As the season progresses, you may see some "goose-necked" corn plants in your fields. The ìgoose-necking" is a result of the corn plant attempting to straighten up again after it has begun to lean or lodge after a rain or windstorm. The leaning or lodging of the corn stalks can be caused by corn rootworm damage and/or high rates of herbicides applied under stressed conditions. To correct this in future crop years, it is important to correctly diagnose the cause of the "goose-necked" plants.

Corn rootworm damage is usually first seen as "goose-necked" corn plants in the field. Looking a little closer at the leaning or lodged corn plants, you will see some feeding on the roots as well as tunneling and gouging of the larger roots. The feeding on the roots and tunneling is caused by the tiny corn rootworm larvae that hatch in mid-June when soil temperatures reach 10 to 11o C. The corn rootworms can destroy both the main and brace roots of the corn plant allowing the plants to be knocked over. Plants with a reduced root system lack vigour due to interference with the uptake of nutrients and moisture. If lodging is bad enough, harvest losses will further reduce yield.

By far, the most effective method of control for corn rootworm is crop rotation; that is, donít grow corn in the same field more than one year in a row. Almost all rootworm eggs are laid in corn fields. The larvae that hatch from those eggs can survive only on corn roots, therefore, rotation with another crop for one year will almost eliminate the risk of rootworm damage.

If crop rotation is not practical and corn rootworms are predominant in your area, it may be necessary to treat 2nd year corn fields, especially if on clay soils. Insecticides on average only reduce the beetle emergence by 25 per cent. In recent years there has been greater variability in the control of corn rootworms with soil insecticides. For these insecticides to be effective, care must be taken to apply the product correctly. For more information on the correct use and the list of chemical insecticides available see the OMAFRA - Field Crop Recommendations Publication 296.

If corn rootworms were a problem in some of your fields in 2000, keep crop rotation in mind when deciding your 2001 cropping plans.