Hort Notes: Misconceptions about Superweeds, and a Tool for Managing Yellow Nutsedge

May 3, 2016

Dispelling Common Misconceptions about Superweeds

The Weed Science Society of America (WSSA) is a non-profit professional society that promotes research, education, and Extension outreach activities related to weeds; provides science-based information to the public and policy makers; and fosters awareness of weeds and their impacts on managed and natural ecosystems.

The term “Superweeds” has become of common news topic in recent years. The Weed Science Society of America (WSSA) suggests that some of the information being provided does not accurately represent the science behind the topic. In an attempt to increase the understanding of the term “Superweed”, WSSA has published a fact sheet dispelling common misconceptions on the topic. The Dispelling Common Misconceptions about Superweeds fact sheet can be found at: http://wssa.net/wp-content/uploads/WSSA-Fact-Sheet-on-Superweeds_16-Sep-2014.pdf

A Tool for Managing Yellow Nutsedge

Yellow nutsedge is a perennial weed present in many landscapes that is very difficult to manage with cultural practices. Dimethenamid is a preemergence herbicide that first received EPA registration for use in field corn. After many years of proving its value as a weed management tool, dimethenamid has made its way to use in turf and in the landscape. TowerTM received federal registration in 2007 and FreeHandTM in 2008, and Massachusetts registration in December 2007 and July 2008, respectively.

A dimethenamid only formulation, TowerTM is labelled for use in commercial ornamental production, landscape and turf, with 6.0 pounds of active ingredient per gallon formulation.

FreeHandTM combines dimethenamid and pendimethalin for a broader range of control, and is labelled for use in ornamental production and landscape. FreeHandTM is NOT labelled for use on cool-season turf. FreeHandTM is a 1.75G formulation.

A large number of landscape ornamentals are tolerant of both of these products, both of which control a large number of summer and winter annual weeds. TowerTM and FreeHandTM also provide another option in our seeming endless battle with yellow nutsedge. They are applied pre-spout for yellow nutsedge control - scout and determine the area where yellow nutsedge is problematic and treat those areas in the spring.

Product labels can be found at:

See pictures of yellow nutsedge here:

https://extension.umass.edu/landscape/weeds/cyperus-esculentus

- Randy Prostak