I sprayed some of my beans Saturday and then finished Monday afternoon. It would have been nice to get them all done Saturday so I did not have to go back Monday and look at them! The herbicides we need to control tough weeds like waterhemp and giant ragweed will turn some of the bean leaves brown. Trade name herbicides like Flexstar, Cobra and Blazer are group 14 herbicides or PPOs. There are fancy chemical names, but farmers call this class of herbicides "the burners."

When the Round-Up Ready technology hit the market in 1996, we did not have to use "the burners" any more. After years of using Round-Up, some of the weeds adapted, some developed resistance and Round-Up did not perform like it used to. Now "the burners" are back in herbicide programs. It is tough when you are spraying a nice looking bean field knowing that the next day many of the bean leaves will be brown.

Agronomists tell farmers to spray their beans and go fishing for a few days! How badly the beans turn brown depends on the humidity, temperature, time of day and other factors that are hard to explain. Sometimes you spray the beans thinking you will really burn them and it turns out it was not too bad. Other days it is the exact opposite.

It is hard to believe but at labeled rates these "burner" herbicides have no impact on soybean yields! Tom Hoverstad, a scientist at the Southern Research and Outreach Center-Waseca, told me they did a lot of research on "the burners" back in the 1980s. They tried to burn the beans. He said they made the beans look really sick. The biggest yield impact was 2-3 bushels an acre. However, you have to pay attention to the label. If you apply "the burners" in July when the beans are flowering, you will affect the yield in a big way.

Even though you do not want to burn your beans, you have to control the weeds. The picture at top shows my beans Monday afternoon before I sprayed them. The photo below is my burned beans after I sprayed them Saturday. On the right is the headlands that were sprayed Saturday. On the left is the unsprayed beans. See how green they are? We do not like to burn our beans, but it is much easier than pulling the weeds one by one!


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