to 4 Sevin according to label directions late in thenights in a row to greatly reduce damage. afternoon so the bait will be fresh when the worms • Place stale beer in small cups or pans sunken come out to feed at the soil so the lip of the container is slightlybelow ground level. Slugs are attracted to the beer, Wirewormsfall into the container, and drown. For best results,replace the stale beer about every 3 days. Setting Wireworms are the slender, yellowishout enough containers early in the spring can brown, hard-bodied larvae of clickgreatly reduce slug populations. beetles. They can survive deep in the soil for up to 5 years and can move • Use diatomaceous earth, lime, or sawdust as up to attack seed or young plants.a barrier; replace after each rain. Several wireworm species prefer • Pesticide baits are minimally to moderately plants in the grass family and areeffective against slugs. To increase their effec- usually not a problem unlesstiveness, apply them late in the afternoon. Bait in the garden is planted into landthe fall after the first fall rains to target slugs before that previously contained grasses orthey can lay eggs. Check with your local Extension crops in the grass family.System office for available pesticide baits. • Turn over the soil in the fall, and again in the spring well in advance of planting, to help reduce wireworm populations. • Use a granular insecticide. Slug Apply granules according to label Pacific 0.5-4.0 in. directions, and work then into the soil C o a s t to a depth of 4 to 6 inches, followed Wireworm 0.4 in. by a good watering. 6
  6. 6. White Grubs Managing Above-Ground White grubs are Japanese, May, and June beetle Pests in the Gardenlarvae that are dirty white in color. The tip of theirabdomen is a blue-black color. Nonchemical methods for managing gardenThey roll into a C shape when pests that feed on the foliage and fruit of garden L a rvadisturbed. Mature grubs may 0.5-2.0 in. vegetables are presented here.reach 2 inches in length.They live in the soil and Aphidssometimes feed on • To repel aphids, anchor aluminum foil to theplant roots and tubers. soil for 1 foot around transplants. Slope soil awayAbout the only time from plant so rain water and mud do notthey are troublesome obscure reflective surface. You mayis when parts of remove foil after plants flower.the lawn or sod are • Make a water trap byturned under in the painting a small, shallow panspring for garden use. bright yellow and filling it • If you must with soapy water. Place severalplant in previ- pans in the garden and refillously grassy areas, them after each rain. Use brightprepare the garden yellow-painted (Rust-Oleumwell in advance 659 or Safety Yellow) 6- x 8-inchof planting. As sod is Lined June Beetle 0.9-1.1 in. cards or pieces of plywood as stickyturned over, raked, and traps. Anchor vertically to gardenprepared for planting, stakes and spray with Tanglefoot Pea Aphidpick up the grubs by 0.12-0.17 in. or other sticky substance. Replacehand for the best control. Tanglefoot weekly. • Check with your local Extension System • Repel aphids by sprayingoffice for available insecticides. a mixture of 2 tablespoons hot red pepper, 2 cloves garlic, 1 tablespoon liquid soap (Tide liquidMole Crickets laundry detergent, for example), and 1 quart of Mole crickets have brown, velvety bodies with water.broad front legs for digging in the soil. They have • Hand remove and destroy aphid colonies onlarge eyes and are about plant leaves.1 inch long when mature. • Use a strong spray of water from the hose toAs mole crickets tunnel knock aphids from plants.through the soil, they can • Spray plants with insecticidal soap ordisrupt the root system liquid laundry detergent mixed with water (2 to 3of vegetables. They may tablespoons per gallon). Test tender plants first toalso feed on plant root ensure they are not burned by the soap solution.and underground stem • Because aphids can transmit plant virustissue. disease, remove and destroy diseased plants to • Avoid planting the delay spread of virus to healthy in previously grassyareas. If you observe molecricket tunnels around plants,tamp the soil back down to restoresupport to the root system. • Check with your local m o l e c r i c k e tExtension System office for available 0.8-1.2 in.insecticides. 7
  7. 7. Asparagus Beetles Corn Earworm • Plant marigolds near (Tomato Fruitworm)asparagus to repel beetles. • With no controls • Destroy and bury plant applied, earwormsrefuse in the fall to remove usually damageoverwintering sites. only the tip of the Corn Earworm • Handpick and destroy ear. Cut off the 1.5 in.eggs, larvae, and adults in the damaged tipsmorning before they become and you can eat the • If possible, avoid planting other vegetables • Spray asparagus ferns near corn, a favorite food of corn earworm. Spottedwith pyrethrin or rotenone in A sp a r a g u s • Plant and harvest corn as early in the seasonlate summer so fewer beetles B e e t l e 0.25- as possible to avoid heavy infestations.will overwinter. 0.3 in. • Drop 1⁄ 4 teaspoon of mineral oil on the silks • Cut foliage off at the of each corn ear after the silks have wilted butground as soon as it begins to die back. before they begin to dry; this helps to repel moths and egg-laying.Cabbage Loopers and • Select tight-husked corn varieties for planting.Cabbageworms Tight husks inhibit worm movement into the ear. • Cover • Beginning at the flower stage, check upperplants with tomato leaves once a week for small, round, whitecheesecloth fruitworm eggs. Spray plants with Bacillus thuringi-or floating ensis weekly as long as you detect eggs.row cover to Importedprevent egg-laying. C a bb a g e w o r m Cucumber Beetles 1.25-2.0 in. • Handpick. The green • Plant nonbitter cucumber varieties; (B)worms are much easier to the bitter compound in cucumberspot on red-leaf varieties. attracts beetles. • Spray plants with Bacillus • Cover young plantsthuringiensis when worms are still small. with cheesecloth or • Remove alternate host weeds, such as wild floating row coversmustard and shepherd’s purse, from the garden. until just before bloom. • Interplant cucumber (A) • Interplant a hot pepper plant between everytwo cabbage plants. with radishes; radish seems to Striped (A) repel cucumber beetles. Tansy, a n d S p o t t e dColorado Potato Beetle marigolds, and nasturtiums also ( B ) C u c u m b e r repel beetles. Beetles • Potato beetles prefer to feed on potato, • Eliminate weeds in and 0.2-0.25 in.eggplant, and tomato. Rotate these preferred hosts around the garden; some weeds are hosts forwith other crops in alternate years. bacterial wilt disease that is spread by cucumber • Interplant nonhost crops, such as beans, with beetles.preferred host crops. • Handpick orange Flea Beetlesegg masses, reddish brownlarvae, and yellow-and- • Unless flea beetle populations are heavy,black striped adults and their feeding will not kill plants or reducedestroy. yields; control is usually unnecessary. • Place straw mulch • Flea beetles are most numerousaround plants as a barrier to in the spring; plant susceptiblebeetle colonization of plants crops like eggplant and radish laterin the spring. in the season. • Weeds bordering the garden C o l o r a d o may serve as alternate hosts; Potato Beetle removing weeds will reduce flea P o t a t o 0.4 in. beetle populations. Flea Beetle 0.05-0.08 in. 8
  8. 8. False Chinch Bugs Leafhoppers L e a f h o pp e r 0.05-0.25 in. False chinch bugs are weed-feeding insects that • Protect plantsmay build up in large numbers in arid conditions. with cheesecloth orThey migrate in huge numbers that may overwhelm other fine mesh rowany control efforts. covering. • Early-season control of cruciferous weed • Hang brighthosts may help reduce numbers. yellow (Rust-Oleum 659 • If damage from false chinch bugs reaches or Safety Yellow) 6- xunacceptable levels, treatments to field edges will 8-inch boards covered withhelp control this pest. a thin coat of Tack Trap or • False chinch bugs are easily drowned. Heavy Tanglefoot at crop level. Whenwatering or use of a strong hose spray will drown the boards are filled with insects,many. Trenches or pans of water may be put wash them and repeat.around plants during periods of insect migration. • Spray plants with insecticidal soap. • Because leafhoppers can transmit virus diseases, remove diseased plants to delay spread to healthy plants. Mexican Bean Beetles • Handpick and destroy egg masses and beetles Differential in early morning before they become active. G r a ss h o pp e r • InterplantGrasshoppers 1.5-2.0 in. nonhost crops like potatoes among • Trap grasshoppers by using a 1 quart bean plants tocontainer half filled with a 10% molasses and disrupt egg-laying.water mixture. • Use • Grasshopper populations are most damaging soybeans as ain late summer. Use a floating row cover to protect trap cover. Beanlate-season plantings. beetles prefer • Plow the garden in the fall to expose soybeans planted Mexicangrasshopper eggs to the weather and insect Bean Beetle nearby over snap 0.25-0.33 in.predators. Be sure to plow fence rows and or lima beans. L a rvagarden borders too. 0.33 in. Spider MitesJapanese Beetles • Spray plants with insecticidal soap. • Avoid planting garden near • Keep the foliage wet tolawns or in land previously deter mites, which don’t like moistcontaining lawn. conditions; however, keeping the • Purchase a Japanese beetle foliage wet can also encouragepheromone trap plant reduce beetle numbers. Locate • Cover plants withtrap at least 30 feet away from an old blanket to createcrop plants. a cool, moist • Protect plants with J a pa n e s e B e e t l e environment thatfloating row covers. 0.3-0.5 in. deters mites. • Apply milky spore • Spray plantspowder to surrounding lawn or pasture. Milky with water or insec-spore powder is generally available on the Internet. ticidal soap; then cover infested plants for 3 days and follow with a second soap spray. T w o sp o t t e d Spider M i t e 0.01-0.02 in. 9
  9. 9. Squash Bugs Weevils (Bean Weevil or • Remove and destroy Cowpea Curculio)clusters of oval, orange- • Plant resistant, thick-brown squash bug eggs. hulled southern pea • Remove and destroy varieties like AUbe orvines and unused fruit after Freeze-Green.harvest to eliminate overwin- • Plant beanstering sites. as early as • Place shingles or possible,boards near squash or and turnpumpkin plants in spring or plantsearly summer to attract squash under afterbugs; then collect and destroy harvest. Squash Bug C o wp e aadult bugs under the boards 0.7 in. • Pick shell Curculioeach morning. beans when 0.2 in. • Plant nasturtiums and marigolds near squash somewhat green;plants to deter squash bugs. then blanch before freezing; this will kill weevil eggs and larvae which are seldom seen in theSquash Vine Borers V Squash i n e B o r e r frozen beans. • Cover plants with fine 1.0 in. • Before storing, heat beans in a 175°F oven formesh cloth or row cover until an hour. Cool beans; then bag and freeze them forfemale flowers appear. Female a week to kill any weevil larvae or eggs. After this,flowers have a bulge between store beans at room temperature.flower and stem that is absentin male flowers. Whiteflies • Plant squash varieties with long vines. • Whiteflies are rarely aThese varieties of squash may continue to grow problem in outdoor gardens.despite borer damage. Make sure purchased trans- • Plant in late summer or fall to avoid heavy plants are not infested withvine borer infestations. whiteflies or other insects. • Cut open borer entry holes in the stem with a • Hang bright yellowknife; then remove the worm and pack moist earth (Rust-Oleum 659 or Safetyaround the stem. Yellow) 6- x 8-inch boards, covered with a thin coat ofTomato Hornworms mineral oil, Tack Trap, or Tanglefoot at crop level. • Handpick worms from G r e e n h o u s e • Spray plants Wplants; check plants in the h i t e f l y with insecticidal soap. 0.06 in.evening with a flashlight. • Spray Bacillus thuringiensiswhen the worms are still small. Chemical Control of • Plant dill next to tomatoes Garden Pestsas a preferred trap crop; Check with your local Extension Systemhand-pick worms off the dill. office for available insecticides and the proper • Do not destroy application rates.hornworms with small, whitecocoons attached to their body.These are parasite cocoonsfrom which small, parasiticwasps (beneficial)will emerge. • Turn the soil in Tomatothe fall to expose Hornwormhornworm pupae to 3.0-4.0 and predators. 10
  10. 10. Use this quick reference to find morepractical problem-solving tips for your home, lawn, and garden. Scan the symbol below using the code-reading app on a smart- phone or tablet equipped with a camera. Charles Ray, Extension Research Fellow, Entomology and Plant Pathology, Auburn University. Originally prepared by Geoff Zehnder, former Extension Entomologist. Use chemicals only according to the directions on the label. Follow all directions, precautions, and restric- tions that are listed. Before you apply any pesticide, check with your county Extension agent for the latest information. Trade names are used only to give specific information. The Alabama Cooperative Extension System does not endorse or guarantee any product and does not recommend one product instead of another that might be similar. For more information, contact your county Extension office. Visit or look in your telephone directory under your county’s name to find contact information. Published by the Alabama Cooperative Extension System (Alabama A&M University and Auburn University), an equal opportunity educator and employer. 12M, Reprinted Dec 2011, ANR-1045 ANR-1045 © 2011 by the Alabama Cooperative Extension System. All rights reserved.