Glyphosate Resistant Giant Ragweed: To Me There Is No Doubt

One of my great farm management challenges is defeating “Giant Ragweed.” For those of you who don’t know “Giant Ragweed” is one of the toughest weeds to kill in Eastern Corn Belt soybean fields. Pictured here is “Ground Zero” for Giant Ragweed on my farm. I’m winning the war now with only a few showing up. The Giant Ragweed on the left hand side of the shot is untreated on an adjacent property, but a microcosm of what I’m up against.

Giant Ragweed has becoming resistant to Roundup or any other glyphosate in some parts of the Eastern Corn Belt. I’ve seen it for myself in southern Ohio, where beautiful fields of RR soybeans and corn have abundant towers of Giant Ragweed growing through them. So far in Ontario, this hasn’t been documented, but as I write I’m making the first claim. My fight against Giant Ragweed is because on my farm it comes through 2l/acre of glyphosate without even breaking a sweat.

Through the years certified crop consultants have said no, its because of something else. However, my own research tells me these Giant Ragweed are glyphosate resistant, partly because stem boring insects interrupt the flow of water translocation within the Giant Ragweed. They often get burned down to the ground, but spring back to life. That means I have to attack them with other chemicals such as First Rate and invariably the hoe. It is not an easy job. You heard it and seen it here first, glyphosate resistant Giant Ragweed in Ontario!

Soybean planting is over and what a cold stretch that was. Soybeans don’t like the cold weather and hopefully now that June has come it’ll get a lot warmer. We want no aphids and no rust going forward. We’ll see what happens.