Posts tagged ‘burndown’

Soybean Burndown Options When 2,4-D Cannot Be Used

Unfortunately, the weather has not been the most cooperative this spring for fieldwork.  Cool, wet conditions are delaying field work and as we get closer to May many growers may drop 2,4-D from their soybean burndown.  Dr. Mark Loux, OSU Weed Specialist, suggests that where it’s not possible to use 2,4-D in a soybean burndown consider applying a combination of glyphosate plus products such as Canopy EX or DF, Valor XLT, or Envive. The addition of one of those products to glyphosate in a soybean burndown will provide generally broad-spectrum control of no-till weeds in the absence of 2,4-D. In addition, adding one of those products to glyphosate will help on the tough to control dandelion. But there are other products that will work well too. Mixtures of glyphosate with Gangster or Sonic/Authority First, are also more broad-spectrum than glyphosate alone. Actually, these products can be more effective for control of emerged ragweeds and marestail (as long as they are not ALS-resistant), but overall Gangster or Sonic/Authority First are less effective on a number of winter annual weeds including dandelion.

In addition to adding one of those soybean residual herbicides mentioned above to glyphosate, Dr. Loux recommends increasing the glyphosate rate from 0.75 lbs ae/A (22 – 24 oz of newer glyphosate formulations and 32 oz of generic glyphosate formulations) to 1.1 or 1.5 lbs acid equivalent per acre.  This increased glyphosate rate will help improve control in mixtures with soybean residual herbicides. But keep in mind that even mixtures of high rates of glyphosate and ALS-based soybean residual herbicides will not control populations of marestail or ragweeds that have developed resistance to both glyphosate and ALS inhibitors. In summary, for growers that cannot use 2,4-D in a soybean burndown OSU strongly recommends using one of the residual soybean herbicides mentioned here plus glyphosate at a rate of at least 1.5 lb acid equivalent per acre.

Full podcast available here:

April 23, 2009 at 7:30 am

Don’t Forget To Include 2,4-D in Burndown Applications

A little over a week ago about the only weed I noted in corn stalks was dandelion.  Now, I see that summer annual weeds such as giant ragweed, lambsquarters, and a few others have started to emerge in central  and north-central Ohio. The emergence of these weeds increases the need for appropriate preplant (burndown) herbicide mixtures in no-till crops.

This past winter you may have been considering whether or not you need to add 2,4-D with your burndown applications.  Because of the prevalence of dandelion and glyphosate-resistant weeds the addition of 2,4-D in preplant herbicide burndown applications is very important in achieving effective weed control prior to planting.  Unfortunately, there are several weeds that have expressed glyphosate resistance (or tolerance, whatever you want to call it).  Just a few examples of glyphosate tolerant weeds in our area include marestail, common/ giant ragweed, and lambsquarters.  Of these, I am most concerned with marestail (Conyza canadensis).  This weed is difficult to control in the best of situations, let alone when it gets > 8″.  OSU Weed Scientist Mark Loux recommends controlling this weed when it is 4″-6″ or smaller.  I completely agree, as I have observed the difficulting in controlling this weed once it bolts. And, unfortunately, postemergence control options with this weed are usually not overly successful.

We are still early enough in the season that it is more important to include 2,4-D in preplant herbicide applications rather than planting the crops and controlling weeds long after planting. For the latest updates on weed control strategies, visit the OSU C.O.R.N. newsletter at

Full podcast available here:

Edit (04/08/09): I was asked ‘What is a burndown?’  Good question, and I apologize for using the ag jargon.  A burndown is a herbicide application made to an ag field several days (or even a couple of weeks) prior to planting.  Burndown applications are made in no till fields.

April 8, 2009 at 7:30 am

Delayed Planting Means a Change in Burndown Strategy

Wet weather has caused some fields to miss an early burndown.  I recommend increasing your glyphosate rate to attack large weeds.  There is one silver lining to the delay in planting with regards to weed control — find out about it by listening to my podcast here:

May 12, 2008 at 9:35 pm


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