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General Production Information
Grain sorghum is typically grown in the southern part of Illinois. The number of acres planted to sorghum has been decreasing for about 15 years. Because of its tolerance for drought, grain sorghumis often grown the year after a dry spell, as farmers seek to assure that they do not experience two successive years of crop failure. The use of grain sorghum in Illinois is principally as feed for cattle. A low market value, yields lower than corn, and difficulty in controlling weeds in the crop,
generally restrict the amount of acres planted to sorghum in any year. Sorghum is often planted (double cropped) after winter wheat is harvested. If the grain does not mature before frost the cropis harvested for ensilage. Insect Pests
Black Cutworm (Agrotis ipsilon) Black cutworm adult moths migrate to southern Illinois from March-May and lay eggs in vegetation in or around sorghum fields. The eggs hatch and larvae feed on available vegetation, Earlier instars feed on 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 preplant or preplant-incorporated insecticide applications.
Corn Leaf Aphids (Rhopalosiphum maidis)
Winged corn leaf aphids are blown into Illinois by the prevailing winds. Hot, dry weather is unfavorable for natural enemies and can lead to severe infestations of aphids, Heavy infestations will wilt, curl, and cause necrosis of the upper leaves. Aphids excrete honeydew, which coats leaves and reproductive structures and may interfere with pollination.
Corn Rootworm, Western (Diabrotica virgifera ), Corn Rootworm,Northern(Diabrotica barberi) The larvae of corn rootworm beetles cause the most economic damage every year in Illinois. The larvae overwinter in the soil and undergo three instars while feeding on roots, causing lodging and reducing nutrient and water uptake. Northern corn rootworm beetles can be controlled by rotating soybeans with first-year corn. The larvae cannot survive in the soybean roots and starve to death. Northern corn rootworm beetle is most damaging in corn and sorghum planted after corn. In the past few years, western corn rootworm beetles have apparently changed their behavior by laying their eggs in soybean fields. The conclusion is that crop rotation itself has selected for a rootworm strain that circumvents sorghum-soybean crop rotation. By laying their eggs in soybean fields the female beetles insure the survival of their larvae in the subsequent year because the field will be planted to corn or sorghum. These larvae have had a very damaging effect in first year sorghum planted after soybean in east-central Illinois, and the problem is spreading slowly to the west and more rapidly
to the east.
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