This edition of Managing Insect and Mite Pests of Texas Corn is a departure from all past versions; it assumes that transgenic technology is now the most common form of insect control for major pests, and that most other pest control decisions will be made for fields of transgenic corn. However, this edition does not deemphasize non-transgenic corn; it includes as much information on managing pests of non-transgenic corn as in the past.
Insect-protected transgenic corn and its associated seed treatments have fundamentally changed the way we practice insect pest management for many key pests. These technologies are deployed before the insects arrive rather than after they begin threatening economic loss.
As with traditional insecticides, we must not use these new technologies carelessly. The pest numbers may not justify the cost of control, and it would pro- mote insect resistance through widespread and continuous selection.
However, these technologies do allow greater flexibility in designing pest management plans. They usu- ally enable growers to avoid using insecticides for key pests, such as caterpillars, which in turn will reduce the threat of the secondary pest outbreaks that often result from pesticide use.
Corn is subject to insect attack throughout the growing season. Some insects may reach damag- ing levels in spite of natural predators and parasites, and the pests may require chemical control. However, insect numbers do not always relate directly to plant damage. Equally important are other factors such as crop rotation, growth stage, moisture conditions, plant vigor, time of year, and parasite and predator abun- dance. Therefore, apply chemicals only after careful evaluation of economic and natural control factors.
To use insecticides wisely, producers must inspect their crops often to determine whether insect or mite pests have risen to damaging numbers. See the indi- vidual insect sections in this publication for methods of determining insect numbers and guides for deter- mining the need for pesticides.
Seed-corn production fields and sweet corn are more susceptible to insect damage than is field corn. Certain pests must be controlled at lower levels for seed corn and sweet corn because they are more sus- ceptible to insect attack and the kernels have higher value. Insect control recommendations in this pub- lication refer primarily to insect and mite control on field corn.
A few insect and mite pests attacking corn in Texas show some resistance to once-effective pesti- cides. Generally, the more extensively a pesticide is used, the more rapidly that resistance develops. Even insecticides with different trade names may have the same active ingredient(s), and alternating between insecticides with the same active ingredients does no good in delaying resistance.
The suggested insecticides tables contain a col- umn titled IRAC group. This is the formal mode of action group recognized by the International Resis- tance Action Committee. To delay the development of resistance, rotate insecticides from different IRAC groups; never apply insecticides from the same IRAC group sequentially.
This publication complements Texas Corn Pro- duction Emphasizing Pest Management and Irrigation (B-6177, 2005), which is available from the Texas A&M AgriLife Extension Bookstore (http://www.agrilife bookstore.org) for $5 per copy. Texas Corn Produc- tion provides details on each corn pest and discusses scouting and economic thresholds.
Policy statement for making pest management suggestions
This publication does not list all of the products registered for corn or all uses for the products men- tioned. The insecticides and suggested use patterns were determined by a consensus of Extension and research entomologists based on field tests. Products listed must meet specific performance standards and avoid undue environmental harm.
The suggested insecticides have been tested to make sure that they provide adequate control in field situations. However, it is impossible to eliminate all risks. Unforeseen or unexpected conditions or cir- cumstances may lead to less-than-satisfactory results. The Texas A&M AgriLife Extension Service assumes no responsibility for such risks; the user of this publi- cation shall assume that responsibility.
Suggested pesticides must be registered and labeled by the U.S. Environmental Protection Agency (EPA) and the Texas Department of Agriculture. The status of pesticide label clearances is subject to change and may have changed since this publication was printed. The user is always responsible for the effects of pesticide resi- dues on livestock and crops, as well as for problems that arise from drift or movement of the pesticide.
Always carefully follow the instructions on the product label. Pay particular attention to the practices that ensure worker safety.
For more information, contact your county Exten- sion staff or contact the Extension Entomologist at the Department of Entomology, Texas A&M University, College Station, TX 77843-2475, or call (979) 845-7026.
The information given herein is for educational purposes only. Reference to commercial products or trade names is made with the understanding that no discrimination is intended and no endorsement by Texas A&M AgriLife Extension is implied.