CRP-5

Cooperative Extension Service
Purdue University
West Lafayette, IN 47907

Not every situation will have insect problems. But be vigilant and prepared.

Insect problems can be serious threats to crops on land that has been in the Conservation Reserve Program for 10 years. Threats can be greater for some crops than others. Producers need to determine what insects and density of their populations are on those CRP acres and applicable control measures. Not every situation will have insect problems. But be vigilant and prepared.

Crop management and/or production choices for CRP land leaving the current program will impact insect control needs.

• Land placed back into CRP-There probably will be new pest management rules for land retained in a possible new version of CRP in the 1995 Farm Bill.

• Recreation and wildlife-Insect pest management generally will not be a consideration in CRP land converted to wildlife habitat and recreational use. Tick or mosquito control or protection of wildlife food plots may be desired, however.

Pest Problems in Hay

There can be problems from several pests damaging hay crops. They include:

• Alfalfa weevil-It usually is not a significant problem during the first few years following establishment.

• Potato leaf hopper This pest can cause considerable damage to new stands in mid- to late-summer. Risks are low in early spring and fall.

• Grasshoppers-They usually are associated with dry conditions and minimal soil disturbance. Drought is the most important factor. Outbreaks are easily managed with insecticides.

• Blister beetles and aphids Fortunately, these insects are not a common problem. But it is advisable to sample green forage for these and other insects when outbreaks occur or when something odd is present.

Pasture Problems Small

Insects rarely damage pastures more than livestock but outbreaks of Japanese beetle can occur. Use liquid insecticide formulations to lessen bird mortality.

Grasshoppers (in dry years) and army-worms may compete with livestock. But these insects are associated with environmental conditions that favor their survival. Suggested controls include acephate and carbaryl.

Corn's Enemies Numerous

Insects to watch for in corn following CRP include:

• Rootworm beetles-They and their larvae are not a problem in the first year. Rotation to another crop the following year is the preferred management technique.

• Wireworms-Long periods in which soil is undisturbed favor wireworms, the larvae of click beetles. Bait stations should be used to assess risks on a field-by-field basis. Treat corn with soil insecticide if an average of one or more wireworms is found per bait station.

• White grubs-The larvae of Japanese beetles, May beetles, or masked chafers, white grubs build to damaging levels under sod. The longer a field is in grass, the higher the infestation risk.

Sampling methods and thresholds have not been established for white grub control. Generally, treat corn with a soil insecticide if adult beetles have been abundant in the field in previous years. Do this, particularly, if smartweed and velvet leaf have been common weeds and a preplant investigation reveals about one larvae per square foot.

Low- or no-tillage and high- residue situations make a rescue treatment for corn difficult, if not impossible.

• Seed corn maggot-This pest can be a problem any time foliage is tilled into the soil to decompose. Wet weather coupled with matted, decomposing plants increases risk of this insect. Seed treatments are the most economical management option.

• Black cutworm-Damage from this pest is primarily dependent on spring weather and weed management.

• Stalk borer-Not to be confused with the European corn borer, its numbers are affected by previous years' weed types, such as grasses and ragweeds.

Scout weed foliage just before planting or check emerging corn for damage or larvae on leaves. Weeds can be treated (preplant) if borers are present.

Apply a rescue type insecticide if 25 percent of emerging corn plants show leaf feeding.

• Stink bugs-These critters primarily are a problem in southern counties. They can attain high levels of infestation in fallow areas and should be managed before crop emergence and when present in cover before planting.

• Slugs-They can become very numerous in undisturbed areas with thick residue levels. Increased tillage before planting may be the best control if slugs are found in large numbers.

• Corn root aphids-They seem to benefit by undisturbed soil. The aphids are blue-green and feed on corn roots growing within ant colonies. Large, irregularly shaped areas of young corn will appear wilted and stunted when attacked.

A broadcast spray of products labeled for corn will reduce ant and aphid activity.

Billburg-This pest, normally, is of little consequence in Indiana, but corn can be treated if damage becomes unacceptable.

Soybeans

Planting corn in the first year after CRP may be a better option than soybeans because of some of the insects beans will face. They include:

White grubs and wireworms- There are no control options for these pests in fields to be planted to beans. If an average of one wireworm per trap or one grub per square foot are found before planting, then planting corn instead of beans may be the best option.

Japanese beetles are highly mobile and can infest fields regardless of field-use history. Treatment thresholds are based on defoliation levels, plant growth stage, cost of control, and commodity price. Generally, treat adults with foliar- applied insecticide when defoliation level reaches about 40 percent at prebloom and 25 percent after bloom.

Slugs-They can become numerous in undisturbed areas with high residue levels. Increased tillage is about the only control option if slugs are found in large numbers prior to planting.

Fruits, Vegetables, and Trees

Insect problems in arbor culture usually require several years to develop. vegetables face many of the same problems as field crops. They also may face increased problems with cabbage maggots and seed corn maggots in soil with a high organic content and possibly increased stalk borer activity. No problems are anticipated for fruit crops with the exception of strawberries, which might see cutworms.

Suggested Reading

E-208 Insect Outlook for Corn and Soybean Fields Previously in Setaside (PDF)

E-209 Relationship Between Tillage Systems and Invertebrate and Vertebrate Pests (PDF)

Sources: Larry Bledsoe 494-8324, Rick Foster 494-9572

Rev 1/96

Cooperative Extension work in Agriculture and Home Economics, state of Indiana, Purdue University, and U.S. Department of Agriculture cooperating; H. A. Wadsworth, Director, West Lafayette, IN. Issued in Furtherance of the acts of May 8 and June 30,1914. Purdue University Cooperative Extension Service is an equal opportunity/equal access institution.