ARS | Publication request: Postharvest control of Russian thistle (salsola tragus) with a reduced herbicide applicator in the Pacific Northwest

Submitted to: Weed Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 20, 2007
Publication Date: March 1, 2008
Repository URL: http://hdl.handle.net/10113/43129
Citation: Young, F.L., Yenish, J.P., Launchbaugh, G.R., Mc Grew, L.L., Alldridge, J.R. 2008. Postharvest control of Russian thistle (salsola tragus) with a reduced herbicide applicator in the Pacific Northwest. Weed Technology. 22:156-159.

Interpretive Summary: Background: Russian thistle is a serious problem in the Pacific Northwest (PNW) where it infests about 4.45 million acres of cropland and costs growers more than $50 million annually for control measures, reduced crop yield, and inferior crop quality. After crop harvest, Russian thistle grows profusely, produces tremendous amounts of seed, and depletes the soil of moisture required for next year’s crop. Description: A 2-yr study conducted in the low-rainfall zone compared postharvest Russian thistle control; amount of herbicides used, and associated costs with a conventional broadcast sprayer and a light-activated, sensor-controlled sprayer. Russian thistle control was similar within each of two herbicide treatments regardless of sprayer with the best herbicide treatment controlling Russian thistle > 90%. Impact: The light-activated, sensor-controlled sprayer reduced the amount of herbicides used by an average of 42% and reduced herbicide cost of the most effective treatment up to $7.37/a compared to the conventional broadcast sprayer. The use of the light-activated, sensor-controlled applicator will provide excellent postharvest Russian thistle control while increasing farm profitability and environmental quality.

Technical Abstract: Russian thistle (Salsola tragus) is a severe problem in fields after crop harvest in the Pacific Northwest (PNW) and is controlled either by tillage or broadcast applications of various herbicides. A study was conducted in Washington in 2000 and 2001 at four sites to compare the efficacy of two herbicide treatments applied with a light-activated, sensor-controlled (LASC) sprayer and a conventional broadcast sprayer for postharvest Russian thistle control. Additionally, economic comparisons were made among herbicide treatments and application methods. Both herbicide applicators controlled Russian thistle similarly within each herbicide treatment. Weed control was unacceptable (< 75%) when glyphosate plus 2, 4-D was applied with either applicator. In contrast, Russian thistle control was > 90% with paraquat plus diuron regardless of applicator. The overall reduction in chemical usage was 42% with the LASC compared to the broadcast applicator when averaged over the four sites. Cost savings using 2007 prices for the LASC compared to the broadcast applicator ranged from $6.68/ha to $18.21/ha with the paraquat plus diuron treatment and averaged $13.27/ha less for the four sites. The use of the LASC for postharvest Russian thistle control can reduce growers’ input costs, increase growers’ profits, and improve environmental quality by reducing the amount and area of a restricted use chemical.