Saturated steam an organic weed killer

The Steam Weeder looks like a vacuum cleaner and sounds like an espresso machine, with a long hose and nozzle attached to a tractor-mounted boiler that superheats water up to 250 degrees.

Erik Augerson, a graduate research assistant for Oregon State University, recently demonstrated how the technology works during Blueberry Field Day at the North Willamette Research and Extension Center, steaming along rows of organic blueberries to control field bindweed.

As a weed management tool, Augerson said the Steam Weeder has shown promise, especially for organic growers. The saturated steam kills weeds by bursting plant cells, without frying woody mulch like flame weeding does.

Augerson, who is earning his master’s degree from OSU in horticulture, is part of a research team trying to develop a season-long organic weed management program for small berry growers, using steam in combination with other mechanical treatments and certified organic sprays.

“The organic berry industry in Oregon is having a lot of trouble determining what the best and most cost-effective form of weed management is for their systems,” Augerson told the Capital Press. “We’re just trying to increase the growers’ toolbox.”

The project is supported in part by a $500,000 grant from the USDA Organic Transitions Program, with additional funding from the OSU Agriculture Research Foundation and Northwest Center for Small Fruits Research.

Jeremy Winer, managing director of Weedtechnics, the Australian company that manufactures the Steam Weeder, was also on hand at Blueberry Field Day to meet with growers and answer questions about the product.

According to Winer, the Steam Weeder superheats water and flashes it into saturated steam within the nozzle system. It sprays 2.5 gallons per minute, penetrating 1 inch deep into the soil.

“It’s not actually boiling, but it’s superheated,” Winer explained. “It explodes the (weed) cells.”

OSU purchased the Steam Weeder over the winter, and field trials began about a month and a half ago. While they are still collecting data, Augerson said the technology could be another option for organic growers.

“We know that it can kill weeds, and that it works from a management standpoint,” Augerson said. “I think it has a lot of promise.

Depending on the size and model, Steam Weeders cost between $16,000 and $30,000. Augerson said the value for small farmers is in decreased need for manual labor controlling weeds, allowing them to put their workers to better use.

“There is a lack of farm labor, and it is decreasing,” Augerson said. “We want to make it so farmers can utilize their labor in different ways.”

Augerson said they will need at least two years of data before they can start writing a comprehensive, full-season weed management program for organic berries.