Get your Waterhemp Populations Screened for Herbicide Resistance

Jul 27, 2021

By Mark Loux

We have been screening a random sample of waterhemp populations for herbicide resistance over the past two years. Herbicides used in the screen include mesotrione, atrazine, 2,4-D, fomesafen, and metolachlor. Results of our research show that it’s possible for Ohio waterhemp populations to have some level of resistance to one, several, or all of these herbicides. Glyphosate is not included because we assume almost all populations are already resistant to this. We are also part of a regional project that has been screening for dicamba and glufosinate resistance with populations that we supply, although none has been identified to date. Our sample size has been small so far, so at this point we are looking to expand our screening to include waterhemp populations submitted by anyone in Ohio looking for more information about their response to herbicides. It’s preferable to have seed from waterhemp plants that have survived POST herbicide treatments, or where it appears that preemergence herbicides were fairly ineffective, if possible. But we will screen any populations provided within the constraints of time and greenhouse space. For a quick reminder about how to tell when seed from waterhemp is mature, check out this video. When seed is mature, you can cut off seedheads and place in an open paper bag until ready to get them to us. Or just shake heads into some type of container to collect seed. Send us an email and we will figure out the best way to get seed to us, or if you need more information. loux.1@osu.edu

Also – a reminder that while we would like to have seed from surviving waterhemp plants, the most effective method of preventing future problems with this weed is to not let any go to seed. Not only because plants that survive may have resistance, but because they produce gobs of seed that will result in misery the following year. Removal of these plants should have high priority right now. However, where it’s apparent that this is not going to happen for whatever reason, make a note of the infested fields, and check on them starting in a couple weeks for seed. This should help us to get a better handle on how resistance in waterhemp is evolving.

Source : osu.edu

Video: Spring 2026 weather outlook for Wisconsin; What an early-arriving El Niño could mean

Northeast Wisconsin is a small corner of the world, but our weather is still affected by what happens across the globe.

That includes in the equatorial Pacific, where changes between El Niño and La Niña play a role in the weather here -- and boy, have there been some abrupt changes as of late.

El Niño and La Niña are the two phases of what is collectively known as the El Niño Southern Oscillation, or ENSO for short. These are the swings back and forth from unusually warm to unusually cold sea surface temperatures in the Pacific Ocean along the equator.

Since this past September, we have been in a weak La Niña, which means water temperatures near the Eastern Pacific equator have been cooler than usual. That's where we're at right now.

Even last fall, the long-term outlook suggested a return to neutral conditions by spring and potentially El Niño conditions by summer.

But there are some signs this may be happening faster than usual, which could accelerate the onset of El Niño.

Over the last few weeks, unusually strong bursts of westerly winds farther west in the Pacific -- where sea surface temperatures are warmer than average -- have been observed. There is a chance that this could accelerate the warming of those eastern Pacific waters and potentially push us into El Niño sooner than usual.

If we do enter El Nino by spring -- which we'll define as the period of March, April and May -- there are some long-term correlations with our weather here in Northeast Wisconsin.

Looking at a map of anomalously warm weather, most of the upper Great Lakes doesn't show a strong correlation, but in general, the northern tiers of the United States do tend to lean to that direction.

The stronger correlation is with precipitation. El Niño conditions in spring have historically come with a higher risk of very dry weather over that time frame, so this will definitely be a transition we'll have to watch closely as we move out of winter.