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United States Department of Agriculture

Agricultural Research Service

Title: New Potato Herbicide to Be Registered in 2004

Authors
item Boydston, Rick
item Hutchinson, P - UNIV OF IDAHO, ABERDEEN

Submitted to: Potato Country USA
Publication Type: Popular Publication
Publication Acceptance Date: February 1, 2004
Publication Date: March 1, 2004
Citation: BOYDSTON, R.A., HUTCHINSON, P. NEW POTATO HERBICIDE TO BE REGISTERED IN 2004. POTATO COUNTRY USA. 2004. p. 6-7.

Interpretive Summary: Nightshade and other broadleaf weeds continue to present problems in potato crops, despite several herbicides registered for these weeds in potatoes. Sulfentrazone, a new preemergence herbicide, is expected to be labeled for use on potato in the 2004 growing season. Sulfentrazone use in potato will be restricted to preemergence applications. Susceptible weeds die as they begin to emerge or shortly thereafter. Being a different mode of action than currently labeled potato herbicides, growers can utilize sulfentrazone to help manage herbicide resistant weeds, including triazine resistant lambsquarters and pigweed and ALS resistant kochia. Sulfentrazone is particularly strong on pigweed and nightshade species (hairy, black, and cutleaf nightshade) and suppresses yellow nutsedge. Several other key weeds that sulfentrazone controls are common lambsquarters, Russian thistle, kochia, smartweed, and common groundsel. Idaho and Washington researchers have tested sulfentrazone on six major potato varieties grown in the PNW; Russet Burbank, Ranger Russet, Russet Norkotah, Shepody, Bannock Russet, and Alturas. None of these varieties exhibited sensitivity to sulfentrazone, but potato injury is possible on low organic matter, sandy soils when sulfentrazone rates exceed that needed for weed control. Sulfentrazone use rates should be adjusted according to soil texture, organic matter, and soil pH. Sulfentrazone herbicide will not be allowed on soils classified as sand with less than 1% organic matter. Sulfentrazone is moderately persistent in the soil and can injure sugarbeets if planted within 24 months after application. Plantback interval for other crops varies depending on species sensitivity.

Technical Abstract: Sulfentrazone is expected to be labeled for use on potato in the 2004 growing season. Sulfentrazone use in potato will be restricted to preemergence applications as the herbicide is taken up through roots and shoots of germinating weeds. Sulfentrazone offers a new mode of action for potato growers. Sulfentrazone controls weeds by inhibiting an enzyme involved in chlorophyll synthesis, ultimately destroying cell membranes of susceptible weeds. Being a different mode of action than currently labeled potato herbicides, growers can utilize sulfentrazone to help manage herbicide resistant weeds, including triazine resistant lambsquarters and pigweed and ALS resistant kochia. In research trials, sulfentrazone was particularly strong on pigweed and nightshade species (hairy, black, and cutleaf nightshade) and suppressed yellow nutsedge. Several other key weeds that sulfentrazone controls are common lambsquarters, Russian thistle, kochia, smartweed, and common groundsel. Delaying application of sulfentrazone just prior to potato emergence will extend the weed control until about row closure. Ground and aerial applications should be incorporated with sprinkler irrigation or rainfall within 7 days of sulfentrazone application. Sulfentrazone has been tested on six major potato varieties grown in the PNW; Russet Burbank, Ranger Russet, Russet Norkotah, Shepody, Bannock Russet, and Alturas. None of these varieties exhibited sensitivity to sulfentrazone, but potato injury is possible on low organic matter, sandy soils when sulfentrazone use rates exceed that needed for weed control. In soils with pH above 6.6, the sulfentrazone becomes negatively charged and becomes more readily available for plant uptake. In those soils, sulfentrazone rates need to be reduced to account for increased herbicide availability the weeds and crop. Sulfentrazone is also more available for plant uptake in soils containing low amounts of organic matter, so herbicide rates should be lowered accordingly.

Last Modified: 4/18/2014
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