By: Harold Watters, OSU Extension Ag Crops Field Specialist

Our OSU Extension AgNR educators observed soybean fields across the state again this fall to see what was out there for our annual fall soybean weed survey. I was supposed to share this early enough so you could at least get a fall application on to get a head start on controlling marestail, but it seems we have more problems than that to deal with.

Statewide our most frequently observed weed problem was again marestail. It was present in 36% of the fields. The second most likely observation was weed free — at 29% of the fields. That’s a big jump over several years ago, and likely due to LibertyLink, Enlist, and Extend soybeans. Third, fourth and fifth places in a three-way tie were giant ragweed, volunteer corn and then giant foxtail (or just generic grass) — all in about 19% of the fields. Next, and getting ever more widespread, is waterhemp at 15% of the fields across the state. Continue reading Weed Management in Ohio, Update 2019 →

By: Harold Watters, CCA, Ohio State University Extension

So this year I am getting even more calls and comments on run away marestail.

“Last year I killed it, this year not so much” is often the remark I hear. And following is my response regarding Horseweed (Conyza canadensis), or Marestail as it is known in Ohio. This may be a new weed to you but the western side of the Ohio and particularly the southwest corner have been fighting it since about 2002. It takes a comprehensive effort, but it can be well managed. Continue reading Weed Answers for 2020 Start this Fall →

By: Mark Loux, OSU Extension

If you have never applied herbicide in fall to burn down winter annuals, or done it only infrequently, this might be the year to make an investment in fall herbicides.  Fall treatments are an integral component of marestail management programs.  They also prevent problems with dense mats of winter annuals in the spring, which can prevent soil from drying out and warming up, interfere with tillage and planting, and harbor insects and soybean cyst nematode. Continue reading Fall Herbicide Treatments – Even More Important This Year? →

By: Mark Loux, OSU Extension

If you don’t already have to deal with waterhemp or Palmer amaranth, you don’t want it.  Ask anyone who does.  Neither one of these weeds is easy to manage, and both can cause substantial increases in the cost of herbicide programs, which have to be constantly changed to account for the multiple resistance that will develop over time (not “can”, “will”).  The trend across the country is for Palmer and waterhemp to develop resistance to any new herbicide sites of action that are used in POST treatments within about three cycles of use.  Preventing new infestations of these weeds should be of high priority for Ohio growers. Continue reading No Pigweed Left Behind – Late-Season Scouting for Palmer Amaranth and Waterhemp →

By: Mark Loux, OSU Extension Weeds Specialist

Managing cover crops in a year like this can challenge even those with the most experience. A few suggestions regarding termination of covers:

• Increase glyphosate rates to compensate for larger size, and consider applying alone or just with Sharpen. Mixing glyphosate with other herbicides or ATS can reduce its activity on grass covers, especially when large. Herbicides that can antagonize glyphosate include 2,4-D, metribuzin, atrazine, and flumioxazin and sulfentrazone products. Sharpen has not caused a reduction in glyphosate activity on grass covers in university research. One approach would be to apply the glyphosate or glyphosate/Sharpen first, wait a few days, and then apply residual herbicides. Continue reading Managing Big, Wet Cover Crops →

By: Harold Watters, Ohio State University Extension Agronomic Systems Field Specialist

So I got some calls after our Extension Fall Weed Survey — if these are the problem weeds, then how do you deal with them?

It is becoming apparent that with the move to herbicide tolerant crops, we aren’t necessarily getting rid of all of our weeds — only 30% of our fields are weed free. Giant ragweed moved back into first place for worst weed, seen in 34% of fields overtaking marestail seen in 30% of fields. And then there is the pigweed problem — waterhemp appeared frequently, so did redroot pigweed and then there are the concerns about Palmer amaranth and its escape across Ohio.

Continue reading Ohio Fall Weed Survey Follow-Up →