Photos and Videos

Research on Saturated Steam for Field Bindweed Management


The equipment is a gasoline-powered pump and a diesel boiler mounted on a single axel trailer. At 1 mph, the steamer converts 3.3 gallons of water to saturated steam per minute. Saturated steam is water heated to above boiling (250 °F), but held under pressure so that it remains liquid. The nozzle temperature of this steam is about 180-190 °F. Steam treatment of weeds is a time vs. speed trade-off. At this time, we recommend 1 mph with a single application delivering the equivalent of 729 gallons of steam per acre in a broadcast application; Because organic blueberries are often grown with syntethic mulches or weedmat, we are treating the portion of field next to the weedmat (about 1/3 of the field.) Research to determine optimal steam rate, or operational speed, for weed control is an emphasis of this research.

Bindweed one week after saturated steam application.

Dr. Marcelo Moretti (right) and graduate student Erik Augerson (left) demonstrated their steaming technology at the 2018 Blueberry Field Day, North Willamette Research and Extension Center, Aurora OR. 

Weeds in commercial blueberry in Oregon’s Willamette are commonly managed with weed mat. However, field bindweed and other weed species can come up at the edges. Here, a medium-sized cone concentrates saturated steam at the edge of the weed mat. Steam application does not damage the mat. Cones come in a range of sizes.

Weeds following steaming.PNG Weeds following steam treatment. Some of these, such as dandelions, will come back, because the soil protects roots from steam exposure. Annual weeds are more sensitive than perennials; any weed is more sensitive in the first year after its seed germinates.

Research on Biocontrol for Field Bindweed Management

Field bindweed regrows after application of contact herbicides. While frustrating, this may provide opportunity for timed applications of integrated management techniques.

Bindweed moth larvae look similar to cutworms but have had extensive host range testing to ensure they do not feed on any plant outside of the Convolvulaceae family. This species has been a USDA-APHIS approved biocontrol agent since the early 1990’s.

Field tests of attractant formulations will help us determine if bindweed moth herbivory can be focused, and used as a push-pull strategy.

A technician releases larvae onto a patch of bindweed in a commercial organic blueberry field. Management is particularly difficult in this setting because bindweed grows over and through weed matting.