Pest ManagementBACKYARD

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Insects damage plants in severalways.The most visible damage ischewed plant leaves and flowers.Many pests are visible and can bereadily identified, including theJapanese beetle, Colorado potatobeetle, and numerous species ofcaterpillars such as tent caterpillarsand tomato hornworms. Other chew-ing insects, however, such as cut-worms (which are caterpillars) comeout at night to eat, and burrow intothe soil during the day.These aremuch harder to identify but shouldbe considered if young plants seemto disappear overnight or are foundcut off at ground level.

Sucking insects are extremely com-mon and can be very damaging.These insects insert their mouthparts into the plant tissues and suckout the plant juices.They also maycarry diseases that they spread fromplant to plant as they move aboutthe yard.You may suspect that theseinsects are present if you notice mis-shapen plant leaves or flower petals.Often the younger leaves will appearcurled or puckered. Flowers develop-ing from the buds may only partiallydevelop. Look on the underside ofthe leaves as that is where manyspecies tend to gather. Commonsucking insects include leafhoppers,aphids, mealy bugs, thrips and mites.

Other insects cause damage by bor-ing into stems, fruits, and leaves.They may disrupt the plant’s abilityto transport water.They also createopportunities for disease organismsto attack the plants.You may suspectthe presence of boring insects if yousee small accumulations of sawdust-like material on plant stems or fruits.Common examples of boring insectsinclude squash vine borers and cornborers.

DiseasesPlant disease identification isextremely difficult. In some cases,

only laboratory analysis can conclu-sively identify diseases. Diseaseorganisms injure plants in severalways. Some attack leaf surfaces andlimit the plant’s ability to carry onphotosynthesis. Other organisms pro-duce substances that clog plant tis-sues that transport water and nutri-ents. Other disease organisms pro-duce toxins that kill the plant orreplace plant tissue with their own.

Symptoms associated with plant dis-eases may include the presence ofmushroom-like growths on trunks oftrees; leaves with a grayish mildewyappearance; spots on leaves, flowers,and fruits; sudden wilting or death ofa plant or branch; sap exuding frombranches or trunks of trees; andstunted growth.

Misapplication of pesticides andnutrients, air pollutants, and otherenvironmental conditions such asflooding and freezing can also mimicsome disease problems.Yellowing orreddening of leaves and stuntedgrowth may indicate a nutritionalproblem.At first glance, blossom endrot of tomato, in which the bottomof the tomato turns black, mightappear to be a disease caused bysome pathogen. It is actually causedby the plant’s inability to take up cal-cium quickly enough during periodsof rapid growth. Prevent this prob-lem with adequate moisture–addingmore calcium is of no benefit! Leafcurling or misshapen growth may bea result of herbicide application.

Pest managementpracticesPreventing pests should be your firstgoal. But it’s unlikely you will be ableto avoid all pest problems, sincesome plant seeds and disease organ-isms lay dormant in the soil foryears.

Diseases need three elements tobecome established: the disease

organism, a susceptible species, andthe proper environmental condi-tions. Some disease organisms canlive in the soil for years; other organ-isms are carried in infected plantmaterial that falls to the ground.Some disease organisms are carriedby insects. Good sanitation will helplimit some problems. Planting resis-tant varieties of plants preventsmany diseases. Rotating annual cropsin a garden also prevents some dis-eases.

You will likely have the most oppor-tunity to alter the environment infavor of the plant and not the dis-ease. Healthy, vigorous lawn and gar-den plants have a higher resistanceto pests. Plants that have adequate,but not excessive, nutrients are bet-ter able to resist attacks from bothdiseases and insects. Excessive ratesof nitrogen often result in extremelysucculent vegetative growth and canmake plants more susceptible toinsect and disease problems, as wellas decrease their winter hardiness.Proper watering and spacing ofplants limits the spread of some dis-eases. Some disease species requirefree standing water in which tospread, while other species just needhigh humidity. Proper spacing pro-vides good aeration around plants.Trickle irrigation where water isapplied to the soil and not the plantleaves may be helpful.

Barriers may be effective to excludesome pests. Mulching is effectiveagainst weeds. Fences can limit dam-age from rabbits. Row covers mayprevent insect damage on young veg-etable plants. Netting can be appliedto small fruit trees and berries tolimit damage from birds.

Integrated PestManagement (IPM)It is difficult, if not impossible, toprevent all pest problems every year.If your best prevention efforts havenot been entirely successful, youmay need to use some control meth-ods. Integrated Pest Management(IPM) relies on several techniques tokeep pests at acceptable populationlevels without excessive use ofchemical controls.The basic princi-ples of IPM include monitoring(scouting), determining tolerableinjury levels (thresholds), and apply-ing appropriate strategies and tac-tics. Unlike other methods of pestcontrol where pesticides are appliedon a rigid schedule, IPM applies onlythose controls that are needed, whenthey are needed, to control peststhat will cause more than a tolerablelevel of damage to the plant.

Monitoring is essential for a success-ful IPM program. Check your plantsregularly. Look for signs of damagefrom insects and diseases as well asindications of adequate fertility andmoisture. Early identification ofpotential problems is essential.

There are thousands of insects in thegarden, many of which are harmlessor even beneficial. Proper identifica-tion is needed before control strate-gies can be adopted. It is importantto recognize the different stages ofinsect development for several rea-sons.The caterpillar eating yourplants may be the larvae of the but-terfly you were trying to attract.Thesmall larvae with six spots on itsback is probably the young of theladybug, a very beneficial insect.Some control practices are mosteffective on young insects. Differentstages may also be more damagingthan others.

It is not necessary to kill everyinsect, weed, or disease organism tohave a healthy yard.This is where

the concept of thresholds comes in.The economic threshold is the pointwhere the damage caused by thepest exceeds the cost of control. In ahome garden, this can be difficult todetermine.What you are growingand how you intend to use it willdetermine how much damage youare willing to tolerate. Rememberthat larger plants, especially thoseclose to harvest, can tolerate moredamage than a tiny seedling.A fewflea beetles on a radish seedling maywarrant control whereas numerousJapanese beetles eating the leaves ofbeans close to harvest may not.

If the threshold level for control hasbeen exceeded, you may need toemploy control strategies. Strategiescan be discussed with theCooperative Extension Service, gar-den centers, or nurseries.

Control strategiesMechanical/physical controls Insects--Many insects can be removed byhand.This method is preferable if afew, large insects are causing theproblem. Simply remove the insectfrom the plant and drop it into acontainer of soapy water or veg-etable oil. Caution: some insects havespines or excrete oily substancesthat can cause injury to humans. Usecaution when handling unfamiliarinsects.Wear gloves or removeinsects with tweezers.

Many insects can be removed fromplants by spraying water from a hoseor sprayer. Small vacuums can beused to suck up insects.Traps can beused effectively for some insects.These come in a variety of stylesdepending on the insect to becaught. Many traps rely on the use ofpheromones--naturally occurringchemicals produced by the insectsand used to attract the opposite sexduring mating.They are extremelyspecific for each species and, there-

fore, will not harm beneficialspecies. One caution with traps isthat they may actually draw moreinsects into your yard.You shouldnot place them directly in the gar-den. Other traps are more genericand will attract numerous species.These include such things as yellowand blue sticky cards. Differentinsects are attracted to different col-ors. Sticky cards can also be usedeffectively to monitor insect pests.

Weeds--Hoeing, pulling, and mulching arethe most effective physical controlmethods for weeds.Weeding is mostimportant while plants are small.Well established plants can often tol-erate competition from weeds.

Diseases--Removal of diseased material limitsthe spread of some diseases. Cleanup litter dropped from diseasedplants. Prune diseased branches ontrees and shrubs.When pruning dis-eased trees and shrubs, disinfectyour pruners between cuts with asolution of chlorine bleach to avoidspreading the disease from plant toplant. Control insects known tospread plant diseases.

Other pests--Fences, netting, and tree trunkguards can be extremely successfulin limiting damage from small mam-mals and birds. Numerous traps arealso available to catch or kill someanimals. Caution: In many states it isillegal to move wildlife, includingsquirrels.Traps may also catch ani-mals other than the ones targeted.Check local regulations before trap-ping.

Diatomaceous earth, a powder-likedust made of tiny marine organismscalled diatoms, can be used toreduce damage from soft-bodiedinsects and slugs. Spread this materi-al on the soil--it is sharp and cuts or

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irritates these soft organisms. It isharmless to other organisms. Shallowdishes of beer can be used to trapslugs.

Biological controlsBiological controls are nature's wayof regulating populations. Biologicalcontrols rely on predators and para-sites to keep organisms under con-trol. Many of our present pest prob-lems result from the loss of predatorspecies.

Other biological controls includebirds and bats that eat insects.A sin-gle bat can eat up to 600 mosquitoes

an hour. Many bird species eat insectpests on trees and in the garden.Bacillus thuringiensis (Bt) is a bacte-ria that specifically attacks larvae ofsome insect pests including whitegrubs in the lawn and Japanese bee-tles.This bacteria is harmless todesirable species.

Chemical controlsWhen using biological controls, bevery careful with pesticides. Mostcommon pesticides are broad spec-trum in that they kill a wide varietyof organisms. Spray applications ofinsecticides are likely to kill numer-ous beneficial insects as well as thepests. Herbicides applied to weedspecies may drift in the wind orvaporize in the heat of the day andinjure non-targeted plants. Runoff ofpesticides can pollute water. Manypesticides are toxic to humans aswell as pets and small animals thatmay enter your yard.

Some common, non-toxic householdsubstances are as effective as manymore toxic compounds.A few dropsof dishwashing detergent mixedwith water and sprayed on plants isextremely effective in controllingmany soft-bodied insects such asaphids and whiteflies. Crushed garlicmixed with water may control cer-tain insects.A baking soda solutionhas been shown to help controlsome fungal diseases on roses.

When using pesticides, follow labeldirections carefully.Altering the rateof application or increasing the fre-quency of application can injuredesirable plant and animal species.

Spot applications of the pesticide tothe targeted pest can reduce theamount used and help reduce therisk of injury to non-targetedspecies. Do not apply on windy days.Read the label for information onother environmental conditions suchas temperature and rain that mayinfluence the pesticide’s effective-ness. Be aware that many so-called"organic" pesticides may be just astoxic as the synthetic or chemicalproducts.

On the farm Proper pest management on thefarm involves a variety of practices,such as rotating crops to reduce dis-ease and insect problems, and estab-lishing tall grass hedges to providehabitat for beneficial insects. Manyfarmers now monitor their fields reg-ularly--a practice called scouting--tokeep track of insect and weed popu-lations. Only when populations reacha level where an unacceptableamount of damage is likely are directcontrol measures initiated.Whenpesticides are necessary, farmers filland clean tanks away from watersources, mix only necessaryamounts, and apply only to landwhere problems exist.

Many farmers are using IPM tech-niques for effective and economiccontrol of pests. Based on monitor-ing of specific pests, farmers applyonly those pesticides needed for ade-quate control.

Lacewing

Ladybug

Praying mantis

Groundbeetle

Tricho-grammawasp

Some beneficial

insects

Controlsaphids, mealy bugs, thrips, spider mitesaphids, Colorado potato beetlealmost any insectcaterpillars that attack trees and shrubsgrubs, beetles, cutworms, army wormscorn borer, cabbage looper, other wormsweeds

Beneficial InsectGreen lacewingsLadybugsPraying mantisGround beetlesParasitic nematodesTrichogramma waspSeedhead weevils

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