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Resistant weeds expand in Wisconsin – Audio

Resistant weeds expand in Wisconsin - Audio

Vince Davis, Extension Agronomist
Department of Agronomy
UW-Madison College of Agricultural and Life Science
Phone: (608) 262-1392

2:58 – Total Time
0:16 – Tough weeds expand in state
0:41 – Two new weeds herbicide resistant
1:11 – How farmers may cope
1:31 – Expanding in the state
2:21 – Can spread fast
2:35 – Web site for more information
2:49 – Lead out

Sevie Kenyon: Some very tough weeds have entered that state of Wisconsin. We are visiting today with Vince Davis, Department of Agronomy University of Wisconsin Extension in the College of Agricultural and Life Sciences, Madison Wisconsin, and I’m Sevie Kenyon.

Sevie Kenyon: Vince we have some very tough weeds out there, what’s going on?

Vince Davis: The biggest challenges we have that are new to the state are pigweed species, particularly waterhemp and Palmer’s amaranth that we are seeing a lot more of and waterhemp has been in the state for quite a while but hasn’t been all that problematic. Where Palmer is actually a newer weed to Wisconsin but has been very problematic to production systems in the south.

Sevie Kenyon: What’s new about these two weeds?

Vince Davis: The biggest thing about these two weeds is they develop herbicide resistance fairly quickly and once they have herbicide resistance they’re very competitive in crop production situations. Right now we have confirmed recently both multiple populations of waterhemp that is resistant to glyphosate, or Roundup, as well as a population of Palmer’s amaranth in Dane County resistant to Roundup.

Sevie Kenyon: what kinds of things can a farmer do to minimize these issues?

Vince Davis: There are a number of things to integrate the system like crop rotation and incorporating tillage where appropriate, but the number one thing we need to do is change up the herbicide chemistries so we reduce the selection pressure on these populations.

Sevie Kenyon: Vince, where are these resistant weeds located in the state so far?

Vince Davis: So far Palmer’s amaranth is a fairly new addition to the state and our first confirmation was in Dance County in 2013. And last year in 2014 we found some additional fields in Iowa County. So, so far that weed has only been confirmed in Iowa County and Dane County. Waterhemp on the other hand is becoming quite widespread throughout the state. Actually the two counties we have confirmed populations with glyphosate resistance is in Pierce County and Eau Claire County, but we are investigating multiple populations from all over the state to also have resistance to both glyphosate and PPO inhibiting herbicides.

Sevie Kenyon: And when you say these weeds can take over a field fast how fast do you mean?

Vince Davis: One female plant can produce almost a million seeds. In just a couple short years they can really go from being a handful of escapes in a field to being very very widespread.

Sevie Kenyon: Vince if people need more information, what do they do?

Vince Davis: The best thing to do is visit a website called so Take Action on and there are many fact sheets there to help with the management of these weeds and other resistant weed species.

Sevie Kenyon: We’ve been visiting with Vince Davis, Department of Agronomy, University of Wisconsin Extension, in the College of Agricultural and Life Sciences, and I’m Sevie Kenyon.