By Brian Hefty

Since the advent of no-till and strip-till, answering burndown questions has occupied a lot of my time each spring for the last 25+ years. Here are some of the top questions and answers to an effective burndown.

Can I Use 2,4-D as a Burndown Herbicide?

Nope. It’s too risky for corn, and it’s definitely too risky for soybeans. I have seen far too many farmers hurt their yields when using 2,4-D, so I have not recommended it as a spring burndown option, nor will I – unless, of course, you are planting Enlist crops. Then, it’s a great option.

How Does the Weather Affect My Burndown?

I’ve seen 1 pint of Clarity sprayed in the spring in front of corn when the temperature was 55 degrees. You would have thought the product never got sprayed. Two weeks later, when the temp was in the 70s, it worked perfectly. Ideally, I would like your daytime temp to be at least 70, your nighttime temp to be at least 50, and the sun shining brightly. I realize this won’t happen for you every day, but what I always tell people is to take your weediest fields and spray those on the best weather days. If you have 100 weeds in the field, who cares if your control is 90% or 99.9%? If you have 1 million weeds, 90% control is an utter failure.

Do You Like Sharpen Instead of Valor or Authority?

Sharpen is a better burndown product than Valor or Authority, but Sharpen is NOT a better choice in front of soybeans. In front of corn and wheat, I absolutely love Sharpen (or Sharpen premixes) and recommend it all the time. Going into soybeans, since our post-emerge options are limited, we need maximum soil residual. The highest rate of Sharpen you can use pre-emerge is 1 ounce before soybeans. That’s not nearly enough to give you a decent residual. Go Valor or Authority in advance of soybeans, and add something else for burndown improvement.

Will Metribuzin Plus Valor or Authority Be Enough for a Good Soybean Burndown?

Probably not. It’s good, not great. Here are 4 options to add to the 3 pre soybean program to improve burndown:

  • Gramoxone plus crop oil. This option is fairly spendy, and it needs great spray coverage, heat, and sunlight to work best. When done right, this choice is fantastic at killing everything, and it’s super-quick.
  • Xtend crops – Xtendimax, Engenia, or Fexapan. These are the only labeled dicamba options, as of right now.
  • Enlist crops – Enlist One. Straight 2,4-D choline works just like normal 2,4-D, only with less drift and volatility.
  • Liberty plus AMS. This is the most expensive option, and just like Gramoxone, spray coverage is a big key.

Do I Really Need a Burndown in Front of Corn?

That all depends on when you plant your corn. This spring has featured record-cold temperatures, so weeds won’t get started as early as normal in many areas. If there are no weeds up a few days before corn emergence, a burndown does you no good. However, just because you don’t burndown, that doesn’t mean you shouldn’t use a residual herbicide. Early season weeds devastate crop yields, so make sure your fields stay weed-free for the first 45 to 60 days after emergence.

What Do I Do if I Don’t Get My Burndown On?

You spend more money, have more weed problems, and most likely, lower yields. If you are in no-till or strip-till, I strongly encourage you to make burndown a priority. In some cases, you may have to stop the planter to spray on a couple afternoons, but it will be well worth it later on.