However, continuous corn production in the same field increases the likelihood of western corn rootworm infestations. In the case of smartstax pro, scientists harnessed rnai to create a pesticide that works by silencing or turningoff the activity of a gene critical to corn rootworm survival. Rotating corn hybrids that incorporate bt traits with nonbt corn treated with a soilapplied insecticide should be considered as a strategy to slow resistance evolution, especially in areas that are currently experiencing only moderate corn rootworm pressure. This publication summarizes integrated pest management of corn rootworms in field corn including identification, life cycle, crop damage, field scouting, thresholds, root injury ratings, cultural control, bt corn hybrids, biological and chemical control. For use only with smartbox closed handling application system. Corn rootworm management options using soil insecticides. The northern corn rootworm has shown extended diapause, in which eggs remain viable in the soil for several years before hatching. Role of 2,4dihydroxy7methoxy1,4benzoxazin3one dimboa in the resistance of maize to western corn rootworm, diabrotica virgifera virgifera leconte coleoptera. Apply in combination with 4 oz penncapm insecticide or other insecticides. Project methods laboratory bioassays will be developed to evaluate insecticide resistance in adult and larval western corn rootworm populations. The development of resistance to bt traits in the western corn rootworm is an ongoing problem, with. However, scouts and farmers have noticed rebounding populations of adult corn rootworm in the landscape now, especially noting root injury to firstyear corn by northern corn rootworm. Growers are encouraged to monitor cornfields for wcr and ncr adults to determine the need for a soil insecticide the following year if corn will be planted again in the field. Larval susceptibility of an insecticideresistant western.
Fieldevolved resistance to bt maize by western corn rootworm. Western and northern corn rootworm adults page 53, corn. May also be applied as a tband with incorporation into the top oneinch of soil. Scientists have engineered the corn plant so that when the corn rootworm feeds on the plant.
However, epa believes that other parts of the corn belt, where corn rootworm infestations are common and the use of bt corn is high, are also at risk for resistance. Corn rootworms pests corn integrated pest management. The crw bt protein, on the other hand, is a low dose insecticidal protein. Resistance to bt corn by western corn rootworm coleoptera.
Using multiple modes of action for crw control like genss, available as wyffels rib, provides more consistent control and reduces the chances of insect resistance developing. Until this past year bifenthrin insecticide has been used almost exclusively for both soil applications and beetle sprays. Western corn rootworm pyrethroid resistance confirmed by. Western corn rootworm resistance to plant incorporated bt proteins gmo hybrids has refocused attention. The soybean variant western corn rootworm has evolved to lay eggs in noncorn fields. Thus, it is crucial to develop a better insect resistance management irm strategy that will delay the rate of btresistance evolution and maintain the effectiveness of bt corn. In addition, an insecticide applied at planting may improve control and reduce the risk of economic root damage when insect pressure is very. Widespread planting of bt corn places intense selection pressure on target insects to develop resistance, and evolution of resistance threatens to erode benefits associated with bt corn, such as. This is due, in part, to exceptionally wet spring conditions in 2014. In parts of iowa and south dakota, the northern corn rootworm has. Subsequent bioassays revealed cry3bb1 resistance in these. Some newer trait packages require a smaller refuge of nonbt corn.
Also sample corn fields that were in other crops like soybean the previous season, if beetles were observed or suspected as being present in those crops the previous year. The treatment threshold that are used for the protection of corn silks and decreasing the potential amount of eggs laid may be different. Gauge next years crw larval threat based on this years beetle numbers. Bt resistance is especially dangerous in the parts of the corn belt that have a population of western corn rootworm that survives crop rotation by laying eggs in soybean fields. Western corn rootworm is a key pest of maize, and in continuous maize fields it is often managed through planting of bt maize. When economic threshold levels are reached, adult management of corn rootworm beetles may help protect yield potential for the current crop as well as decrease the amount of eggs deposited. Framework to delay corn rootworm resistance regulation. Evolution of resistance to bt corn by western corn. Corn rootworm management recommendations monitoring corn fields for corn rootworm crw beetles can help determine crw pressure in the subsequent year. Western corn rootworm leave corn field to lay eggs in soybean or other crop fields. Corn rootworm damages corn plants growing in the field by eating the roots.
Resistance management guidelines for bt corn require a producer to plant a refuge of nonbt corn. Control may not always be optimal in op resistance areas if invite is tankmixed with methyl parathion or carbaryl. Rotation not only eliminates that rootworm population the following season, but it has many agronomic benefits. Bruce eisley, integrated pest management research associate. Corn rootworm beetle management background the annual economic loss to corn belt farmers from corn rootworm crw activity has been estimated to be at least one. Crop rotation will almost always eliminate corn rootworm. Western corn rootworm resistance and control concerns. Northern corn rootworm numbers jumped dramatically in illinois in 2018 based on the statewide survey for that insect, though they dropped considerably in 2019 table 2. It takes a larger amount of feeding before corn rootworm larva is controlled.
Northern corn rootworm extend its egg diapause from one year to 15 years. Consider a foliar spray if adult populations feeding on silks exceed 10 per plant. Where continuous sweet corn is grown, or if sweet corn is planted after field corn, treat all seed with a rootworm insecticide. Lastly, the southern corn rootworm has a green body that is easy to distinguish because of the black spots on its back. They modeled six alternative irm strategies over a 15year time horizon table 7. Transgenic bt corn hybrids that produce insecticidal proteins from the bacterium bacillus thuringiensis berliner have become the standard insect management tactic across the u. Periodic crop rotation out of corn can greatly reduce rootworm populations. Pdf nf99367 adult western corn rootworm insecticide. Managing western corn rootworm resistance to bt on the. Adults feed on corn silk, leaves and pollen of numerous plants including corn. Do not apply as a surface band behind the press wheel. Western corn rootworm adults will be collected from various locations across nebraska and other midwestern states for use in lab bioassays and to document the degree of insecticide resistance across the region.
Invite ec contains cucurbitacin, a corn rootworm specific feeding stimulantarrestant. For corn borer, only a nonbt insecticide may be used in the refuge if targeted insects reach. If soil applied insecticides have been used continuously when planting bt rootworm corn hybrids and spraying for beetles, the rootworms could also have developed resistance to the insecticides. Xie ys, arnason jt, philogene bjr, lambert jdh, atkinson j, morand p, 1990. Corn rootworm management has become complex as the pests ability to evolve has made crop rotation ineffective in many areas. The male rootworm from this type is usually smaller and darker. Alan sundermeier, agriculture and natural resources extension agent. These reports either show some crw resistance developing iowa report or at least severe root damage present on bt hybrids that are used to control feeding larva illinois report. Highlights from migration lecture university of arizona. Having demonstrated the need for corn soil insecticides, amvac offers four products for growers depending on their individual needs. Strategies for managing corn rootworm problems in rotated. The western corn rootworm, diabrotica virgifera virgifera, is one of the most devastating corn rootworm species in north america, especially in the midwestern corngrowing areas such as iowa. For a second year in a row, corn rootworm abundance is lower than expected in iowa.
University extension entomologists report that fieldbased western corn rootworm crw resistance to the bt toxin cry3bb1 is now found in four states, with confirmation announced recently in. Pros and cons of soil insecticide use for corn rootworm. Use invite with caution in areas where adult corn rootworm organophosphate op resistance has been documented. Dosagemortality curves and ld 50 values were determined for each insecticide. Extension entomologists recommend the following procedure for monitoring wcr and ncr beetles. It is not too early to make management decisions for next. Beginning in 2003, bt maize was commercialized for control of western corn rootworm larvae and was rapidly adopted by farmers, constituting over 45% of maize crop in the united states during 2009. Avoid repeated use of the same insecticide products and bt corn proteins to avoid development of resistance, and maintain efficacy of these important management tools. The use of diverse management tactics on a farm is the best strategy to manage rootworms.
The northern corn rootworm, on the other hand, has a green to yellow body and the female is usually the one that is larger. Wright rj1, scharf me, meinke lj, zhou x, siegfried bd, chandler ld. Western corn rootworm an overview sciencedirect topics. Adult control for the purpose of protecting a silking ear may not be the same as beetle control for future population. Diabrotica virgifera virgifera western corn rootworm. Adult wcr are gold in color with a black head and three black stripes on wing covers. Epa registers innovative tool to control corn rootworm. Increase the rate to control higher rootworm populations.
Fieldevolved resistance by western corn rootworm to. Corn rootworm management update cropwatch university. Integrated pest management of corn rootworms in north. Corn rootworm management update integrated crop management. Insecticide resistance in the adult western corn rootworm. If you plant continuous corn, make it a point to rotate fields on a schedule every 3 to 4 years. Only a small amount of feeding is required to control corn borer larva, so control is relatively consistent and effective.
In the case of male wcr, the black stripes often merge to the point that the entire wing cover appears black. However, the evolution of resistance by the western corn rootworm could cut short the benefits of bt maize. Insecticide recommendations for corn root worm cropwatch. These areas are known as the corn rootworm red zone and include portions of iowa, illinois, nebraska, western indiana, southwestern wisconsin, southern minnesota, and eastern. Objective to evaluate corn response to soil rootworm insecticides in a field following soybeans.
Managing suspected western corn rootworm resistance in bt corn keep crop rotation in your system. Read more regional news about agriculture and crop production on agweb. Sample those corn fields with suspected insecticide failures or fields in which a high adult rootworm population was observed, the previous julyaugust. Larval susceptibility of an insecticideresistant western corn rootworm coleoptera. In parts of illinois, indiana, and ohio, the western corn rootworm developed a soybean biotype that leaves corn fields to lay its eggs in other crops, rendering crop rotation ineffective. In the western corn belt, wcr resistance evolution to rootwormactive bt traits has increased the importance of aeriallyapplied insecticides and crop rotation as. The fieldevolved resistance to multiple bt traits by western corn rootworm has threatened the effectiveness of bt technology. We have learned several important characteristics of western corn rootworm crw control from recent reports of severe rootworm feeding on bt hybrids. Corn rootworm insecticide comparison ohio state university. Insecticide treatments for corn rootworm larvae in field. During 2009 and 2010, field s were identified in iowa in which western corn rootworm imposed s evere injury to maize producing bt toxin cry3bb1. Western corn belt, western corn rootworm has developed resistance to several insecticides. Nf99367 adult western corn rootworm insecticide resistance in nebraska.
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