Turf Weeds was developed to provide weed management information and newsearch reports to turfgrass managers.  This site contains information on weed identification, chemical and cultural management of weeds, and current topics relevant to weed management in lawns and professional turf.  Turf Weeds was created  by Dr. Shawn Askew, Assistant Professor of Turfgrass Weed Science at Virginia Polytechnic Institute & State University.
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Starting Over, Effectiveness of Glyphosate + Diquat for Turfgrass Renovation

Description:
Author:S. D. Askew, J. Derr, W. Barker, and J. Beam
Author Org:Virginia Tech
Date:02/27/2005
Presenter:
Conference:Virginia Turfgrass Journal
Location:
File Formats:
Abstract:

Glyphosate is the most common consumer choice for nonselective weed and total vegetation control in turf and ornamental industries.   However, consumers want products to act fast and provide rapid symptoms while maintaining long-term or complete weed control.   Other nonselective products such as paraquat, diquat, and glufosinate produce rapid symptoms but may not completely control perennial weeds (Gaussoin 2000).   Previously, turfgrass managers have used a mixture of glyphosate and pelargonic acid in an attempt to produce rapid symptoms while maintaining weed control equivalent to glyphosate alone.   Unfortunately, pelargonic acid was difficult to keep in suspension and often resulted in reduced weed control when mixed with glyphosate compared to glyphosate alone (Bradley et al. 2002; Pline et al. 2000).   This reduced weed control in glyphosate plus pelargonic acid mixtures was shown to depend on pelargonic acid rate (Chachalis et al. 2002; Pline et al. 2000).   A new approach to rapid symptom vegetation control in turf and ornamentals is a mixture of glyphosate + diquat (a member of the bipyridillium family). Glyphosate + diquat (G+D) produces necrotic symptoms quicker than glyphosate alone.   Mix rates must be optimized to prevent glyphosate antagonism, but diquat mixes easily with glyphosate and stays in suspension better than pelargonic acid.   Since diquat rate in a G+D mixture can influence rapid symptoms and long-term weed control, studies are needed to determine plant response to rates of G+D compared to glyphosate and glufosinate.   To that end, several research studies have been conducted at Virginia Tech’s Hampton Roads Research Station, Virginia Beach and the Turfgrass Research Center at Virginia Tech in Blacksburg.   Tall fescue white clover, and buckhorn plantain control were assessed to fulfill these objectives.


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