Weed Madness

By: Agronomy Insider

How Resistance Spreads
Surprised at how a field full of herbicide-resistant weeds results? It had its origins years earlier. Birds do it, bees do it, even educated fleas do it, as the old Cole Porter song goes.

So why can’t waterhemp (or weeds) do it?

That last line probably isn’t funny if you’re battling herbicide-resistant weeds. Still, it says much about the way herbicide-resistant waterhemp infests your fields in the first place.

That field full of weeds – waterhemp, Palmer amaranth, marestail, or something else – started some time before.

Field Flirters
It’s akin to when a point guard catches a cute courtside TV reporter’s eye. Waterhemp is dioecious, with male and female plants. Sparks quickly fly.

“Since waterhemp is dioecious, pollen is already moving around,” says Pat Tranel, University of Illinois (U of I) weed scientist. “Pollen can be viable up to 120 hours, and it can move ½ mile from the pollen source.”