You select your own enemy. That’s what David Kee, director of research at Minnesota Soybean Growers Association said about how weeds and other pests are combated in Minnesota.
Throughout the years, Kee has seen various weeds, such as the giant ragweed, common ragweed, kochia and water hemp, develop a resistance to herbicides and other methods that are used.
“I started seeing pesticide resistance in my career already in the 1980s,” Kee said.
But it wasn’t until 1996 when the herbicide RoundUp was introduced and became increasingly popular, that Kee knew it was only a matter of time before farmers would really experience the resistance effect.
That became even more evident in 2010 and 2011.
Resistance occurs when all weeds are not eradicated in one setting. It doesn’t take much to reoccur and is a part of the biological cycle. Regardless of what method is used to get rid of the weeds or pests, whatever survives, develops a resistance.
“Every time you do anything, whether you mow or hand blade, you’re selecting you’re enemy in the future,” he said.
Back in the day, the concern wasn’t so much about herbicide and pesticide resistance, but about Johnson grass and quack grass. The two types of grasses were quite resilient to plowing.
“Now we have to deal with herbicide and pesticide resistance on top of that,” Kee said.
One practice many may contribute to the resistance development is by using the same chemical for every crop, such as RoundUp Ready Sugar Beets, RoundUp Ready Corn and RoundUp Ready Soybean.
Regardless of what crop what crop was planted, the fields would still receive the same active ingredient in RoundUp, which is glyphosate.
In recent years, it’s been discovered that the insect soybean aphid has developed a resistance, as well, Kee said. The soybean aphid is considered to be the number one insect problem for soybean crop farmers.
“Herbicide and pesticide resistance is the result of the overuse of the compound in multiple areas,” Kee said.
But there are ways that a crop farmer can slow down the process of pests and weeds returning even more resilient, Kee said.
One way is to alternate techniques yearly. The other is to not use the same technique on each field, Kee said.
The first step in the process is to evaluate the situation, discover what the problem is and manage it.
Just rotating the crops, while using the same herbicide will only accelerate the resistance process, he said.
“But if you use a different herbicide, you will develop resistance much slower,” Kee said.
Kee recommends rotating techniques, as well as rotating the crops.
The Soybean Checkoff has dedicated years of education, research and promotion of the soybean and is investigating ways to combat resistance.