managing insect and mite pests of texas...

B-13662/02

Managing Insect and

Mite Pests of

Texas Corn

Contents

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1

Policy Statement for Making Pest Management Suggestions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1

Endangered Species Regulations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2

Worker Protection Standard . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2

Biological Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2

Transgenic Corn . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2

Pre-Emergence Insect Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3Soil-inhabiting pests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3Seed treatment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3Soil treament . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4White grubs and cutworms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4Wireworms, seedcorn maggots and seedcorn beetles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5Mexican and western corn rootworm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5Southern corn rootworm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6

Seedling to Tassel Stage Insect Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6Corn leaf aphid . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6Soil cutworms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6Southwestern corn borer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7European corn borer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7Lesser cornstalk borer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7Other borers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8Corn earworm and fall armyworm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8Flea beetles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8Chinch bug . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8

Tassel to Hard Dough Stage Insect Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9Corn earworm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9Fall armyworm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10Southwestern corn borer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10European corn borer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11Spider mites . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11Adult corn rootworm beetle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13True armyworm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14Western bean cutworm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15Grasshoppers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15Sap Beetles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15

Insecicide Application Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15

Protecting Bees and Other Pollinators from Insecticides . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16

Appendix I Insect and Mite Pests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19

Appendix II Beneficial Arthropods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21

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This guide discusses insect and mite pests inthe approximate seasonal order that they damagecorn—pre-emergence, seedling to tassel and tasselto hard dough.

Policy Statement forMaking Pest ManagementSuggestions

This is not a complete listing of all productsregistered for corn and does not list all uses ofproducts mentioned. The insecticides and theirsuggested uses included in this publication reflecta consensus of Extension and research entomolo-gists based on field tests. The data from thesefield tests met the minimum requirements outlinedin the Guidelines for the Annual EntomologyResearch Review and Extension Guide RevisionConference. Products listed must conform to itsperformance standards and avoid undue environ-mental consequences.

Suggested insecticide use rates have shown suf-ficient effectiveness in tests to provide adequatecontrol in field situations. However, it is impossi-ble to eliminate all risks. Unforeseen or unexpect-ed conditions or circumstances may result in lessthan satisfactory results. Texas CooperativeExtension will not assume responsibility for suchrisks. Such responsibility shall be assumed by theuser of this publication.

Suggested pesticides must be registered andlabeled by the Environmental Protection Agencyand the Texas Department of Agriculture. The sta-tus of pesticide label clearances is subject tochange and may have changed since this publica-tion was printed.

The USER is always responsible for the effectsof pesticide residues on his livestock and crops, aswell as for problems that arise from drift or move-ment of the pesticide. Always read and followcarefully the instructions on the container label.

IntroductionCorn is subject to insect attack throughout the

growing season. Despite natural predators andparasites, some insects may reach damaging levelsand may require chemical control. However, plantdamage is not always directly related to insectnumbers. Other factors such as plant vigor,growth stage, moisture conditions, time of year,parasite and predator abundance and crop rota-tion are equally important. Therefore, chemicaltreatments should be based on careful evaluationof economic and natural control factors.

The wise use of insecticides requires that produc-ers inspect their crops frequently to determine ifdamaging numbers of insect or mite pests are pres-ent. This publication provides methods of determin-ing insect numbers and guides for determining theneed for pesticides. Because seed production cornand sweet corn are more susceptible to insect dam-age and are also more economically valuable thanfield corn, producers may need to control pests inseed and sweet corn even when fewer pests are pres-ent. Recommendations in this bulletin primarilyrefer to insect and mite control on field corn.

A few insect and mite pests attacking corn inTexas show resistance to pesticides that oncewere effective. Generally, the more extensively apesticide is used, the more rapidly resistancedevelops. Therefore, pesticides should be usedonly when needed. The actual need can be deter-mined only by frequent inspections of the crop todetermine pest numbers.

1Extension entomologists; 2Associate Department Headand Extension entomologist; 3Professor, Texas Agricul-tural Experiment Station; all of the Texas A&MUniversity System.

Managing Insect and Mite Pests ofTexas Corn

Patrick Porter, Gregory B. Cronholm, Roy D. Parker, Noel Troxclair, Carl D. Patrick,1

Pat Morrison,2 and Thomas L. Archer3

Pay particular attention to practices that ensureworker safety.

For additional information, contact your countyExtension staff; write the Extension Entomologist,2475 TAMU, Texas A&M University, CollegeStation, TX 77843-2475; or call (979) 845-7026.

Endangered SpeciesRegulations

The Endangered Species Act was enacted toprotect and to assist in the recovery of animalsand plants that are in danger of becoming extinct.In response to the Endangered Species Act, manypesticide labels now carry restrictions limiting theuse of products or application methods in areasdesignated as biologically sensitive. These restric-tions are subject to change. Refer to the Envir-onmental Hazards or Endangered Species discus-sion sections of product labels and/or call yourcounty Extension agent or Fish and WildlifeService personnel to determine what restrictionsapply in your area. Regardless of the law, pesti-cide users can be good neighbors by being awareof how their actions may affect people and theenvironment.

Worker Protection StandardThe Worker Protection Standard (WPS) is a set

of federal regulations that applies to producerswho employ people to produce a plant or plantproduct for sale. The WPS affects workers whowill apply pesticides (agricultural handlers) orwork in an area where pesticides have beenapplied (agricultural workers). Since 1995, if youare using a pesticide product with labeling thatrefers to the Worker Protection Standard, you mustcomply with it. The WPS requires that you pro-vide three basic types of pesticide protection toyour employees. You must:

• Inform employees about possible exposure.

• Protect employees from exposure.

• Mitigate pesticide exposures that employeesmight receive.

All agricultural pesticides bear a WPS statementin the “DIRECTIONS FOR USE” part of the label.For more detailed information, consult EPA publi-cation 735-B-93-001, The Worker ProtectionStandard for Agricultural Pesticides — How toComply: What Employers Need to Know (GPO

#055-000-0442-1), or call the Texas Department ofAgriculture, Pesticide Worker Protection Program,(512) 463-7717.

Biological ControlBiological control is the use of living organisms,

such as parasites, predators and disease, to controlpests. Organisms that control pests are called nat-ural enemies. In corn, natural enemies includeminute pirate bugs, spiders, lady beetles, predato-ry mites and thrips, and a variety of tiny waspsthat parasitize insect pests. In addition, weatherand inadequate food often hold insect and mitepopulations below damaging levels. It is importantto recognize the effect of these natural control fac-tors and, where possible, encourage their action.

Biological control includes the conservation,augmentation and importation of natural enemies.A producer can conserve existing populations ofnatural enemies by minimizing insecticide applica-tions and using insecticides that are more toxic tothe target pest than to the natural enemy.Augmentation involves purchasing and releasingspecimens of the natural enemies. Classical bio-logical control—the third type—involves importingnatural enemies from other countries.

Transgenic CornTransgenic corn produces some of the insectici-

dal endotoxins (poisons) found in the bacteriumBacillus thuringiensis (Bt). These proteins arehighly toxic to certain insect pests but have littleor no effect on humans, livestock, most beneficialinsects and other nontarget organisms. Becauseplanting Bt corn reduces the need for insecticides,there is less human and environmental exposureto insecticides, and the producer has lower pro-duction costs.

Extensive field testing indicates that Bt cornhybrids provide excellent control of first and usu-ally second generation European corn borers,southwestern corn borers and sugarcane borers.Bt corn varieties also may be effective in control-ling or suppressing some other lepidopterous(caterpillar) pests, including corn earworm. Thereare significant differences among the types of Btcorn and their ability to control such pests.

The presence of Bt in corn does not enhanceyield; it simply protects the yield against insectdamage. Without pests, there is no difference in

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the amount of corn produced, compared to thesame variety without Bt. However, Bt is oftenplaced in “elite” hybrids, and these may or maynot yield more than older hybrids. (See B-6090,“Bt Corn Technology in Texas: A Practical View,”Texas Cooperative Extension.)

Subject to EPA approval, transgenic corn forcorn rootworm control will be marketed in 2002.While there are several types of rootworm toxinsunder development, most depend on proteinsfrom Bacillus thuringiensis. However, these toxinsare different from those that are active againstcaterpillar pests. Rootworm-active corn will notharm corn borers, and corn borer-active corn willnot harm rootworms. Putting toxins from bothrootworm-active and lepidoptera-active corntogether in the same plant is possible, as is put-ting two different toxins for rootworms or lepi-doptera alone. These would be “stacked gene”hybrids, which will be sold in the future.

Pre-Emergence Insect Control

Soil-Inhabiting Pests White grubs, corn rootworms, cutworms, wire-

worms, sod webworms, seedcorn beetles andseedcorn maggots are the most common soilinsects attacking corn in Texas. Cultural practicesare very important in reducing damage from thesesoil pests. Growing corn on the same land yearafter year increases the damage done by certainsoil insects. For example, losses from corn root-worms may be reduced or in some cases eliminat-ed by rotating corn with soybeans or other cropsthat are not attacked by rootworms. In most areasof Texas, corn has been rotated successfully withsorghum without damage from the Mexican cornrootworm and western corn rootworm. However,in parts of South Central Texas, corn followingsorghum has been damaged by the Mexican cornrootworm, although this is a rare occurrence.Another cultural practice that reduces soil insectpests is maintaining weed-free fields throughoutthe year, because weeds are host plants for certainsoil insects.

Producers should sample their fields for whitegrubs, cutworms and wireworms before bed for-mation. If chemical treatment is necessary, soil orseed treatments are available. One method maybe more effective for a particular soil pest thananother.

Seed TreatmentIn the past, seed treatment was done by the

seed companies; however, because of restrictionson chemical use on seeds, many commercial seedcompanies are no longer treating seeds. If com-mercially treated seeds are not available, growerscan use direct seed treatment or planter box treat-ments.

Light populations of wireworms, seedcorn mag-gots, seedcorn beetles and seed-feeding ants maybe controlled by treating seeds with products con-taining lindane or lindane plus diazinon. Theinsecticide should coat each seed evenly. Use aconcrete mixer, commercial seed treater or home-made seed treater. Sprinkle 1 pint of water oneach 100 pounds of seed and mix to coat the seedwith moisture. Slowly add the correct amount ofinsecticide while mixing the seed. Mix until theinsecticide is evenly distributed on all seeds.Treated seeds should be planted within 20 days oftreatment, because long exposure to the chemicalwill affect germination in some hybrids. Do notuse treated seed for human consumption or live-stock feed.

Some insecticides are made to be applied toseed in the planter box. This method is effectiveonly against low populations of wireworms, seed-feeding ants, seedcorn beetles and seedwormmaggots. Use this soil insect control technique asdirected on the insecticide label.

Insecticides such as malathion, pirimophos-methyl (Actellic®) or methoxychlor are oftenapplied to seed to control stored grain pests.These insecticides are not effective for control ofsoil pests.

Soil TreatmentInsecticide that controls some soil pests must be

applied before the crop is planted or at plantingtime. Granular or liquid formulations may be useddepending on the producer’s equipment and thetarget insect. Granular insecticides are generallysafer. With the soil treatment method there arethree application techniques: (1) preplant broad-cast, (2) row band or T-band, and (3) in-furrow atplanting.

Preplant insecticide application. A broadcastapplication generally provides the best protectionagainst soil insects and is the only means of con-trolling heavy white grub infestations.

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Unfortunately, broadcast applications require moreinsecticide and are more expensive than row bandor in-furrow treatments. Therefore, broadcastapplications are not usually recommended.However, when broadcast applications are neces-sary, the insecticide should be applied uniformlyto the field and incorporated to a depth of 3 to 5inches immediately after application. Because oflabel changes in recent years, fewer products arelabeled for preplant broadcast application.

When corn is planted on a bed, special equip-ment is required to incorporate the insecticide to adepth of 3 to 5 inches. This is called row treat-ment. Row treatments must be made during orafter bed formation. Further cultivation or bedshaping will alter the position of the insecticide inthe row. A treated band of soil 7 to 10 incheswide and 3 to 5 inches deep, with seed placed inthe center of the treated band, is necessary toobtain the best control.

Insecticide application at planting. Insecticidesmay be applied to the soil at planting time by therow band, T-band, or in-furrow techniques. Thetechnique of choice will depend on the pestinsect and how a particular insecticide is labeled.Some insecticides applied at planting for cornrootworm control will suppress some early seasonpests, such as chinch bugs, fire ants and flea bee-tles on seedling plants. These pests will be sup-pressed for 2 to 4 weeks, depending upon theinsecticide used.

Mount the granular application equipment onthe planter with the spout just behind the openingplow or disc opener and in front of the coveringshovels or press wheel. Adjust the spouts so thetreatment band is about 6 to 8 inches wide andthe seed furrow and covering soil are treated.Incorporating the insecticide by covering shovelsis adequate. Insecticide also can be incorporatedwith short parallel chains, loop chains, presswheels, finger tines or other suitable devices.Some insecticides are labeled only for band appli-cation behind the seed covering devices. Do notapply insecticide directly on the seed unless thisuse is specifically listed on the label, becausedoing so usually results in poor seed germination.In-furrow application usually gives poor controlwhere white grub populations are high.

White Grubs and CutwormsWhite grubs are the larval stage of May and June

beetles. The larvae feed on the plant roots. Smallplants often are killed, and large plants are stuntedand may lodge before harvest. To determine theneed for white grub control before planting, exam-ine 1-square-foot soil sample for each 5 to 10 acres.An average of one white grub per square foot isenough to cause significant stand loss.

If white grub populations average approximate-ly one per square foot, adequate suppression canoften be achieved with an in-furrow or band treat-ment at planting. For surface cutworms, incorpo-rate insecticide into the top 1 to 2 inches of soil.Refer to the table in this document for cutwormcontrol on seedling corn.

Suggested Insecticides for Controlling White Grubs

Amount per Amount per acreInsecticides 1,000 feet on 40-inch(alphabetically) of row row spacing

Chlorpyrifos (Lorsban® 15G) 8.0 oz. 6.5 lb.

Tebupirimfos + cyfluthrin(Aztec® 2.1G) 6.7 oz. 5.5 lb.

Tefluthrin (Force® 3G) 4-5 oz. 3.3-4.1 lb.

Terbufos(Counter® 20CR) 6.0 oz. 4.9 lb.(Counter® 15G) 8.0 oz. 6.5 lb.

Remarks

Chlorpyrifos: Not labeled for band application. Must be in-fur-row or T-band.

Tebupirimfos + cyfluthrin: May not be used in counties adja-cent to the Gulf Coast. For applications made within 20 yardsof aquatic sites, apply as an in-furrow application only. SeeSpecial Local Needs Registration TX-00008. For optimumresults, apply as a band or T-band. In-furrow application mayprovide less control.

Tefluthrin: Apply as an in-furrow treatment.

Terbufos: Read supplemental label for information on poten-tial crop damage if used in combination with some herbi-cides. Banded or in-furrow application only.

Wireworms, Seedcorn Maggots andSeedcorn Beetles

Seed treatment with products containing lin-dane or lindane plus diazinon is generally effec-tive in controlling these soil pests. (See the sectionon seed treatment procedures for more informa-tion.) Where large populations of wireworms arepresent, follow the recommendations listed onappropriate insecticide labels. Producers shouldcheck their soil closely during land preparation to

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determine the need for seed treatment or soilapplications to control such pests.

Suggested Insecticides for Controlling Wireworms


Chlorpyrifos (Lorsban® 15G) 8.0 oz. 6.5 lb.

Fipronil(Regent® 80WG) 0.149 oz. 1.95 oz.

Tebupirimfos + cyfluthrin(Aztec® 2.1G) 6.7 oz. 5.5 lb.


Terbufos (Counter® 20CR) 6.0 oz. 4.9 lb. (Counter® 15G) 8.0 oz. 6.5 lb.

Remarks

Chlorpyrifos: Not labeled for band application. Must be in-furrow or T-band.

Fipronil: Do not apply on row spacing less than 30 inches.Do not harvest within 90 days of application. Do not plantsmall grains or other rotational crops within 12 months ofapplication or root crops within 5 months of application.

Tebupirimfos + cyfluthrin: May not be used in counties adja-cent to the Gulf Coast. For applications made within 20 yardsof aquatic sites, apply as an in-furrow application only. SeeSpecial Local Needs Registration TX-00008.

Tefluthrin: Apply as an in-furrow treatment.

Terbufos: Read supplemental label for information on potentialcrop damage if used in combination with some herbicides.

Mexican and Western Corn Rootworm Mexican and western corn rootworm beetles lay

eggs in the soil during the summer and fall, short-ly after silking time. Eggs are usually laid withinthe corn field in the upper 2 to 8 inches of thesoil, where they remain until they hatch the fol-lowing year. Time of hatching depends to someextent on soil temperature; however, eggs usuallybegin to hatch about mid-April in South Texas andabout mid-May in the High Plains and continue tohatch for several weeks. If corn roots are notavailable for the newly hatched corn rootwormsto feed on, they will die. There is only one genera-tion per year. Therefore, the best method of control-ling these two subspecies is to rotate corn with anyother crop.

Fields planted with corn year after year in areasprone to have Mexican and western corn root-worm problems (see map) generally require a soilinsecticide at planting time. In continuous cornproduction fields, an average of one or more bee-tles per plant on any sampling date during the

growing season indicates a need for a soil insecti-cide the following spring or a need to considercrop rotation. Damage from corn rootworms usu-ally occurs from mid-April through mid-May inSouth Texas and during June in the High Plains.Extensive damage to the brace roots and fibrousroots may cause plants to lodge. A “goose neck-ing” appearance occurs when lodged plants con-tinue to grow.

Suggested Insecticides for Controlling Mexican andWestern Corn Rootworms


Carbofuran See remarks See remarks(Furadan® 4F) 2.5 oz. 1 qt.

Chlorpyrifos (Lorsban® 15G) 8.0 oz. 6.5 lb.(Lorsban® 4E) 2.4 oz. 2 pt.

Tebupirimfos + cyfluthrin (Aztec® 2.1G) 6.7 oz. 5.5 lb.

Tefluthrin(Force® 3G) 4.0-5.0 oz. 3.3-4.1 lb.


Remarks

Carbofuran: Apply as a post-emergent spray by banding overthe row or by side dressing or basal spraying both sides ofthe row after corn emerges. Control will generally beimproved if the treatment is incorporated into the soil. Donot feed forage within 30 days of last application.

Chlorpyrifos: Granules are not labeled for band application.Must be in-furrow or T-band. Liquid formulation must beapplied by T-band application only. Applications made usinga band width less than 5 to 6 inches may cause phytotoxicityunder certain environmental conditions (e.g., cool tempera-tures, wet conditions and light soils).

Tebupirimfos + cyfluthrin: May not be used in counties adja-cent to the Gulf Coast. For applications made within 20 yardsof aquatic sites, apply as an in-furrow application only.


PRECAUTION: Certain sulfonylurea herbicides andorganophosphate insecticides used in the same crop year oncorn may cause severe crop injury. Please read pesticidelabels carefully.

IMPORTANT: The use of the same soil insecticides year afteryear in the same field is not a good practice. Producers areencouraged to rotate organophosphate (chlorpyrifos, terbufos,tebupirimfos) with other (tefluthrin, cyfluthrin, carbofuran)soil insecticides each year for best results.

For all band applications, apply in a 6- to 8-inch band justbehind seed drop and in front of covering shovels and presswheel or chain drag. Soil incorporation to a depth of about 1inch is important.

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Southern Corn Rootworm The southern corn rootworm deposits its eggs in

soil after the corn is in the seedling stage. There-fore, crop rotation will not provide adequate con-trol of this insect. Unlike the Mexican and westerncorn rootworms, more than one generation ofsouthern corn rootworm may occur per year. Thisspecies is considered a minor corn pest in mostareas of Texas where corn is planted in fields thatwere not grassy or weedy the previous year.

In the Gulf Coast region (see map above), how-ever, the southern corn rootworm has been a sig-nificant pest. Where there is a history of infesta-tions along with losses in plant stands in previousyears, an in-furrow or band pesticide applicationshould be considered.

With insecticides that can be applied in-furrow,field experiments show that in most fields one-halfthe maximum rate listed in the following table pro-vides the most favorable economic returns for con-trol of southern corn rootworm. However, in fieldswhere heavy infestations occur each year, it wouldbe advisable to use the higher rates.

Suggested Insecticides Applied At Planting for ControllingSouthern Corn Rootworm


Carbofuran (Furadan® 4F) 2.5 oz. 1 qt.

Chlorpyrifos(Lorsban® 15G) 8.0 oz. 6.5 lb.



Remarks

Carbofuran: Apply at planting directly into the seed furrow. Donot feed forage within 30 days of last application.


PRECAUTION: Certain sulfonylurea herbicides and organophos-phate insecticides used in the same crop year on corn may resultin severe crop injury. Please read pesticide labels carefully.

IMPORTANT: The use of the same soil insecticide year afteryear in the same field is not a good practice. Producers areencouraged to rotate organophosphate (chlorpyrifos, terbufos)with other (tefluthrin, carbofuran) soil insecticides each year.

For all band applications, apply in a 6- to 8-inch band justbehind seed drop and in front of covering shovels and presswheel or chain drag. Soil incorporation to a depth of about 1inch is important.

Seedling to Tassel StageInsect Control

Corn Leaf Aphid Fields in the seedling stage rarely require treat-

ment for corn leaf aphid. Yield losses haveoccurred only where corn leaf aphids causedstand loss to seedling plants. Pre-tassel and latergrowth stages can tolerate large numbers ofaphids without economic damage.

Soil CutwormsCutworms are dingy, grayish-black, smooth

“worms” that are the larval stages of several differ-ent moths. Cutworms are active at night and dam-age seedling corn by cutting the stalk just aboveground level. Large numbers of cutworms may befound in grassy or weedy areas. Most cutwormspecies hide in the soil during the day and are notvisible on the plants.

When cutworms are damaging plant stands, anapplication of insecticide by air or ground usually

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will give adequate control. Best results areobtained when insecticides are applied in the lateafternoon. If the soil is dry, cloddy or crusty at thetime of treatment, control may not be as effectiveas in moist soil.

Suggested Insecticides for Controlling Cutworms

Days from lastInsecticides Amount application to: (alphabetically) per acre Harvest Grazing Chlorpyrifos

(Lorsban® 4E) 1-2 pt. 35 14 Esfenvalerate

(Asana® XL 0.66E) 5.8-9.6 oz. 21 21

Permethrin(Ambush® 2E) 6.4-12.8 oz. 30 30(Pounce® 3.2EC 4.0-8.0 oz. 30 no(Pounce® 1.5G) 6.7-13.3 lb. 30 no

Lambda-cyhalothrin (Warrior® CS) 1.92-3.20 oz. 21 See label

Remarks

Chlorpyrifos: It is preferable to apply Lorsban when soil ismoist and cutworms are active on or near the soil surface.Do not feed treated corn fodder to meat or dairy animalswithin 35 days after last treatment.

Permethrin: Pre-emergent use—Apply from 5 days prior toplanting until the emergence of the crop. Apply as a broad-cast spray in a minimum of 20 gallons of finished spray/acrewith ground equipment. Foliar use—Apply prior to ear for-mation by ground.

Southwestern Corn BorerSouthwestern corn borers emerge from corn

stubble in the spring to lay eggs on whorl-stagecorn. Corn adjacent to or near unplowed stubbletypically experiences higher densities of southwest-ern corn borer larvae feeding in the whorl. Eggsare laid on the upper and lower surfaces of expan-ded leaves in the whorl. Freshly laid eggs arecreamy white; after about 24 hours, three redbands appear on each egg. Small larvae hatch fromthe eggs in about 5 days and begin feeding in thewhorl. The typical rows of holes across the leafsurface associated with whorl feeders becomeapparent as leaves unfold. Another leaf symptomcommonly associated with southwestern corn borerfeeding in the whorl is longitudinal, transparentareas on the leaf where young larvae feed onlypartially through the leaf tissue. After the larva hasfed in the whorl, it crawls down the plant andbores into the stalk. Corn borer larvae reach alength of 1 to 11/2 inches. They have a regular pat-tern of raised black dots on a creamy white body.

First generation eggs and larvae are difficult todetect because infestations seldom exceed 5 per-

cent of plants. However, if infestations are greatenough to warrant treatment, applications shouldbe made before borers leave the whorl and enterthe stalk. For recommended insecticides, refer tothe southwestern corn borer table in the “Tassel toHard Dough Stage” of this guide.

European Corn BorerEuropean corn borer was first discovered in

Texas High Plains corn in 1978. Economicallydamaging infestations can be found in most corngrowing areas of the Texas Panhandle. Borersoverwinter as full-grown larvae in corn stalks,corn cobs, weed stems or other corn field debris.Pupation occurs in May, and first generationmoths begin to emerge in late spring. Moths arefirst attracted to dense vegetation around corn andremain there for a few days while they mate.Mated females return to the corn fields to layeggs. They are attracted to the tallest fields (atleast 22- to 35-inch extended leaf height). Theeggs, 15 to 30 in a mass, overlap like fish scalesand are normally deposited near the midribs onthe undersides of the leaves. Eggs hatch in 3 to 7days. Larvae move to the whorl to feed beforeentering the stalk for pupation.

To determine the need for insecticide applica-tion to control first generation European corn bor-ers, examine five random samples of 20 consecu-tive plants each. An insecticide application is justi-fied if 50 percent of the plants are infested withan average of at least one live larva per plant. Forrecommended insecticides, refer to the Europeancorn borer table in the “Tassel to Hard DoughStage” of this publication.

Lesser Cornstalk BorerThe lesser cornstalk borer occasionally attacks

seedling corn. The small, slender larva remains inthe soil in a silken tube and injures plants by feed-ing on the crown area of the plant at the soil line.

These insects may occur in damaging numberson sandy soils and can become more numerousunder dry conditions. Rainfall and irrigation willkill many larvae, so irrigation timing and theamount of water applied at each irrigation willinfluence control. Insecticides applied at plantingfor corn rootworms may control other soil pestssuch as lesser cornstalk borer.

Applications of Terbufos (Counter CR) for cornrootworms have provided suppression of lessercornstalk borers. Careful inspection during the

7

8

seedling stage is important in areas where this insecthas been a problem. Base any treatments on theactual plant damage and the presence of larvae.This insect does not usually affect larger corn plants.

Suggested Insecticides for Controlling Lesser CornstalkBorer

Days from lastInsecticides Amount application to: (alphabetically) per acre Harvest Grazing

Chlorpyrifos(Lorsban® 15G) 3.3-9.8 lb. 35 14(Lorsban® 4E) 2-3 pt. 35 14

Remarks

Chlorpyrifos: Do not feed treated corn fodder to meat or dairyanimals within 35 days after last treatment.

Other Borers In recent years, most borer damage to corn in

the Lower Rio Grande Valley and along the GulfCoast has been caused by the Mexican rice borer,the sugarcane borer and the neotropical borer(see map).

These borers typically attack corn in the pre-tassel stage. They feed on the leaves for a shorttime before boring into the stalks. Yield losses areminor unless stalk lodging occurs. Bored stalksmost frequently fall during ear filling or ear matu-ration, and lodging is often associated with highwinds. The stalks may break at any point andusually do not break near the soil level as withsouthwestern corn borer infestations. Control ismost successful when fields are scouted closelyand treated before larvae bore into stalks.

Corn Earworm and Fall ArmywormCorn earworm and fall armyworm moths

deposit eggs on leaves. Newly hatched larvaebegin to feed in the whorl. Larval feeding willcause the leaves to appear ragged, but insecticidetreatments are seldom recommended and econom-ical control is seldom achieved.

Flea BeetlesFlea beetles are very tiny, shiny black or green-

ish black insects that will jump when disturbed.They range in size from smaller than a pinhead toseveral times as large. They damage corn plantsup to 18 inches tall, primarily by feeding on theleaves. Damaged leaves have a whitened, bleach-ed appearance. Plant growth is retarded as theleaves wilt and hang limp.

Fields kept clean of weeds the previous seasonseldom suffer significant flea beetle injury. When

sufficient numbers of flea beetles are damagingcorn, an application of insecticide may be necessary.

Suggested Insecticides for Controlling Flea Beetles


Carbaryl(Sevin® 80WSP) 1.25-2.5 lb. 48 14(Sevin® XLR Plus 4 lb.) 1.0-2.0 qt. 48 14

Esfenvalerate (Asana® XL 0.66EC) 5.8-9.6 oz. 21 21

Methyl parathion (4.0 lb.) 0.50 pt. 12 1

RemarksChlorpyrifos: Do not feed treated corn fodder to meat ordairy animals within 35 days after last treatment.

Chinch Bug Adult chinch bugs are about 1/6-inch long with

black bodies and reddish-yellow legs. When fullydeveloped, the white wings are marked with a tri-angular black spot near the middle of the back onthe outer wing margin. When viewed from above,the insect appears to have a white “X” or whitehourglass on the back.

Adult and immature chinch bugs suck plantjuices and cause reddening of the leaves. Damageby chinch bugs normally occurs from seedlingemergence until the plants are 18 inches tall.Large numbers of chinch bugs can move into acornfield by crawling or flying from wild bunch

grasses or small grains. Once in the field, theycongregate and feed behind the leaf sheaths ofthe corn plant.

Suggested Insecticides for Controlling Chinch Bugs


At-Plant

Chlorpyrifos(Lorsban® 15G) 6.5 lb. 35 14(Lorsban® 4E) 1-2 pt. 35 14

Terbufos (Counter® 20CR) 4.9 lb. 30 30(Counter® 15G) 6.5 lb. 30 30

Post-Plant

Carbaryl (Sevin® XLR Plus 4 lb.) 1-2 qt. 48 14(Sevin® 80WSP) 1.25-2.5 lb. 48 14

Chlorpyrifos (Lorsban® 4E) 1-2 pt. 35 14

Lambda-cyhalothrin(Warrior® 1CS) 3.84 oz. 21 See label

Remarks

For post-plant application, use only ground applicationequipment and direct the spray nozzles at the infested por-tions of the plants. Control is difficult on larger plants.

Carbaryl: For optimum control, apply 20 gallons of water peracre by ground and direct the spray towards the bases ofstalks to provide thorough coverage.

Chlorpyrifos: Do not feed treated corn fodder to meat or dairyanimals within 35 days after last treatment. For Lorsban 15G,a T-band is more effective than an in-furrow application. In-furrow applications should be considered as suppressiononly. Do not feed treated corn fodder to meat or dairy ani-mals within 35 days after last treatment. Apply Lorsban 4Ewith sufficient water to ensure a minimum spray volume of20 to 40 gallons per acre and 40 psi using ground equipment.On corn less than 6 inches tall, use a 9- to 12-inch band overthe row. On corn higher than 5 inches, use drop noz.zlesdirected at the bases of the plants.

Terbufos: Apply at planting time in-furrow, placing granulesdirectly in the seed furrow behind the planting shoe. Forearly season control of light to moderate infestations.

In fields with a history of early-season, econom-ically damaging chinch bug populations (seemap), at-plant soil-incorporated insecticides cansuppress the development of chinch bug popula-tions. Granular formulations may provide 2 to 3weeks of protection, provided sufficient rainfall isreceived following application to wash the insecti-cide off of the granules. Young plants should beclosely monitored for chinch bugs and feedingdamage after germination, particularly during dryperiods, even when at-plant insecticides are used.

Make at least five random checks in the field.Insecticide should be applied when two or moreadult chinch bugs are found on 20 percent ofseedlings less than 6 inches high. On taller plants,apply insecticides when immature and adult bugsare present on 75 percent the plants.

9

Tassel to Hard Dough StageInsect Control

Corn Earworm Corn earworm moths begin laying eggs on

leaves and silks soon after tassel emergence andbefore pollination. After hatching, larvae tunnelinto the silk channel to feed. The silks that arefed upon have usually completed pollination;therefore, a loss of pollination is generally not aproblem. Later instar larvae can be found feedingon kernels at the tip of the ear. Ear damage isusually minor, although an occasional field mayhave excessive damage.

Corn earworm control is difficult since egg lay-ing is extended through the silking period andcontinues after the completion of pollination(brown silk stage). Insecticides used for controlmust be applied frequently because untreatedsilks are exposed daily as silks elongate. Controlefforts are usually costly and inconsistent.Currently, control strategies are not suggested incommercial field corn.

Fall Armyworm The fall armyworm is a sporadic pest of corn. It

migrates north during the growing season fromoverwintering sites in south Texas and northernMexico. Infestations occurring from tassel todough stage can be very damaging. Larvae feedon ears and ear shanks and behind leaf collars.Heavy infestations may cause substantial yieldlosses because larvae feed directly on the ear.Additional losses can occur when shank feedingcauses ears to drop and when stalks lodge as aresult of feeding damage to the nodes.

Fall armyworm larvae range from a light tan toa dark green or black color. Light and dark stripesrun longitudinally on the body. Dark spots orbumps occur in a pattern over the body, especial-ly when viewed from the top. The head of a larvahas a prominent inverted “Y” in a light color thatcontrasts with the dark head capsule.

Scouting for fall armyworms can be difficult.Check corn leaves and grasses in the furrow foregg masses. There may be 50 to 100 eggs permass. Also check for small larvae behind leaf col-lars and at the bases of primary and secondaryears. Small larvae differ from late instar larvae inthat they are pale tan in color and have a smallblack spot on each side toward the head. This dis-tinguishes them from corn earworm and south-western corn borer larvae.

Currently, Texas does not have an establishedeconomic threshold for this pest. If control is nec-essary, it should be targeted at small larvae beforethey enter the primary ear.

Southwestern Corn BorerThe southwestern corn borer is a major corn

pest on the High Plains (see map on page 8).Although it also occurs in far West Texas andNortheast Texas, it is not economically importantin these regions. Damage is caused by larvae tun-neling in the stalk and later girdling the plant,which results in lodging. Moths emerge from cornstubble and weed hosts in the spring to lay firstgeneration eggs on whorl stage corn. On the HighPlains, first generation larvae mature and pupatein the stalk in July. Moths begin emerging aboutmid-July and lay eggs of the second generation.

Second generation eggs are usually laid aftertasseling has occurred. About three-fourths ofthese eggs are laid on the upper surfaces of themiddle seven leaves — the ear leaf, two leaves

above and four leaves below the ear leaf. Eggsare laid singly or in masses of two to three ormore. Eggs overlap like fish scales or shingles.Freshly laid eggs are creamy white. One day later,three red bands appear across each egg. Eggshatch in about 5 days. Small larvae feed behindleaf collars and ears and beneath the shucks ofthe primary ear. Older larvae bore into the stalkand continue feeding. Mature corn borer larvaereach 1 to 1 1/2 inches in length. They are dullwhite and have a regular pattern of raised blackdots over the body. As plants reach maturity, lar-vae prepare for overwintering in the base of thestalk by girdling the plant from 1 to 6 inchesabove the ground. Wind can easily lodge girdledplants. Lodged plants are difficult to harvest, andyields are reduced.

Southwestern corn borer larvae overwinter in thestalk base or root crown. They are insulated by afrass (excrement) plug in the stalk and by the sur-rounding soil. One of the most effective borer con-trol methods is to destroy this winter habitat toreduce spring moth emergence. A single tandemdisc cultivation or shredding will expose larvae tocold, dry winter conditions while leaving sufficientresidue to prevent soil erosion. The shredder mustbe set to cut stalks at the soil surface to removethe protective frass plug. Shredding is particularlycompatible with grazing and minimum tillage oper-ations because it does not bury plant materials, butit does expose corn borer larvae. Also, stalk shred-ding can be performed even when the soil isfrozen. Double disking and deep plowing areeffective methods if soil erosion is not a problem.High larval mortality is obtained when cultivationor shredding is performed before mid-January.Timely stubble destruction will reduce local infesta-tions of first generation larvae. However, producersmust cooperate by destroying stubble to effectivelyreduce southwestern corn borer populationsthroughout an area.

Early planted corn is less susceptible to cornborer plant lodging. A plant population that pro-motes large, healthy stalks, combined with properfertilization and adequate irrigation, help preventlodging of corn borer-infested stalks. Crop rota-tion, use of early-maturing varieties and an earlyharvest with equipment designed to pick uplodged stalks help reduce yield losses.

Insecticide treatments are usually directedtoward second generation larvae. Insecticide

10

should be applied when 20 to 25 percent of theplants are infested with eggs or newly hatched lar-vae. Check for egg masses to determine thepotential infestation and the correct timing ofinsecticide application.

Producers can use computer predictions of sec-ond generation moth flight and egg lay to planfield scouting to detect infestations. Contact yourcounty Extension agent for egglaying predictionsin your area.

Suggested Insecticides for Controlling SouthwesternCorn Borer


Bifenthrin (Capture® 2EC) 2.1-6.4 oz. 30 30

Carbaryl (Sevin® 80WSP) 1.25-2.5 lb. 48 14(Sevin® XLR Plus 4 lb.) 1.0-2.0 qt. 48 14

Carbofuran (Furadan® 4F) 1.0-2.0 pt. 30 30

Chlorpyrifos (Lorsban® 4E) 1.5-2 pt. 35 14(Lorsbsan® 15G) 6.5 lb. 35 14

Esfenvalerate (Asana XL® 0.66E) 5.8-9.6 oz. 21 21

Lambda-cyhalothrin (Warrior® 1CS) 2.56-3.84 oz 21 See Label

Permethrin (Ambush® 2E) 6.4-12.8 oz. 30 30(Pounce® 3.2EC) 4.0-8.0 oz. 30 No(Pounce® 1.5G) 6.7-13.3 lb. 30 No

Remarks

Research data demonstrate that the use of cabaryl, chlorpyri-fos, and pyrethroid (esfenvalerate, lambda-cyhalothrin, per-methrin) insecticides can increase mite densities on corn.

Chlorpyrifos: Do not feed treated corn fodder to meat or dairyanimals within 35 days after last treatment. Lorsban 15G is notlabeled for band application. Must be in-furrow or T-band.

Carbofuran: Do not make more than two foliar applicationsper season or more than one foliar application if Furadan 4Fwas used as a soil application. Do not use Furadan as a foliartreatment on seed corn. Do not enter treated fields within 14days of application unless full protective equipment is worn.

Permethrin: Do not apply after silks begin to turn brown.

European Corn BorerThe second generation of European corn borers

usually causes higher yield losses than the first

generation. Second generation moths that emergein mid-summer are attracted to dense vegetationaround corn fields, primarily for mating. Matedfemales return to recently tasseled corn to layeggs. Most of the egg masses will be laid on theundersides of leaves nearest to and including theear leaf. Eggs are white, and a black dot (the headof the young larva) can be seen just before hatch-ing. Eggs will hatch in 3 to 5 days. After hatching,approximately 75 percent of the small larvaemove to the leaf axils, and the remaining 25 per-cent go to the ear sheath and collar tissue. Yieldlosses result from damage caused by larval tunnel-ing, ear droppage and direct kernel feeding.

Suggested Insecticides for Controlling European CornBorer


Bacillus thuringiensis (Dipel® 10G) 10 lb. 0 0 (Dipel® ES) 1.5-2.5 pt. 0 0

Bifenthrin(Capture® 2EC) 2.1-6.4 oz. 30 30

Carbofuran (Furadan® 4F) 1.5 - 2 pt. 30 30

Chlorpyrifos(Lorsban® 4E) 1.5 - 2 pt. 35 14(Lorsbsan® 15G) 6.5 lb. 35 14

Esfenvalerate (Asana XL 0.66E) 7.8-9.6 oz. 21 21

Lambda-cyhalothrin (Warrior® 1CS) 2.56-3.84 oz. 21 See Label

Permethrin (Ambush® 2E) 6.4-12.8 oz. 30 30(Pounce® 3.2EC) 4.0-8.0 oz. 30 No(Pounce® 1.5G) 6.7-13.3 lb. 30 No

Spinosad (Tracer® 4SC) 2.0-3.0 oz. 28 7

Remarks

Research data demonstrate that the use of cabaryl, chlorpyri-fos, and pyrethroid (esfenvalerate, lambda-cyhalothrin, per-methrin) insecticides can increase mite densities on corn.

Chlorpyrifos: Do not feed treated corn fodder to meat or dairyanimals within 35 days after last treatment. Lorsban 15G isnot labeled for band application. Must be in-furrow or T-band.

Carbofuran: Do not make more than two foliar applicationsper season or more than 1 foliar application if Furadan 4Fwas used as a soil application. Do not use Furadan as a foliartreatment on seed corn. Do not enter treated fields within 14days of application unless full protective equipment is worn.

Permethrin: Apply prior to the brown silk stage.

Spinosad: Suggested for first generation only.

11

To determine the need for an insecticide appli-cation, examine a minimum of five random sam-ples of 20 consecutive plants each. An insecticideapplication is justified if an average of 10 to 20hatched and unhatched egg masses can be foundper 100 plants. Two applications may be neces-sary to satisfactorily control European corn borer.

Spider Mites Infestations of spider mites sufficient to cause

economic harm occur primarily on corn in theTexas High Plains and Rio Grande Valley. Largenumbers of spider mites may occur on corn aftertassels appear. Mites first appear on the lowerleaves, but they may move upward until all theleaves (and in extreme cases the entire plant) arekilled. Heavy infestations cause extensive webbingon the leaves and may be associated with stalk rotand lodging. Periods of hot, dry weather favor arapid increase of mite populations. Using insecti-cide to control other pests is an important factortriggering mite increases. Infestations may killbeneficial insects that usually keep spider mitenumbers low. Mite numbers may also increasewhen excessive amounts of fertilizer are used;therefore, it is important to test soil and applyonly the amount of fertilizer needed. Proper irriga-tion timing will help plants withstand mite feedingdamage. The most important time to preventwater stress is during tassel and early grain filling.

Both the Banks grass mite and twospotted spi-der mite can occur on corn in Texas. The Banksgrass mite is the predominant species in early andmid-season, and it is more widely distributed thanthe twospotted spider mite. A few fields, however,will have high numbers of twospotted spidermites. It is important to distinguish between thesetwo species because presently registered miticidesgenerally will not control twospotted spider mitesin tassel-stage corn. The most useful characteristicfor distinguishing between these two species isthe pattern of pigmentation spots on the body.The adult twospotted spider mite has a welldefined spot on each side of the front half of theabdomen. The spots on the adult Banks grassmite extend all the way down both sides of thebody, sometimes almost touching at the rear of

the body. Additionally, twospotted spider mitesproduce more webbing than Banks grass mites.

To decide whether or not Banks grass mitesand/or twospotted spider mites should be con-trolled, estimate the per acre control cost (miticideplus application costs) and the expected value ofthe crop (yield X value). A two-step samplingprocess is necessary. The field can be quicklychecked to determine the percentage of plantsinfested by mites. Divide the number of mite-infested green leaves (a leaf is infested if a mitecolony of any size is on the leaf) by the numberof green leaves per plant. If the plant equals orexceeds the percentage of infested leaves neededto cause yield loss, based on the table below,then determine the percentage of the leaf area onthe plant that is damaged by mite feeding.

Mite damage is any light colored (chlorotic)areas on the plant that result from mite feeding.Remember to look at all the leaves on a plant toestimate how much of the total leaf area is dam-aged by mite feeding. Do not base the damageestimate on infested leaves only, or the damagerating will be overestimated. Dead leaves equal100 percent damage for that leaf. Now, calculatethe average percentage of the leaf area damaged.If both the percentage of the leaves infested andthe percentage of the leaf area damaged equal orexceed the values for the crop on the tablebelow, it is time to spray. If the miticide to beapplied provides rapid control (less than 3 daysafter application), you can wait up to 1 weekbefore spraying the corn. However, if the miticidewill not provide rapid control, spray the fieldimmediately. This economic injury level may beused to make control decisions on field or foodcorn before the full dent growth stage. Mite feed-ing after full dent will not cause yield loss, but itmay contribute to premature plant lodging if mitfeeding damage is severe and the crop is stressed.Mite feeding will not slow dry-down of the grain.Research has shown that adding oil to miticideshelps them penetrate the canopy.

12

Suggested Miticides for Controlling Twospotted SpiderMites


Propargite See remarks(Comite® II 6 lb.) 2.25-3.38 pt. 30 See label

Sulfur (6 lb. flowable) 4 qt. 0 0

Remarks

Propargite: Ground application must use a minimum of 20gallons of water per acre. A minimum of 5 gallons of waterper acre are required for aerial application. Only one applica-tion can be made per year. Do not plant small grains in rota-tion within 82 days after application.

Sulfur: This is the only material that has been partially effec-tive in the Trans-Pecos area of Texas. Thorough plant cover-age is required.

Suggested Miticides for Controlling Banks Grass Mites



Carbofuran + Dimethoate 2 pt Furadan + 30 See label (Furadan® 4F) +

Dimethoate (see formu- dimethoate aslations listed below) listed below

Dimethoate(Dimethoate 4 EC) 0.67-1 pt. 14 14(Dimethoate 5 lb.) 8.4-12.8 oz. 14 14(Dimethoate 400) 0.67-1 pt. 14 14

Propargite See remarks(Comite II 6 lb.) 2.25-3.38 pt. 30 See label

Sulfur (6 lb. flowable) 4 qt. 0 0

Remarks

Bifenthrin: ULV applications are prohibited. Often used in com-bination with dimethoate.

Carbofuran: Do not make more than two foliar applicationsper season or more than one foliar application if Furadan 4Fwas used as a soil application. Do not use Furadan as a foliartreatment on seed corn. Do not enter treated fields within 14days of application unless full protective equipment is worn.

Dimethoate: Not labeled for Trans-Pecos area of Texas. Thisproduct has often been used in combination with pyrethroidsfor the control of mites. There is no demonstrated advantageto mixing dimethoate with Propargite. Heavy infestations mayrequire an alternate chemical.

Propargite: Ground application must use a minimum of 20 gal-lons of water per acre. A minimum of 5 gallons of water peracre are required for aerial application. Only one applicationcan be made per year. Do not plant small grains in rotationwithin 82 days after application.

Sulfur: This is the only material that has been partially effec-tive in the Trans-Pecos area of Texas. Thorough plant cover-age is required.

Adult Corn Rootworm BeetleAdult rootworm beetles feed on leaves, pollen

and tassels, but they prefer silks. When adults arenumerous (eight to 10 per plant) during the greensilk stage and the silks are chewed back to within

13

Economic Injury Level for the Banks Grass Mite and/or Twospotted Spider Mite on Corn, Based on the Percent-ageof Infested leaves Per Plant/ Percentage of Leaf Area Damaged

ControlCost - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -Market value ($) per acre - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

� ��/� ��/� ��/� �/� / /� �/� �/� �/� �/� /�� /�� /�� /�� /� ��/� ��/ ��/� ��/� ��/� �/� �/�� /�� /�� /�� /�� /�� /�� /� ��/� ��/� �/ ��/

�� /�� /�� /�� /�� /�� /� �/�� /�� /�� /�� /�� /�� /�� /�� /�� /�� /� ��/�� /� ��/�� /�� /��

1/2 inch of the shuck, poorly filled ears may resultfrom poor pollination. When this or excessive leafdamage occurs, it is profitable to control the beetles.

Controlling adult beetles usually will reduce thenumber of eggs laid in the field. However, insecti-cides can cause an outbreak of spider mites bydestroying natural enemies. Spider mites can bevery damaging to corn and are difficult to control.Insecticide treatments for adult beetle controlshould be used only when necessary.

In addition to conventional insecticides, thereare baits containing reduced rates of insecticideslabeled for control of adult corn rootworms.These baits attract only corn rootworm beetlesand do not destroy beneficial insects and predato-ry mites. Therefore, there is less risk of a spidermite outbreak following application than withmany other conventional insecticides. These baitshave been most effective when all the corn pro-ducers in an area cooperate to treat their fieldsand thus reduce rootworm numbers across a largearea. An effective program requires an organizedfield scouting program, accurate timing of treat-ments and proper application of the baits.

Suggested Insecticides for Controlling Mexican andWestern Corn Rootworm Beetles


Carbaryl(Sevin® 80WSP) 1.25-2.5 lb. 48 14 (Sevin® XLR Plus 4 lb.) 1.0-2.0 qt. 48 14

Malathion(Atrapo® ULV 9.9 lb.) 4.0 oz. 5 See label(Fyfanon® ULV 9.9 lb.) 4.0 oz. 5 5

Methyl parathion (Penncap-M® 2F) 1.0-2.0 pt. 12 12 (Methyl parathion 4.0E) 0.5 pt. 12 12

Remarks

Research demonstrates that the use of cabaryl, chlorpyrifosand pyrethroid (esfenvalerate, lambda-cyhalothrin, bifenthrin,permethrin) insecticides can increase mite densities on corn.Ethyl and methyl parathion are also associated with miteincrease on corn.

Note: Application of the insecticides listed above duringpollen shed will destroy foraging honey bees.Chlorpyrifos: Do not feed treated corn fodder to meat or dairyanimals within 35 days after last treatment.

Methyl parathion: Do not apply during pollen shed if bees areforaging in the area.

True Armyworm True armyworms occasionally cause heavy

damage to corn in the High Plains, and they mayoccur in other areas of Texas as well. True army-worm activity is usually heaviest in fields with jun-glerice (watergrass) and johnsongrass in the fur-rows or in fields that have hail-damaged leaves.True armyworms may go unnoticed as popula-tions build up on the weeds in the furrows. Then,when the weeds are consumed and larvaeincrease in size, they begin feeding on cornleaves. Large larvae can defoliate corn plants rap-idly. When defoliation is excessive, yield reduc-tions will occur, and premature drying of the stalkmay lead to lodging problems. Chemical treat-ments should be applied when an average of threeleaves per plant are destroyed by larval feeding.

Suggested Insecticides for Controlling True Armyworms


Carbaryl (Sevin® 80WSP) 1.25-2.5 lb. 48 14 (Sevin® XLR Plus 4 lb.) 1.0-2.0 qt. 48 14

Chlorpyrifos(Lorsban® 4E) 1-2 pt. 35 14

Esfenvalerate(Asana® XL 0.66E) 5.8-9.6 oz. 21 21

Methomyl: (Lannate® 90SP) 0.25-0.5 lb. 21 See label(Lannate® 2.4LV) 0.75-1.5 pt. 21 See label

Methyl parathion (Penncap-M® 2F) 2.0-3.0 pt. 12 12(Methyl parathion 4E) 0.5 pt. 12 12

Malathion (Atrapa® ULV 9.9 lb.) 4.0 oz. 5 See label(Fyfanon® 9.9 lb.) 4.0 oz. 5 5

Permethrin (Ambush® 2E) 6.4-12.8 oz. 30 30(Pounce® 3.2EC) 4.0-8.0 oz. 30 no

Remarks

Research demonstrates that the use of carbaryl, chlorpyrifosand pyrethroid (esfenvalerate and permethrin) insecticidescan increase mite densities on corn. Ethyl parathion andmethyl parathion are also associated with mite increase oncorn.

Note: Application of the insecticides listed above duringpollen shed will destroy foraging honey bees.


Methyl parathion: Do not apply during pollen shed if bees areforaging in the area.

14

Western Bean Cutworm Economic damage from western bean cutworm

is limited to the extreme northwest corner of theTexas Panhandle. Moth activity begins in earlyJuly, with egg lay following shortly thereafter.Eggs are laid on the upper surfaces of the cornleaves in masses of 5 to 200. They turn from apearly white at egg lay to bluish-black by hatch-ing time. At hatching the young cutworms feed onthe egg shell and then move to one of two siteson the corn, depending on the stage of corndevelopment. If the corn has not tasseled, youngcutworms will feed in the whorl on the develop-ing tassel. If the corn has tasseled, the young cut-worms move to the developing ear and feed onthe silk. As the larvae mature, they begin feedingon developing grain. Insecticide treatments shouldbe made when 14 percent of the plants are infestedwith eggs or larvae and corn is 95 percent tasseled.

Suggested Insecticides for Controlling Western BeanCutworm



Carbaryl (Sevin® 80WSP) 2.5 lb. 48 14(Sevin® XLR Plus 4 lb.) 2.0 qt. 48 14

Esfenvalerate (Asana® XL 0.66E) 2.9-5.8 oz. 21 21

Lambda-cyhalothrin(Warrior® 2CS) 1.92-3.2 oz. 21 See label

Methyl parathion(Penncap-M® 2F) 3.0-4.0 pt. 12 12

Remarks


Methyl parathion (Penncap-M®): Do not apply during pollen shedif bees are foraging in the area.

Grasshoppers Grasshoppers occasionally cause damage to

corn. Damaging infestations need to be controlledearly while grasshoppers are small and still incrop border areas. Ten or more nymphs per squareyard in crop margins warrant control measures.

Suggested Insecticides for Controlling Grasshoppers



Carbofuran (Furadan® 4F) Sec. 24C 0.25-0.5 pt. 30 30

Chlorpyrifos(Lorsban® 4E) 0.5-1.0 pt. 35 14

Esfenvalerate(Asana® XL 0.66E) 5.8-9.6 oz. 21 21

Lambda-cyhalothrin(Warrior® 2SC) 2.56-3.84 oz. 21 See label

Remarks

Carbofuran: Do not make more than two foliar applications perseason or more than one foliar application if Furadan 4F wasused as a soil application. Do not use Furadan as a foliartreatment on seed corn. Do not enter treated fields within 14days of application unless full protective equipment is worn.


Sap BeetlesCorn sap beetles or picnic beetles are attracted

to decaying vegetable matter and often invadecorn ears damaged by insects. These are small(1/3-inch) black or brown beetles, which mayhave orange to yellow spots on their wing covers.These secondary invaders are not attracted tohealthy ears, but feed on decaying plant tissueand the associated micro-organisms.

Insecticide ApplicationMethods

Ground machines or aircraft may be used toapply most insecticides. For best aerial applicationresults, flag the swaths so they meet or overlap.Spray applications are more effective and drift isreduced when wind velocity is not more than 10miles per hour. Avoid spraying when plants arewet. Nozzle size and number, ground speed andpressure affect the rate of spray solution outputper acre; therefore, calibrate the sprayer carefullyand often to ensure that the recommendedamount of insecticide is applied. One nozzle perrow is usually adequate for young row crops, buttwo or three nozzles per row may be desirable onlarger plants for adequate coverage.

Certain insecticides and miticides can beapplied in irrigation water (chemigation) throughcenter pivot and stationary irrigation systems.Chemigation can reduce application costs and, in

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some cases, requires less insecticide because ofimproved crop coverage as compared to conven-tional application methods. Chemigation requiresan initial investment in chemical injection equip-ment and additional management time.

Safe and effective chemigation requires certainsafety features and practices. Preventing the con-tamination of ground water is critical. Chemigationof some insecticides is prohibited because theyare highly toxic to mammals or ineffective whenapplied in irrigation water. Refer to the pesticidelabel to determine if chemigation is prohibited orif it is an approved application method. Currently,bifenthrin (Capture®), carbaryl (Sevin®), chlorpyri-fos (Lorsban®), dimethoate, permethrin (Ambush®

and Pounce®), esfenvalerate (Asana® XL), Lambda-cyhalothrin (Warrior®), methyl parathion (Penncap-M®) and spinosad (Tracer®) are registered forchemigation of corn in Texas. If approved forchemigation, the label will identify specific safetyequipment and procedures that are required byfederal law if the product is applied in this way.Refer to the product label for specific instructionsand restrictions regarding chemigation.

The label also may provide instructions for mix-ing, diluting and agitating the product and statethe quantity of irrigation water to be applied dur-ing chemigation. Certain additives may be recom-mended to increase pesticide efficacy by reducingwashoff. Irrigation systems with nozzles posi-tioned above the crop canopy should not be usedfor chemigation during windy weather because ofthe danger that pesticides may drift from the treat-ed field. Also, endguns should be shut off duringchemigation. Personal safety equipment should beworn during mixing and loading of the insecti-cide. Avoid contamination of the site with spilledpesticide, and properly dispose of pesticide con-tainers.

The pesticide injection pump unit must be care-fully maintained and calibrated to uniformly applythe insecticide at the desired rate in the irrigationwater. Inaccurate calibration can cause under-application, which reduces insecticide effective-ness, or over-application, which increases costs

and crop and environmental contamination. Referto the Texas Cooperative Extension publication,“Chemigation Workbook” (B-1652), available fromyour county Extension office, for additional infor-mation on calibration and chemigation.

Protecting Bees and OtherPollinators fromInsecticides

Pollination is extremely important in producingmany seed crops. This is particularly true forlegumes such as alfalfa, clovers and vetch. Mostgrass-type plants are wind or self-pollinated anddo not require insect pollinators. Where pollen-collecting insects are required for flower fertiliza-tion, the producer, insecticide applicator and bee-keeper should cooperate closely to minimize beelosses. The following guidelines will reduce beelosses:

• If practical, apply insecticides before bees aremoved into fields for pollination.

• Where insecticides are needed, use materialsleast toxic to bees.

• Make all applications when bees are awayfrom the field. Evening or early morningtreatments between the hours of 7 p.m. and6 a.m. generally are most satisfactory.Evening applications after bees have left thefield are less hazardous than early morningapplications.

• Use spray or granular formulations ratherthan dusts.

• When possible, use an insecticide in groups2 or 3 in the following list. Notify the bee-keeper so that he or she can make necessaryarrangements to protect the bees.

• Avoid drifting or spraying any insecticidedirectly on colonies. Heavy losses generallyoccur in these situations. On hot evenings,bees often cluster on the fronts of the hives.Pesticide drift or direct spray at this timeresults in heavy bee kill.

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Honey Bee Hazards

Insecticides Remarks

Group 1. Highly Toxic This group includes substances that kill bees onCarbaryl (Sevin®) contact during application and for several daysCarbofuran(Furadan®) following application. Remove bees from the

Chlorpyrifos (Lorsban®) area if these products are used on plants beingDimethoate visited by the bees (with some exceptions). Esfenvalerate (Asana® XL) Malathion occasionally causes heavy bee losses, Lambda-cyhalothrin (Warrior®) particularly during periods of extremely highMalathion (wettable powder or ULV) temperatures. Apply malathion in the eveningMethomyl (Lannate®) after all the bees have completed foraging. Avoid Methyl parathion (EC, Penncap-M®) ultra-low-volume malathion after blooms appear.Parathion Permethrin (Ambush®, Pounce®) Spinosad (Tracer®)

Group 2. Moderately Toxic Apply in late evening.Bifenthrin (Capture®)Disulfoton (Di-Syston®)Malathion (EC) Phorate (Thimet®)

Group 3. Relatively Non-Toxic Apply in late evening or early morning whenDipel® bees are not foraging.Sulfur Propargite (Comite )

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Appendix IInsect and Mite Pests

corn leaf aphid aphid mummies corn earworm adult corn earworm larva

chinch bugs Mexican corn rootwormadult

southern corn rootwormadult

corn rootworm larva

western corn rootwormadult

cutworm European corn borer larva fall armyworm adult

fall armyworm larva flea beetle lesser cornstalk borerlarva

Mexican rice borer larva

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Appendix I (cont.)Insect and Mite Pests

Banks grass mites Banks grass mite colony neotropical borer adult neotropical borer larva

sap beetle sugarcane borer adult sugarcane borer larva southwestern corn boreradult

southwestern corn borergirdle

southwestern corn borerlarva

white grubs wireworm larva

false wireworm yellowstriped armyworm western bean cutwormegg mass

western bean cutwormlarva

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Appendix IIBeneficial Arthropods

bigeyed bug green lacewing egg green lacewing larva lady beetle adult

lady beetle larva lady beetle pupa orius adult orius nymph

crab spider syrphid fly larva

Educational programs conducted by Texas Cooperative Extension serve people of all ages regardless of socioeconomic level, race,color, sex, religion, handicap or national origin.

Issued in furtherance of Cooperative Extension Work in Agriculture and Home Economics, Acts of Congress of May 8, 1914, asamended, and June 30, 1914, in cooperation with the United States Department of Agriculture. Edward Hiler, Director, TexasCooperative Extension, the Texas A&M University System.

2.5M, Revised

The information given herein is for educational purposes only.Reference to commercial products or trade names is made withthe understanding that no discrimination is intended and noendorsement by Texas Cooperative Extension is implied.

Produced by Agricultural Communications, The Texas A&M University System

Extension publications can be found on the Web at: http://texaserc.tamu.edu

Produced in part with funding fom the Texas Corn Producers Board

managing insect and mite pests of texas...

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