One of the most important steps in no-till weed control is to start with a clean field. This means you should use a burndown treatment to make sure the field is clean at or shortly after planting.

Small weeds draw a lot of moisture away from the crop and can reduce yields. Research at Midwestern universities show significant yield losses can occur due to small weeds.

These small weeds are harvesting too much soil nitrogen and other nutrients. This drop in available early season nitrogen can cause the crop to produce well short of its yield potential.

The bottom line is we need clean fields to maximize yields. Usually, a two-pass herbicide system is the best because it gives us two opportunities to apply herbicide mixtures that can provide full-season weed control.

With a two-pass system, lower rates usually can be used and weeds will be controlled much more effectively than using high rates with one pass. Consider saving some dollars on the herbicide products and putting those dollars toward application to help offset the cost of a second pass.

I’ve often seen producers not use a burndown treatment on soybeans. In these cases, the weeds begin to outgrow the small bean plants. These weeds take valuable sunlight and nutrients away from the beans and reduce yields by 10% to 20%.

When we first started no-tilling in the early ‘80s, weed control was really a challenge because we didn’t have the burndown herbicide options we have today. Glyphosate helped to revolutionize our ability to burn down weeds and improve weed control in no-till.

Avoid Resistance

However, because of widespread use of glyphosate, more weeds are becoming resistant to this key chemistry. If we aren’t careful, this resistance could really reduce the effectiveness of glyphosate as a burndown.

Luckily, there are good options on the market that through their use help lower the possibility for resistance.

As with many agricultural practices, rotation of products and weed-control systems is essential to reduce resistance and improve the chances of success with our weed-control programs.

Follow these simple guidelines to avoid herbicide resistance in weeds:

Tankmix and/or rotate herbicides. Rotate herbicides among different modes of action and use tankmixes of different modes of action.

Rotate crops. This will also allow you to use several different chemical families and modes of action.

Scout fields regularly for weeds. This will allow you to select the best herbicide for the job.

Manage your rates. Use rates that effectively control the weeds, but don’t overapply.

Rotate hybrids or varieties. If you raise consecutive corn crops, you might want to rotate between Roundup Ready, LibertyLink or conventional corn. Make sure you keep good records so you spray the right herbicides.

Changing Weed Pressure

Consider rotating the time of application of various herbicide programs.

Every year we have different weather conditions in the spring, which bring on different weed flushes.

Just because you do an early post application one year does not mean an early post spray each year will perform the same. You may need to switch herbicides based on the weeds that actually grow that year.

Why do these weeds change? A particular herbicide may control some types of weeds better than other weeds. As these weeds are controlled, they then become less competition for weeds that weren’t controlled as well, which now begin to flourish.

Thus, you need to change the herbicide to beat new troublesome weeds.

Something else that is neat about no-till is that your weed pressure can be reduced over time. Several years ago, I visited one of our research station’s herbicide demonstration plots. At that time, they had a minimum-tilled plot and a 100% no-tilled plot.

A couple years later, I learned they had removed the no-till plot. The scientists said the continuous no-till plot no longer had enough weed pressure to evaluate herbicides. Most of the weed seeds had germinated in the top few inches of the soil and the plot no longer was getting enough weed pressure to evaluate new herbicides.

I thought this was an excellent showcase for no-till and hoped they would leave the plot just to show another benefit of no-till.

Really, weed control on our farm has become easier with all the new technologies. We just have to be careful not to get lazy and stick with one technology, but instead rotate them to improve weed and pest management.