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A weed control primer
Dr. Victor Martin

The drought monitor report as of Tuesday, March 21 indicates exceptional drought continuing to envelope almost all of Barton, Pawnee, and now into Stafford Counties. The six to ten-day outlook (to March 28 to April 1) indicates near normal temperatures and precipitation. The eight to 14-day outlook (March 30 to April 5) indicates a 33 to 40% chance of leaning to below normal temperatures and near normal precipitation. As a point of reference, April is when our average annual monthly precipitation ticks upward to around three inches. However, while that will keep wheat hanging on and allow some moisture for corn planting, normal will do little to recharge the soil moisture profile.

Last week, we discussed why weeds are so good at what they do. This week, let’s briefly discuss Weed Control 101 for crop production. This will just brush the surface of what goes into a successful weed control program.

• The first step is to know what weed problems exist. What grasses and broadleaves are present? Are they annual, biennial, and/or perennials? Does the field have herbicide resistant? What is the cropping history of the field?

• Assuming you have an idea of what weed problems are present, the next step is to develop an (IPM) Integrated Pest Management Program. People think conventional agriculture simply controls pests chemically but the reality is different. IPM involves a variety of methods, including herbicides. IPM plans should be cost effective, suppress weed pressure to an acceptable level, and protect the environment.

• Depending on the climate, soil type, and other factors, develop as diverse a crop rotation as possible involving both grass and broadleaf crops. The better the precipitation and/or irrigation, the more diverse the crop rotation possible. The concept here is that it’s easier to control broadleaf weeds in grass crops and vice-versa. Part of the rotation may have to include an extended period of fallow, if practical, when problem weeds are present for aggressive cultural and chemical control.

• At planting, start with weed free field. This may be achieved chemically, with tillage, or a combination of both. Some producers achieve this with a cover crop prior to planting that is allowed to grow, cover the soil, killed, and left in place.

• The best weed control is an actively growing crop that covers the soil rapidly. So deciding on the proper row spacing and plant population while providing the best physical and chemical environment for the crop is key.

• While not inexpensive, a preemergence weed control program that allows the crop to get ahead of weeds, one that controls grasses and small seeded broadleaves will allow the crop six weeks or so to become established.

• Finally control weeds when they are small and in the seedling stage. For row crops and when part of the program, cultivate. Often, herbicides are involved. The key for herbicides is to not use the same mode of action but vary them to prevent herbicide resistance from becoming a problem. Often use several modes of action at one time.

• There is much, much more but hopefully this gives everyone an idea of what is involved.


Dr. Victor L. Martin is the agriculture instructor/coordinator for Barton Community College. He can be reached at 620-792-9207, ext. 207, or martinv@bartonccc.edu.