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
Center at Virginia Tech in
Tall fescue white clover, and buckhorn plantain control were assessed to fulfill these objectives.