The reason, is because many of the targeted weeds found in fields have been able to build up resistance to those herbicides.
Iowa State University Extension crops specialist Joel DeJong says crop protection chemical companies have not been able to introduce a new line of herbicides since the 1980’s. “It’s kind of scary, because we’ve had lots of new products on the market, but they are all from the same families that already existed. And because of that we kind of keep going back to the well and using the same ones, and if one works, we use it really hard,” DeJong says. “We’ve done that over time. Glyphosate, Roundup, worked extremely well and it still works extremely well on most weeds. However, there is one or two families of weeds in the state of Iowa that have really found a way to move around how glyphosate works — so they are now becoming more resistant to it. ” He says water hemp is one of the weeds that’s built that resistance.
Iowa State University Extension and Outreach are hosting a series of “Weeds Week” seminars at locations through out the state this week. DeJong, and his fellow Iowa State University Extension crops specialists, will lead the discussion of what farmers can do to help reduce the resistance level of weeds.
He says they are also going to do some activities and plan for the future on things that can be done differently. DeJong says even if crop protection companies were able to develop a new line of herbicide, it couldn’t be used right away.
“To pass all the hoops and everything else to make sure it is safe to the environment, and to people and to animals, it would take at least decade before that would be come available to the market,” DeJong explains. “So right now we’ve got to figure our how are we using the tools that we’ve to, how do we use them better, how do we reduce the risk of maybe developing more resistance in our weeds,” DeJong says. He says that’s what they are trying to do with their “Weed Week” information.
By Dennis Morrice, KLEM, Le Mars