How to Get Rid of Crabgrass in Corn

Because corn germinates at higher temperatures than most weeds, crabgrass is particularly difficult to control in corn. By the time crabgrass is ready to germinate, the residual effect of other herbicides will have worn off. That problem, coupled with the fact that the corn has not developed to sufficient height to shade and inhibit the growth of crabgrass allows the weed to get a strong foothold. Unfortunately, most common herbicide treatments are ineffective in controlling crabgrass. A few pre-emergent products will work in preventing germination, but once the corn itself has germinated, the methods for eliminating crabgrass are limited to those containing the chemical mesotrione.

Difficulty: Moderately Challenging

Instructions

Things You'll Need:

• Herbicide containing the active ingredient mesotrione
• Tractor mounted agricultural sprayer
• 80-degree flat fan nozzles
• Protective gloves

1. Drain and rinse the sprayer's solution before using to remove any residue from previously used herbicides. Any residual herbicides left in the tank could possibly be harmful to corn.

2. Agitate the mesotrione before mixing it with water. The dilution rate for mesotrione is 1 gallon to 100 gallons of water. (One gallon of Mesotrione treats 40 acres.) It is best to fill the tank with water before adding the herbicide. Check the label for handling precautions, and wear protective gloves when you work with mesotrione.

3. Adjust the spray nozzles so the spray will be uniform and provide a medium-sized droplet with a minimum of drift. Pump pressure should be set at 40 psi with the flat fan nozzles angled at 45 degrees.

4. Agitate the solution in the tank if there has not been any motion for over five minutes to insure that the solution is thoroughly mixed at all times. Failure to keep the product mixed will cause uneven coverage and possibly cause dangerous levels of undiluted mesotrione in some areas.

5. Store any unused product away from seeds or fertilizers. Dispose of empty containers by rinsing them at least three times and then send them to a recycling center or sanitary landfill.

Tips & Warnings

• Mesotrione is effective in controlling crabgrass in plants that are between two and ten inches tall.
• Applicators should wear long-sleeved shirts and long pants, shoes and socks, and Butyl rubber or nitrile gloves.
• Care should be taken to avoid spraying mestrione in standing water.

References

• "Improved Methods of Corn Growing and Intense Cultivation"; Jerome Boneypart Armstrong; 2009

Resources

• USDA Corn Crop Weed Control
• Mesotrione Fact Sheet