AgDM newsletter article, February 1999

Controlling weed management costs

By Bob Hartzler, Extension Weed Management Specialist, 515.294.1923,

Herbicides are the main component of most weed management programs in corn and soybeans.  To reduce weed control costs, the herbicide program must be changed. Keep in mind that the cost of herbicides usually is relatively small compared to the economic loss that can be caused by uncontrolled weeds. Any major changes should be carefully thought out to consider the risks and benefits associated with those changes.

Before making changes in your weed management program, consider the following questions:

Reducing weed management costs will require a higher level of management to maintain consistent weed control. The following strategies may provide opportunities to improve the efficiency of your weed control program. More specific information on these strategies is provided in ISU Extension publication IPM-36: Reducing Herbicide Use in Field Crops.

Herbicide selection

Comparing costs of herbicides is difficult because prices vary depending on company programs, quantities purchased, and other factors. The first factor to consider in selecting a herbicide is whether it will control the weed species found in the field where it will be used.

However, several other factors should be considered, including:

Many herbicide manufacturers recommend a specific program with their chemicals. A farmer may get rebates or other incentives if they buy into the entire program. These programs are designed to provide consistent weed control over the entire range of conditions encountered in the region.  While these programs may provide low-risk weed control, they essentially remove the farmer's skill and knowledge from the decision-making process. Growers willing to customize a program to their specific skills and weed problems may be able to develop a more efficient program than those offered by companies.

Reduce herbicide use with increased management

Most growers are not in a position to eliminate herbicides from their weed management program.  However, many may be able to significantly reduce the amount of product used. Maintaining consistent weed control while reducing herbicide use requires a higher level of management, and may involve strategies such as increased timeliness of application or supplementing herbicides with mechanical strategies.

Specific tactics that may allow reductions include:

All of these strategies require increased management, but they are proven options for those growers willing to invest the time and effort. Field scouting is an essential component of all of these strategies in order to stay ahead of any potential weed problems. Many of the options will require that the farmer have a sprayer to allow banding or timely applications.

Adjust management program according to weed population

Weed infestations are rarely uniform across a field, yet most farmers use the same program across the entire field. In addition, many growers use the same program for all fields, even though different fields have widely varying weed populations. Adjusting programs to match weed infestations is a relatively simple means of increasing efficiency. One method of accomplishing this is to make a separate herbicide application to spot-treat problem areas in a field. This will allow a less intensive treatment to be placed over the entire field. The reduction in herbicide use over the entire field can more than cover the cost of the second trip needed for the spot treatment of problem areas.

Successful weed management is a critical component of profitable crop production. Efficient weed management programs are based on economic returns rather than the ability to maintain weed-free fields. It is recommended that farmers start slowly when changing weed management programs.  Growers should select fields where weeds have been controlled successfully in the past in order to avoid heavy weed pressures. An effective scouting program is essential to monitor weed populations throughout the growing season.


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