Doing what other herbicides can't in cool-season grasses
By Dean Mosdell, Ph.D., technical services manager for Syngenta Tenacity® herbicide
is a systemic herbicide for pre- and post-emergence control of grass and broadleaf weeds in several cool- and warm-season turf species. The active ingredient, mesotrione
, is based on a naturally occurring compound produced by the bottlebrush plant (Callistemon citrinus
). Tenacity is a HPPD (p-hydroxyphenylpyruvate-dioxygenase) inhibitor that prevents the formation of carotenoids in susceptible plant species. Without carotenoids, light energy and by-products of photosynthesis destroy chlorophyll and cell membranes, resulting in bleaching of leaves and plant death.
Certain grasses like bentgrass (Agrostis spp
.), nimblewill (Muhlenbergia spp.
) and windmillgrass (Chloris spp
.) are sensitive to Tenacity. Multiple applications can selectively remove these grasses from Kentucky bluegrass, tall fescue and perennial ryegrass. Coupled with a re-seeding program, turf areas can be converted to the desirable turf species.
It is recommended to apply Tenacity at 4-5 oz./A on a two- to three-week interval for three applications. Seeding can occur after the second application of Tenacity. Depending on location, applications of Tenacity starting in August or early September will best coincide with a re-seeding program for optimum turf conversion.
Below is a summary of Tenacity trials from across the U.S. over several years.Trial sources: Illinois, Indiana, Iowa, South Carolina, Virginia and Washington, 2005-2007.
For more information about bentgrass control, contact your local Syngenta territory manager
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