10 Tips for Effective Corn Weed Control

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Corn rows at ground view

Every season, you work with customers to find the right herbicides to keep their cornfields clean, but you know there’s more to effective weed control than just powerful products. The steps they (and you) take throughout the year can have a huge impact on how well those products perform. 

Here are 10 tips you and your customers can take to get the most out of their corn weed control programs: 

1.       Figure Out the Weed Spectrum — The first tip is also one of the most important: Know thy enemy. Obviously, you and your customers need to know which weeds they need to control to create the right program. However, it’s important to not only know which weeds are a problem now but also keep track of how the spectrum may be changing and which problem species may be moving into your area. 

2.       Know the Numbers — A good corn weed control program should contain multiple modes and sites of action. As a reminder, the mode of action is how the herbicide works and the site of action is where the herbicide works within the weed to kill it. Knowing corn herbicide numbers can help your customers ensure they’re switching up modes and sites of action to help prevent resistance. In addition to multiple modes and sites of action, using products that provide residual activity in both preemergence and postemergence applications can help keep fields clean long into the growing season. 

3.       Understand the Soil — Your customers’ soil can have a major impact on herbicide efficacy. Soil texture, organic matter (OM) content, pH, moisture and tillage can all affect soil-applied herbicide activity. Having a good understanding of their soil attributes can help farmers dial in the right products and practices to use. 

4.       Test the Water — Just like soil, the type of water your customers use in the spray tank can have an effect on chemistry efficacy. Testing the water for both pH and hardness is very important. If the water is hard or it isn’t acidic enough, the herbicides may not work as well. Luckily, farmers can use adjuvants to fix water issues they might find. This leads us right into Tip 5: 

5.       Use Adjuvants — Adjuvants can be enormously helpful for getting the best out of herbicides. Farmers just need to remember: Not all adjuvants are the same and using the wrong ones can result in crop damage, doing more harm than good. 

6.       Time It Right — As with many things in life, the right timing is paramount. Your customers need to take a number of conditions into account for correctly timing their herbicide applications. Those include the products they’re using, corn growth stage and weather. Don’t forget to watch for and avoid temperature inversions when making applications. 

7.       Tank-mix in Order — Once it’s time to start adding chemistries to the tank, getting the order right can mean the difference between an effective mix and a big, old mess.  

8.       Scout Regularly — Regular corn scouting is important for good weed control. Encourage your customers to get into their fields every couple of weeks to look for escapes. This can help farmers decide whether another application is necessary. In the long term, this can also help farmers better understand the weed spectrum in their fields and plan more effective weed control programs. 

9.       Apply in Fall — Although spring gets the most attention when it comes to weed control applications, fall deserves some consideration. If possible, applying a fall burndown can set farmers up for an easier spring. Not only can a fall burndown stop certain problem weeds like marestail from overwintering but also it can free up some time for other spring fieldwork.  

10.   Store Products ProperlyStoring herbicide products in the right containers and the right temperatures will help ensure they’re still effective when it’s time to use them. 

This is, of course, a high-level look at each of these tips. As you know, it’s very important to read individual product labels to find the right way to take these steps. Your Corteva Agriscience territory manager is also a great resource if you have questions about specific products.