Showing posts with the label resistance

Check Dicamba Soybeans After Spraying

Farmers are turning to an old technology this year to control weeds in their fields. Here’s what they can expect from a new, old-product.

Dicamba has been around for about half-a-century. It is a corn herbicide, but soybeans have been modified to tolerate it. This was done because so many weeds have modified themselves to resist being killed by glyphosate, commonly known as Round-Up. The primary problem, says University of Illinois Extension Weed Scientist Aaron Hager, is waterhemp, “it, has never been excellent on any of the pigweed species. It can be good. It can be very good, but it is not excellent. It is not as consistent.”

This inconsistency makes the timing of dicamba applications extremely important. Without a doubt, says Hager, most post applied herbicides are going to do a better job of controlling a full suite of weeds in a field when the weeds are less than three to four inches in size, “Certainly, with something like dicamba and waterhemp, our recommendation to farmers is to treat very, very small weeds, but to go back in about 10 to 14 days and to scout those treated fields. Look to see what the efficacy has been. Sometimes we can twist up these pigweed plants, but that doesn’t mean they will necessarily be completely controlled.”

Look to see what the efficacy has been. Sometimes we can twist up these pigweed plants, but that doesn’t mean they will necessarily be completely controlled.

It is possible for the weeds to recover, flower, and produce seed. And that, says Aaron Hager, is something to avoid.

Marestail Control Prior to Planting

link to article online

Farmers in Illinois, other states too, are struggling to control glyphosate resistant weeds. Marestail can be one of the most challenging under no-till conditions prior to planting soybeans. More often than not farmers are using a tank mix of glyphosate and 2,4-D (two-four-dee). Sometimes the problem is that the weed is already too big to control, at others says University of Illinois Extension Weed Scientist Aaron Hager is its just that the 2,4-D isn’t doing the job any better than the glyphosate.

Quote Summary - Well, there are some alternatives that can be used for control of mares tail in a burn down scenario. A product called Sharpen could be included with glyphosate/2,4-D to try to increase the efficacy on the marestail and if that is the case be sure to include a methylated seed oil with any application that has Sharpen with it. Or alternatively you could switch completely over to something like a glufosinate product, like a Liberty or Interline containing product or something like Gramoxone. Either of those will typically perform better when used in combination with metribuzin and probably 2,4-D in the tank as well.

Tillage is another option, however, Hager says to delay it until field conditions are suitable and be sure to till deep enough to completely uproot all existing vegetation.

4 Step Weed Control Plan for Corn or Soybeans

Since the 1960’s farmers have been using herbicides to control weeds. Frankly, herbicide formulations haven’t changed that much and the weeds have managed to find ways to adapt. Todd Gleason has this four step plan from the Univesity of Illinois to control them in corn or soybeans.

Some weeds have become resistant to the herbicides farmers use to control them. Others have lengthened their germination period, emerging later in the season, avoiding early spring control methods. University of Illinois Extension Weed Scientist Aaron Hager has a four step plan farmers can use to maintain a competitive edge in corn or soybeans. It starts by planting into a weed free seedbed.

Quote Summary - It is easy to achieve a weed free seedbed by either replant tillage, burndown herbicide or a combination of those two. Given the challenges of weather and of resistant populations it is advisable not to plant into existing weed populations or any green vegetation without adequate control ahead of time.

Step two in the plan is to select an appropriate residual herbicide. Be sure it provides very good control of the most problematic weed species in a given field. Pay attention to the label, says Hager, and always apply the recommended rate for the spectrum of weeds in the field.

> Quote Summary - The third step is to make timely post emergence applications. Base those on just not the number of calendar days after planting, but rather base those post decision on adequate scouting. So, return to the fields about two weeks after crop emergence. Scout the fields and determine the weed size, crop development stage and make the decision on a timely application of a post herbicide.

The final and fourth step is to go back to the field seven to ten days later and evaluate how well the post emergence herbicide application worked. It may be that another germination of a weed species warrants a second application. This won’t be know without a return trip.

If we fail to go back and look at how well the product performed, or the level of crop injury we see soon after that application, we could have some very significant challenges later in the growing season.

The days of set-it-and-forget weed control have ended. Todays farmers must scout fields for competitive weeds before during and after the growing season.

Four Step Weed Control Plan for 2016

Farmers battling herbicide resistant weeds are running out of control options. University of Illinois Extension Weed Scientist Aaron Hager has this four step recommendation. You may read detailed information of his four step weed control plan online.