Diagnosing

CORNPRODUCTIONPROBLEMS

in Kansas

Kansas Corn CommissionKansas State Board of Agriculture

Cooperative Extension ServiceKansas State University, Manhattan

orn, like all crops,Cmay suffer from a variety of insect,

disease, nutritional, and

environmental stresses

This publication will help in

diagnosing likely causes of slow

growth, distorted appearance,

off-colors, injury, and death of

corn plants from planting

through harvest.

Problems During Stage I:Planting toThree Leaves Fully Emerged

Problems During Stage II:Four-Leaf Stage to Silking

Problems During Stage III:Silking toPhysiological Maturity

Careful inspection of plants, soil, and the generalfield situation is necessary in problem solving. Todo the job right, you need some basic equipment,such as a short-handled shovel or spade, soil probe,pocket knife, razor blade, hand lens or magnifyingglass, pencil, notebook, small bottles with andwithout alcohol, and an assortment of plastic bags.

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Frequent field inspections are required during theperiod of stand establishment. This requirementcannot be overstressed because, in most instances,accurate diagnosis of problems is more likely if thefields are inspected when the symptoms are readilyvisible. Delayed inspections usually result in fewerpositive answers, in part, because fewer clues remainto guide the investigation.

Poor seedling emergence is the first problem com-monly encountered following planting. Take time toexamine the evidence. Look for patterns. Is thestand uniformly poor? Are there skips? Are therestunted or dying plants? What are some of thecauses that may lead to poor stands? Consider theoverall pattern of injury along with the recent historyof the field. Close examination of the situation willhelp to determine the actual cause or causes of poorstands. 4

A uniform patternof skipsin dry soil suggestsa clogged, jammed,or broken planter.This photographdepicts a situationwhere seed wasplaced at unevendepths in dry soil.Dry soil does notencourage quickand even germina-tion.

This field has anuneven plantpopulation, with a holein every spot where aseed was placed.

Notice that there is an empty seed coat in the bottomof one hole. Rodent damage is suspected becausesoil is piled up to one side of the hole. Look forburrows along field edges to help confirm the cause.

Several insects attack planted seed, destroying the germor feeding on the germinating tissue. When cool tem-peratures delay germination, the risk of damage in-creases as the seed is exposed to a longer feeding periodby insects.

Seed corn beetles aresmall dark-browninsects often observedin the soil surroundingplanted seed. Searcharound the area,moving clods, and lookfor these active beetlesscurrying around in thearea.

The seed corn maggot is another insect that attacksplanted seed. Maggots or immature stages of thissmall fly can cause fieldwide problems. Frequently,several of the carrot-shaped maggots will be foundfeeding on each infested seed. Often, this problemoccurs when the soil is high on supplemented organicmatter. Problems in Kansas occur most often wherelarge amounts of cattle or swine manure have beenspread over the field or where alfalfa or brome hasbeen turned under before the field was planted.

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Seedlings sometimes become malformed when they cannotpush through the soil surface crust. Here the seeds germi-nated, but the seedlings grew sideways and were unable toemerge. Driving rains or planting in too wet soil can causecrusting problems.

When you notice plants that emerged in good shape laterdie or are looking poorly in isolated or widespread areas ofthe field, it is time to suspect root damage. The stand maybe spotty, with some plants wilting and lodging. Fre-quently, there is no obvious above-ground injury. It’s timeto use the shovel to dig up some plants. Look for insects inthe plant’s root zone. See enlargement of insect below.

These hard-bodied, yellow-brown, wire-like insects arewireworms. The wilting is a result of wireworms pruningroots and burrowing in the base of the plant. Wirewormsalso will feed on germinating seed and are more frequentlyfound where some type of grass vegetation has been torn upto plant corn.

Yellowed, wilted plants in poorly drained or com-pacted areas of affected fields are sometimes ob-served. Typically, the stem tissue near ground levelpossesses discolored, water-soaked areas. Collec-tively, these symptoms indicate that seedling blightinjury has occurred.

This photograph shows a different type of insectdamage. Small transparent areas on the leavesindicate where feeding has occurred. This “win-dow feeding” caused by young black cutwormsoften is overlooked.

“Window feeding” is caused by small black cutwormlarvae or related species. Older larvae cut plantsnear the soil surface. Damage may be heavy in someareas of the field and minimal in others. Cutwormsfeed at night and hide underground during the day.The mature larva is a plump, smooth, greasy-lookingdark gray, spotted, or striped caterpillar.

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Plants in this field have a bleached and stunted appear-ance. Command herbicide was applied to the previousseason’s crop of soybeans and carryover effects are nowquite evident.

The stunted and chlorotic (yellow) plants in this field wereinjured by Pursuit herbicide, applied before plantingimidazolinnone-susceptible corn hybrids.

Early injury from flea beetles appears as scratches on thetop leaf surface. Now the plant leaves are shriveled, grayand dead.

These stunted plants were caused by the herbicideScepter, carried over from the previous year’sapplication to soybeans. There may be a pattern inthe field where the herbicide application overlapped(was doubled) or where differences occur in soilmoisture.

The bottle-brush appearance of these roots resultedfrom very severe Tri-Scept (trifluralin and Scepter)carryover.

These plants are stunted and doing poorly where theClassic herbicide component in Canopy carried overfrom the preceding soybean crop. Classic carryover isgreater in dry years and in high pH soils. In thisinstance, the high pH was caused by poor incorpora-tion of lime.

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These plants were damaged by flea beetles. Plants aremore susceptible to injury when temperatures were coldand seedling growth slow. Plants often are able to recoverfrom flea beetle injury because the growing point remainsbelow ground level until about the time that the fifth leafemerges.

In diagnosing crop production problems, compare astressed plant with a healthy plant whenever possible.Notice the plant on the right is stunted. Plants alsocould be wilted or lodged. Small areas within the fieldare affected. There are no above-ground indications ofthe cause which means the problem may be originatingunderground.

Careful digging in thecrop row where plantsstarted wilting afteremerging normallyrevealed white C-shapedgrubs pruning the rootsin this situation. An-other sign that whitegrubs may be present inhigh numbers is anumber of plants exca-vated by rodents lookingfor insects.

The leaves on these corn plants first appearedwatersoaked, then turned white within a few days offreezing temperatures. Damage may be restricted tolow-lying areas or may be fieldwide.

A late freeze will kill leaves. Plants damaged to thisextent could recover because the growing point is stillunderground. Survival may be determined by thefavorability of post-freeze weather condition.

Less severe frost damage is shown here. Think about clues thatwould help separate these symptoms from anhydrous ammoniafertilizer. Wheel tracks from the applicator may still be present.Anhydrous ammonia also tends to injure the roots, especially onthe side of the row next to the knife, whereas freeze-damagedplants typically have healthy, intact roots.12 13

The leaves on these plants have dead margins and are not fullyexpanded. Their roots appear sheared off or dried up. Also,note the tire tracks left next to the row by equipment recentlypassing through the field. This type of injury and the corre-sponding wheel tracks suggests fertilizer burn. Free ammonia,capable of producing this injury, is most likely to be presentwhen side-dressing of fertilizer occurs under dry soil condi-tions. Plants often will recover from this type of injury.

Soil caked in the whorl of the plant is a reliableindication that this portion of the field experiencedsome high water caused by localized flooding.

The corn in this photograph emerged to form a goodstand, but there are discolored leaves and/or stems.The damage may be in isolated or widespread areasof the field. Phosphorus deficiency can causeseedling plants to discolor in this manner.

As stated in the previous explanation, stunted growth andpurple leaves early in the growing season are symptoms ofphosphorus deficiency. This condition can be caused bypoor soil phosphorus availability, which is enhanced bycool, wet growing conditions. A soil fertility test is one ofthe most definitive tools used to confirm this situation.

Young corn plants with root damage (inhibited rootgrowth) caused by Treflan herbicide carryover often showsymptoms of phosphorus deficiency. Note the purple colorof the stunted plant on the left.

Leaves on these plants are emerging abnormally, in amanner often described as onion-leafing. In this example,injury was caused by the herbicide Sutan. Realize,though, that similar symptoms can be induced by 2,4-D.

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During this stageof development,corn plants aredeveloping rapidly.Leaf area is beingformed, the stalk iselongating, andtassel and eardevelopment isstarted. A varietyof problems maybe encounteredduring this stage ofcorn development.

Plants are wilted and stressed. Problems are usually firstnoticeable in the 20 to 30 rows along the field margins,especially near fields of ripening grain. Chinch bugs,more typically thought of as problems for young sor-ghum, may cause corn plants to respond by wilting.

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The small black bugs clustered near the base of the plantare chinch bugs. Adults are tiny insects with a blackbody and white wings. Nymphs are red with a whitestripe across the body and are wingless. Nymphs andadults feed on the stalk from somewhat above the soilsurface to just below it.

The problem represented in this photograph is droughtstress. Plants needing water appear dull. The upperleaves roll upward and inward.

This corn plant showssymptoms of Accentor Beacon injury.The plant is stuntedbecause of poorinternode elongation.Wrinkled leavessuggest disruption ofcell elongation.

Spray drift from application of soybean herbicidessuch as Assure, Fusilade, and Poast may severelyinjure corn. Check surroundings for sources of drift.Shattercane growing with the corn should die morequickly than the corn if Accent or Beacon caused theinjury. Should shattercane and corn show similarsymptoms, suspect Assure, Fusilade, or Poast injury.

These plants have lodged. 2,4-D often causes temporarystalk brittleness in rapidly growing plants, making themsusceptible to wind or cultivation damage. Plants brokenoff at the base will die. Noting that nearby broadleafweeds are curling and twisting also helps diagnose 2,4-Das the cause of this problem rather than injury caused bycorn rootworm larvae.

As lodged plants continue growth, they curve upwardresulting in the goosenecking seen here. Note therighthand plant is slightly bent and the center plantshows more severe symptoms.

Corn leaf collars (whereleaf wraps around stem)may be mildly chlorotic,perhaps caused by cool,wet weather followingAccent or Beaconapplication. Weatherconditions that reducecorn metabolism alsolower the capability ofthe plant to withstandthese herbicides.

Sometimes, weakenedleaf whorls twist andbend over, especially inhigh winds in highwinds. Cold weather,poor soil aeration, andinteraction with certainsoil insecticides all cancontribute to reducedcorn metabolism.

Accent and Beacon arefoliar-applied herbicidesthat translocate to thegrowing points of theplant. This plant illus-trates numerous symp-toms, including poorinternode elongation,chlorotic leaf collar,wrinkled leaves, and adistorted whorl.

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Another symptom of 2,4-D injury is the mild leaf rollingseen in plants on the right. Check soil moisture andsymptoms on broadleaf weeds to distinguish betweendrought effects and 2,4-D damage.

Sometimes 2,4-D, Eradicane, Sutan, and evenLasso or Dual cause leaves to roll up tightly into awhip-like form.

Brace roots maybecome fused andtwisted after exposureto 2,4-D. This can belargely avoided byearly cultivation tothrow untreated soilinto the corn row tocover the lower nodes,before 2,4-D applica-tion.

Occasionally, herbicideswill inhibit root growth andlimit the amount ofphosphorus that plants cantake up. This results ininjury symptoms similar tophosphorus deficiency.This field was treated withCanopy herbicide last yearwhen it was planted tosoybeans, and now thecorn is showing carryoversymptoms.

Plants with shredded, bruised and broken leaves, stems,and leaf midribs are present everywhere. Hail and highwinds have caused this fieldwide damage. Hail-damagedplants often have a deformed appearance. Realize thatdamaged plants can fully recover from this injury if itoccurs before the eight-leaf stage.

All the leaf tissue has been removed from these plants withthe exception of the midrib. Feeding progressed upward, anddamaged plants were most commonly found on the edge ofthe field. Armyworms moving in from drying, small grain-fields or from lush, grassy areas are to blame.

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Severe leaf bladeremoval withoutaffecting midribs ischaracteristic ofheavy armywormfeeding. Thearmyworm can berecognized by itsgreenish-black bodywith dark andorange-striped sidesand a white stripe onits back.

It looks as if an insecthas been feeding in thewhorl of this corn,creating a type ofdamage often referredto as ragworm injury.Corn earworms are arelatively commoninsect, capable ofcausing this injury.Many times, the wormwill mature and leavebefore the damage isnoticed.

One form of damage caused by European corn borer larvaeappears as rows of shotholes when leaves unfurl. Europeancorn borers chewing through developing leaves leads to thischaracteristic type of damage.

Older European cornborer larvae tunnel inmidribs of leaves.Once weakened, themidrib often breaks atthe injured point,allowing the tip of theleaf blade to drop,limiting its usefulnessin gathering sunlight.

Stunted and excessively tillered plants, usually locatednear the edge of the field, are encountered occasion-ally. Insects killing the growing point can lead to thedevelopment of this condition, described as deadheart.

The deadheart injury inthis example wascaused by commonstalk borer (or simply“stalk borer”) feedingon the corn plant’sgrowing point, butsimilar injury can becaused by any stalk-boring insect. Commonstalk borer is easilyrecognized by thetransverse purple bandoccurring near the legs.

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The lower leaves on these plants have margins that areyellowing and dying, which indicates a soil fertilityproblem--potassium deficiency. Compacted soilscontribute to this problem. The condition also candevelop where there was a heavy demand for potassiumby the previous crop, for example, alfalfa. Regular soiltests and a fertility program can prevent this problem inthe future.

Compacted soil can induce stunting, abnormal rootgrowth, and nutrient deficiencies. Note the row ofstunted plants growing next to a row of normal plants.

These stems have a “gooseneck” appearance. Theplants apparently fell over earlier in the season, thenrecovered as time passed. This could have been causedby wind, possibly combined with brittleness of the stemsfollowing foliar applications of 2,4-D or Banvel herbi-cides. Or, it could be caused by problems with the rootsystem, so look below the soil surface to diagnose thecause of this problem.

Believe it or not, the plants in this slide are thesame age. In this instance, the severe stuntingwas caused by the Treflan carryover from theprevious cropping season. Notice the uni-formly short, club-shaped roots. Treflaninterferes with cell division and elongation.

Corn rootworm larvae can destroy most of a plant’sroot system, leading to lodged plants and gooseneckappearances. Affected roots appear brown, andtunnels occur in the larger roots.

This photograph shows a mature rootworm larvafeeding on corn tissue. These insects are aboutone-half inch long, slender, and white, with a brownhead capsule and plate at the rear, which makethem appear to be “two-headed.”

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Several species of rootworm are found in Kansas.This is a picture of an adult southern corn root-worm beetle feeding on a leaf. Adult feedingresults in scratches and small holes. The bottomleaves on a plant may die if the infestation issevere.

Compare the southern corn rootworm adult with thispicture of an adult western corn rootworm beetle.The western corn rootworm is by far the morecommon rootworm species in Kansas. Rootwormadults also feed on pollen and silks.

Plant growth across this sandy field is uneven andthere are circular or elliptical patches of stunted,chlorotic plants. Nutrient deficiencies are ruled outthrough soil fertility testing, and the pattern is notconsistent with herbicide misapplication or carryover.Nematode injury still remains a viable option.

In comparing these two rows of corn, you willnotice that the plants in the foreground are severelystunted. There is no above-ground indication thatnematodes are causing these problems.

A bucket of water will help wash the soil from the roots. Noticetheir stubby, stunted appearance--which might be herbicide injury ora nutrient deficiency; however, the stubbiness is too localized on theroot system to be a herbicide injury. A soil test confirms stingnematodes, microscopic worm-like organisms living in soil and planttissue. Less common nematodes cause similar above-groundsymptoms on corn. Annual soil tests through county agents willhelp determine management strategies.

Brace roots on this corn plant are short, fat, and stubby.They failed to develop properly after coming in contact withsoil treated with a late post-emerge application of Treflan orProwl. Note that the deeper roots (below the treated soil) arenormal and only the shallowest of roots are affected.

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As corn approaches maturity, grain is forming and filling. Anumber of problems can reduce potential yields. Correctdiagnosis is still the key to selecting among available manage-ment strategies for the approach that will solve the problems.

This problem is easyto diagnose. Thedamage is field-wide.Stalks are bruised andmidribs are broken.There are dark bruiseson the husks, and theleaves are shredded.Damage often is moresevere on one side ofthe plants. Thisinjury was caused byhail and high winds.

When hail is severe, corn ears can be damaged. Haildamage also contributes to infection by stalk rots, earrots, and smut.

Large chunks of tissue have been removed from themargins of these leaves, giving them a ragged appearance.Hail is ruled out, because stems are not bruised, fewmidribs are broken, and damage is mostly confined tofield margins. Insects such as grasshoppers should besuspected.

Grasshoppers havebeen moving out of theweedy borders into thisfield to feed on cornplants. Grasshoppersalso prune silks andfeed on leaf sheaths.

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These plants werestripped of leaf tissue,except for midribs.Damage began at thebase of the plant andprogressed upward.Feeding is most notice-able at field margins orwhere grass herbicidefailed. Lush grassesattracted egg-layingadults. Larvae move tocorn as the grass inconsumed. The injury iscaused by large numbersof armyworm.

This problem is almost always associated with hot,dry weather and is most common in western Kansas,with occasional fields in the north central area,particularly Republic County, showing similar prob-lems. Initially, the injury appears as tiny yellow orwhite spots on the upper leaf surface. Look at theentire plant to determine if spider mites are involved.

Look at the patternof damage on thisplant. Damage tendsto be on the lowerleaves andprogresses up theplant, typical ofspider mite infesta-tions. Mite popula-tions tend to beheaviest along theleaf midribs. Theunderside may havelight webbing andhundreds of mites,which appear as tinycrawling specksunder a hand lens.

A variety of diseases cause discoloration of leaf tissue.Most corn growers recognize this disease as common rust.Above-ground portions of the plant have cinnamon brownblisters on them.

Southern rust symptoms are similar to those of commonrust, except blisters appear on upper leaf surfaces only.Again, the blisters are full of a powdery material thatwill rub off on hands and clothes.

This disease affects the youngest leaves of a corn plant, with amosaic pattern of light and dark green. This spotting developsinto light green and yellow streaks along the leaf veins. Thesesymptoms are characteristic of maize dwarf mosaic, which iscaused by a virus. Symptoms are often difficult to discern,because frequently the mottling is not readily apparent. In-fected plants may be slightly stunted, with ear set and ear sizereduced.

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Corn lethal necrosis is a disease resulting from theinteraction of maize dwarf mosaic virus and maizechlorotic mottle virus. The symptoms are severe yellowmottling, followed by browning of leaves and earlydeath of plants. Death begins at the tassel andprogresses downward.

This soil fertilityproblem reflects nitro-gen deficiency showingup late in the growingseason. Note the V-shaped yellowing alongthe midrib on thebottom leaves. Thestalks are thin andspindly, and the earsappear pinched, withflinty kernels. At thispoint, it’s too late forcorrective nitrogenapplication.

These stunted plants exhibit an interveinal striping andare suffering from magnesium deficiency.

Magnesium deficiency can be caused by compacted soil,although sandy soils low in organic matter may alsocontribute to these problems.

Small, blue-green, soft-bodied insects have coated the tasseland upper portion of this plant. The plant also is coveredwith a sticky substance, and numerous white cast skins areseen on the plant and on the ground around the plant. Theleaves appear wilted, curl, and show yellow patches. Thedistribution of affected plants in the field is spotty. Lookclosely for corn leaf aphids on plants with these symptoms.

These insects are corn leaf aphids. Note the prominent,dark blue “tail pipes” on the aphid. White cast skins alsoare seen on the leaf. Upper leaves and tassels of cornplants may be densely colonized. Aphid colonies release asticky substance that may coat nearby plant parts. This“honeydew” sometimes takes on a blackened appearanceas microorganisms use it as a food source.

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Symptoms of crazy topdowny mildew includerolling and twisting ofthe upper leaves and atassel or ear thatresembles a mass ofleafy structures. Theplants were infectedearly in the growingseason, when the soilwas water-saturated for24 to 48 hours.

These tassels have galls covered by silvery membranes,enclosing a black and dusty interior. The disease iscalled smut and a trace of it usually is found in everyfield. Prevalence of smut is usually greatest after thefield experiences hail damage or stress caused by wind-blown sand. Some hybrids are more susceptible thanothers.

Smut also can infect ears. It’s the infected kernels thatenlarge and form silvery galls.

When corn earworms feed on kernels, usually at firstnear the ear tip, they open the husks and provide anentry for disease and bird feeding. Larvae vary incolor from brown to green to purple. The larvae haveyellow lateral stripes and very tiny spines on raisedbumps. Because larvae are cannibalistic often just afew of them are left on an infested plant.

Other insects also can produce insect-damaged ears.For instance, western bean cutworm larvae enter earsthrough tips or chew through husks.

Western bean cutworm feeds on kernels. Feeding onsmall ears can cause ear deformation.

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Poorly filled ears can result from a number of rea-sons including high numbers of corn rootwormbeetles feeding on the silks, excessive heat, and dryweather.

Corn lethal necrosis-infected plants may not produce ears.If ears are produced, the seed is shriveled and the ears areseverely rotted. Symptoms sometimes mimic damagecaused by Eradicane.

Excess heat during the pollination period causedsterility and poor seed set on these plants. Hot, drywinds during pollination can increase the severity ofthis problem.

When insects, like these Northern corn rootwormbeetles, feed on silks and clip them off, the result canbe incomplete pollination. Grasshoppers can alsoclip silks. Silk clipping has to be severe, though, toprevent or limit pollination.

Dry weather can slowsilking and tasselingto the point of caus-ing poorly filled ears.These plants havegreen silks, but thepollen has alreadyshed, resulting inlimited pollination.

Ears sometimes become malformed after misapplica-tion of a herbicide--in this case Eradicane. Thetwisted and wrinkled leaves visible at the base of theears indicate an unthrifty, sick plant.

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During the normal growth and development of corn, thenumber of potential kernel rows doubles at the V9stage, producing ears with even numbers of kernel rows.This doubling may be inhibited when Accent or Beaconis applied late and can result in the “pinched” appear-ance to the ears of affected plants.

Most of the stalks in this photograph have lodge d orbroken over in the middle. Note that some ears are lyingon the ground. Closer examiniation of the stalks isrequired to narrow the list of causes.

Insect damage is noticeable inside the stalk with tunnelspresent at the breaking point. European corn borer larvaeriddled and weakened the stalk with tunnels.

Mature European corn borer larva possess a dirty whitebody color and are covered with rows of slate-grayspots on the sides of the body. This caterpillar also hasa dark, mahogany-brown head. In addition to feedingin the stalk, larvae tunnel in ear shanks, causing theshanks to break and ears to drop to the ground.

In this lodging example, the stalks have lodged at thebase of the plant. Splitting the stalk open will benecessary to confirm that the culprit is southwesterncorn borer and not stalk rot. Fields with heavy infesta-tions should be given an early harvest priority or theymay become impossible to harvest.

Notice how this plant has been girdled. A majorchamber inside the base of the plant has been exca-vated, leaving only a small zone of attachment to holdthe plant intact. Splitting open the stalk reveals anextensive series of tunnels extending from the ear zoneto the base of the plant.

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Southwestern corn borer larvae have tunneled in stalks,girdling the bases. The larvae are white with black spotsdown the sides and an orange head capsule.

These stalks have lodged below the soil surface. Leavesare dull, and the lower internodes have softened. See thesubsequent photograph and text for more informationneeded to confirm that stalk rot is indeed the cause.

Dig up some plants and wash the soil from the roots. Itshould be evident that the roots are rotting and unable tosupport the plant, characteristics of root rot or stalk rot.

This is an example ofstalk rot. The pink/reddiscoloration of pithindicates fusarium stalkrot. When the stalks aresplit, symptoms are morereadily seen. The pitshreds or deteriorates andgrain may ripen prema-turely.

Notice the inside of this plant has a charred appearancefrom the numerous black fruiting bodies. Infected stalksshred and lodge.

This picture shows aclose-up of the blackfruiting bodies(sclerotia) of charcoalrot.

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Various colored molds or fungi frequently grow on and be-tween kernels. Some of these molds can produce toxins suchas aflatoxin, which can cause entire loads of grain to berejected. In the situation pictured, the grain is mature andrainfall has been above normal. Ear rots will be most prevalentfollowing ear injury from hail or insects, or from culturalconditions such as the ear not ripening in a downward position.

With this publication, you have had an opportunity to view anddiagnose several general types of problems that are associatedwith corn production. Your County Extension Agent can helpyou if you need additional information, a schedule of upcomingeducational meetings and tours, or assistance in diagnosingtroublesome problems.

You will find additional reference information on this topic inthese Kansas State University publications:Insect Management for Corn (for the current year), MF-810;Corn Production Handbook, C-560; and Chemical WeedControl for Field Crops, Pastures, Rangeland, and Cropland(for current year); and the Kansas Agricultural ExperimentStation Report of Progress.

Photographs used in this publication were provided by Exten-sion and research workers located within Kansas and acrossthe country. Special thanks are offered to the following peoplefor helping us complete this series:

Photographer Photo Numbers

D. Fjell 43D. Mock 7,8,9,51,74,75,85,102,113S. Race 14,15,21,50,55,56,105G .Wilde 23E. Nilson 33,45,47,108,110D. Gates 36,86,103L. Claflin 57,68,89,92,99L. Bonczkowski 71,73,109L. Moshier 80P. Sloderbeck 77,78,87,114K. Steffey 96,97G. Lippert 101Clemson Extension Service 121

Reference to specific products in this publication does notimply endorsement by the authors of Kansas State Univer-sity.

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Mary Moultonformer Extension Assistant

James P. ShroyerExtension Agronomy

Randall A. HigginsExtension State Leader, Entomology

Douglas J. JardineExtension State Leader, Plant Pathology

This publication was made possibleby a grant from the Kansas Corn Commission,

Kansas State Board of Agriculture.

Ray E. LamondExtension Agronomy

Cooperative Extension ServiceKansas State UniversityManhattan, Kansas

S-54 May 1993Issued in furtherance of Cooperative Extension Work, acts of May 8 and June30, 1914, as amended. Kansas State University, County Extension Councils,and United States Department of Agriculture Cooperating, Richard D.Wootton, Associate Director. All educational programs and materialsavailable without discrimination on the basis of race, color, national origin,sex, age, or disability.

File Code: Entomology 2, Plant Pathology 1-2, Crops and Soils 1-5. 5-93-2M

David L. RegehrExtension Agronomy