University of Missouri research is finding electrocution controls common annual weeds such as ragweed and cocklebur, and it may even control some common brush species in pastures.

“I have been surprised by some of these results we have seen in pastures,” says Kevin Bradley, University of Missouri Extension weed scientist. “It’s hard for me to come up with a lot of herbicides that are financially reasonable to kill some of these tough woody species that electrocution seems to be working on.”

Bradley has been studying weed electrocution using the Weed Zapper for the past three years, primarily in soybean fields. This year’s research looks at this non-chemical weed control option in pastures. So far, the results are promising.

Tackle weeds with new tech

Electrocution provides good control for both ironweed and thistles that are bolted. “The fact that it killed some brush species,” Bradley says, “gives me hope.”

Proof falls on the shoulders of MU graduate student Grant Coe of Shelbyville.

“We’re looking at it as an alternative to spraying weeds,” Coe says. “And we are looking at electrocution in comparison with some of the common herbicide treatments we see in pastures.”

During the fescue summer slump period of July and August, Coe traveled to cooperative farms across the state. There, he ran the Weed Zapper and collected data. The results will be presented during the winter MU Crop Management Conference, Dec. 6-7 in Columbia.

“We are just trying to figure out what this machine will kill and won’t kill,” Bradley adds. “It’s mind-boggling.”

Reduce seed-head production

This is not the only project associated with weed electrocution. Coe is also studying reducing seed heads with the same process.

Missouri is a top cow-calf state, which requires a lot of grazing. However, cattle can develop fescue toxicosis from grazing during seed-head development.

Electrocution was applied to tall fescue plants at different stages of development in the spring.

“We found that specifically doing this in the boot stage resulted in the greatest reduction of tall fescue seed heads,” Coe says. “We saw there was some difference, but not a huge difference between this and some of our common herbicide treatments for fescue seed-head reduction.”

He also found that with electrocution in pastures, there is a potential for yield loss. “There were definitely some yield reductions,” Coe adds. “But it could be that there may be an increase in forage quality. We will need to do more work with these samples over the winter to figure this out.”

“We would stop working with weed electrocution,” Bradley adds, “but we just keep learning stuff all the time. Every year, we learn something new.”

Tweak the Weed Zapper system

In 2022, the weed electrocution project focused on varying boom heights.

The results showed that when the Weed Zapper boom hit just the top of a 3-foot-tall waterhemp plant, the control was not the most effective.

“If we had that same 36-inch-tall waterhemp, and we have that boom down at 12 or 18 inches tall, we can get nearly 100% control,” Bradley adds. But at that level, it is likely to hurt the soybeans as well.

He hopes engineers can take the information and perhaps renovate the machine, allowing it to zap weeds between rows. “Or maybe the engineers will make this on a robot someday, an autonomous vehicle or whatever. But boom height matters," Bradley says.