Electric Weed Control Could Have a Fit in Blueberries

There is a lot of work to do to understand how to best use electric weed control in agricultural systems, but Marcelo Moretti, an assistant professor at OSU, believes the technology could have a fit in both organic and conventional blueberry production systems.

Marcelo Moretti, an assistant professor at OSU, displays electric weed control equipment at the OSU Blueberry Field Day in Aurora last summer. Moretti believes the technology could have a fit in both organic and conventional blueberry production.

The system isn’t exorbitantly expensive – he purchased the machine with which he is experimenting for $50,000. And it has shown promise wherever it has been tried.

“I think there is a fit for this technology in organic production systems and for controlling resistant weeds in conventional systems,” Moretti said.

Moretti recently launched a three-state, multiple-crop electronic weed control project in an attempt to determine just how feasible the technology can be. The project, which includes collaborators in New York and California, is being funded by a $2 million grant from the USDA Organic Agriculture Research and Extension Initiative.

“We would like to see what is the most cost-effective way to control weeds in not only blueberries, but apples in New York and organic almonds in California,” Moretti said.

The collaborators, Brad Hanson and Brittney Goodrich at UC Davis and Lynn Sosnoski from Cornell University in Ithaca, New York, will be working in blueberries, in addition to almonds and walnuts in California and apples in New York.

Moretti said the research is focusing on blueberries in part because the shallow rooted plants are a good test case. If they can survive the voltage necessary to kill weeds, then trees and other deep-rooted plants should also survive.

“Blueberries will be my model plant,” Moretti said. “If things go wrong, I will see it easier in blueberries than I would in a cherry tree, for example, which has deeper roots.”

In the project, researchers will be attempting to answer several questions, Moretti said. “We will be looking at which weeds are easier to kill, what time of year offers the best opportunities for weed control, how fast do you go, how many times do you need to do this, what is the impact on regrowth of perennial weeds, things as basic as that,” he said.

Controlling weeds with electricity is nothing new, Moretti said. “The first time they tried it was in the 1800s,” he said. The practice gained steam with some technological developments in the 1950s when researchers developed the first commercial unit, but never caught on.

“Maybe herbicides became too inexpensive,” Moretti said. “Nobody was looking to electric weed control. If there wasn’t this push for organic production, which has caused us to revisit mechanical weed control, there probably wouldn’t be a company looking to this now, either.”

The practice requires high voltage. The machine Moretti is using, a Zasso, has a 30k VA generator that will produce, depending on the setting, 240 volts and 30 amps.

“Once the electricity is in the plant, the amperage, or current, will move down the roots and heat the plant from the inside out, boiling it and killing it,” he said.

In tests to date, different weeds have responded differently, Moretti said. “The bigger the plant, chances are it will be harder to kill,” he said. “And grasses seem to be harder to kill than broadleaves.

“It could be because of their roots system or because they have a different leaf architecture that makes them not good at conducting electricity.”

Soil texture also can affect performance, he said, as it typically takes more voltage to kill weeds in soils with high organic matter than in sandy soils that have low organic matter.

Moretti first started looking into electric weed control as a means to help hazelnut growers battle resistant weeds.

In organic blueberries, he is looking to see if the technology can be used to complement weed mat or as a standalone approach to weed control.