Production Practices

Corn is grown in nearly every area of the state with the highest density of corn acreage in the
central section. Planting may begin as early as the 15th of April in Southern Illinois and the 1st
of May in Northern Illinois.

In areas of dairy production, such as around St. Louis and in the Northern tier of counties, corn is
primarily used for feed grain. In the central part of the state corn may be processed for oil,
sweeteners, and corn meal or shipped to feed grain or export markets. Only about 120,000 acres of
corn is ensiled, and most of that is in the dairy region of the state. Much of the state also has
extensive seed corn production fields, which is affected by pests with the same frequency as grain
corn. However, commercial seed corn production fields are more intensely scouted and a higher level
of management is used to control pests.

Because most farmland is in the state is owned by landlords, there is little tolerance for poorly
managed fields. This is further exacerbated by the level terrain of much of the state and the ease
with which uneven stands or weeds can be seen. This low tolerance often drives farmers to maintain
exceptionally clean and aesthetic fields.

There is currently a great deal of controversy over the marketability of grain with GMO traits. In
1999, with over 30 percent of all corn bearing at least one GMO trait, this has come to be a
significant concern.

Cultural Practices

Corn is typically grown in a rotation with soybeans and less often with wheat, sorghum, or alfalfa.
About 30 percent of the corn in the state is grown as continuous corn. Conservation tillage
practices are regularly used for field corn with no-till practiced on about 20 percent of the corn
acreage annually. About 50 percent of the acreage is cultivated with a row cultivator and an
estimated 40 percent is rotary hoed annually. Approximately half of all pesticide applications are
applied by the farmer and the other half are applied by licensed dealers and applicators. However, a
greater proportion of reemergence herbicides are applied by the farmer than is applied by contract
applicators. This situation is reversed for post emergence herbicide applications. Approximately 90%
of insecticides are for soil insects and are applied by the farmer at planting with planter boxes.
Fungicide use is generally limited to the seed treatments that have been applied to the seed prior
to purchase.

Insect Pests

In a typical year, the major insect pests can cause severe economic damage in 15% or more of the
total acreage. The four major soil insect pests of corn (corn rootworms, cutworms, white grubs, and
wireworms) all feed on some subterranean part of the corn plant during their life cycle. The type of
injury that each pest inflicts is different, and the occurrence of the insect and damage caused by
each insect vary significantly from year to year and region to region.

Insects

Black Cutworm (Agrotis ipsilon)
Black cutworm adult moths migrate to southern Illinois from March-May and lay eggs in vegetation in
or around cornfields. The eggs hatch and larvae feed on available vegetation, Earlier instars feed
on corn leaves; later instars cut the plants off near the ground. Fields subject to cutworm
infestation often have preplant infestations of weeds, heavy surface debris, poor drainage, or a
history of cutworm damage. An annual average of 3% of all fields are treated with post harvest
insecticides, and up to 7% of acreage is treated with preplan or preplan-incorporated insecticide
applications. Postemergence rescue treatments are justified when 3% or more of plants are cut and
larvae are still present; preventative treatments are best utilized in no-till systems or where
cutworm damage forces replanting of field.


Grasshoppers (Malanoplus spp.)
Grasshopppers populations usually thrive during hot, dry summers when their naturally-occurring
pathogens are suppressed; populations also tend to increase the year after a drought. Grasshoppers
occur throughout Illinois and are usually most damaging in the southern half of the state.
Grasshoppers are of minor to moderate importance in Illinois, as they usually prefer to feed on
weeds but will readily move into crops if weeds are not available. Up to 11% of field margins may be
treated during outbreak years.

Stalk borer (Papaipema nebris)
Stalk borer moths lay their eggs on field edges from late August to frost. Fields with poor weed
control are most likely to suffer damage from stalk borers. While relatively few acres of corn
fields are treated annually for stalk borers, the distribution of borers corresponds with the
distribution of weed hosts. The larvae borer into the stalks of plants, causing, death, twisting,
bending, tillering, and many infested plants will not produce an ear.

Twospotted Spider mites (Tetranychus urticae)
These mites suck fluids from corn plants; heavy infestations of twospotted spider mites cause leaves
to wilt, turn yellow, and die. In drought conditions, spider mites can cause devastating losses.
Twospotted spider mites are generally a minor pest and on the average, 1 percent of corn acres are
treated annually.

White Grubs (Phyllophaga spp.)
White grubs are relatively minor pests in Illinois, and damage is usually minimal, with less than 1%
of acres treated for grubs annually. White grubs are larvae of several species of scarab beetles,
often called May or June beetles. The species most damaging to corn are in the genus Phyllophaga and
have three-year life cycles. Peak levels of injury usually occur during the year following large
flights of the adults. The beetles prefer to lay eggs in ground covered with vegetation, for
example, weedy soybean fields and sod. White grubs chew off roots hairs, reducing water and nutrient
uptake, and severely damaged plants will wilt and die, causing severe stand reductions. Symptoms of
white grub injury visible above ground are irregular emergence, reduced stands, and stunted or
wilted plants. Injured plants often cannot take up phosphorous efficiently, so the plants may turn
purple. Injury is generally spotty throughout the field.

Diseases

For corn, the most frequently cited diseases and pathogens are:

* stalk rots, primarily anthracnose (Colletotrichum graminicola, and Fusarium spp. and Diplodia spp)
* ear rots (Fusarium spp., et al.)
* leaf blights (Helminthosporium maydis, Exerohilum turcicum)
* viruses (Maize dwarf mosaic, maize chlorotic mottle, corn lethal necrosis).

Common soil borne fungal infections produce early season stand losses that can adversely affect crop
yields.

In Illinois, farmers are utilizing conservation tillage systems that assist in soil and water
retention. However, the presence of a mulch layer from previous crops also modifies many of the
physical, chemical, and biological components of the soil and its ecosystem. Numerous studies have
documented changes in temperature, water retention capacity, soil microbiology, soil tilth and
structure, and chemical composition when farmers have modified their tillage from conventional
tillage to either reduced or no-tillage systems.