NC State Extension Publications

Introduction

Trade Name: Envoy Plus Common Name: clethodim Formulation: 0.94 EC

Uses

Postemergence control of labeled grass weeds in greenhouses, lathhouses, shadehouses, and around outdoor ornamentals, including nurseries, parks, Christmas or other tree farms, roadside plantings, and landscaped areas around buildings.

Amount of Active Ingredient Amount by Formulation
0.94 EC
Per Acre 0.066 to 0.24 lb 9 to 32 fl oz
Per 1,000 sq. ft. 0.2 to 0.73 fl oz

Major Weeds Controlled

Many annual and some perennial grasses such as barnyardgrass, crabgrass, crowfoot grass, foxtails, field sandbur, bermudagrass, johnsongrass, and quackgrass.

Major Weeds Not Controlled

Sedges and broadleaf weeds.

For Best Results

Apply to actively growing grasses that are not under environmental stress. Add a nonionic surfactant (containing at least 80 percent active ingredient) at 0.25% by volume to the spray solution (1⁄3 oz per gallon). Consult label for appropriate application timing for perennial grass control.

Cautions and Precautions

Unsatisfactory control may result if grasses are stressed by drought, temperature extremes, excessive water, or low humidity, or if grasses are not at the correct growth stage at the time of application. Do not cultivate treated grasses seven days before or seven days after application or control may be reduced. Do not apply a broadleaf herbicide within one day following Envoy application. Do not apply Envoy if rainfall is expected within 1 hour of application. Sugar maples cannot be tapped for syrup within one year of application. Do not apply more than 68 fluid ounces (0.5 pound active ingredient) per acre per season. Growers have reported some injury on Blue Ice cypress, Asiatic lily, Emerald arborvitae and Arizona cypress.

Residual Activity

No residual weed control should be expected.

Volatility and Leaching Potential

Little volatility. Clethodim is rapidly degraded through activity of microbes and exposure to sunlight. The chemical is only slightly adsorbed and has the potential to leach, but degradation is very rapid so the actual amount of leaching is probably slight.

Symptoms and Mode of Action

Slow acting herbicide; requires 7 to 14 days for control. Inhibits acetyl coenzyme A carboxylase, an important enzyme for many biosynthetic pathways. MOA groups: WSSA Group 1; HRAC Group A.

Herbicide injury symptoms factsheet

Additional Information

Worker Protection Standards REI: 24 hours
PPE: coveralls, chemical-resistant gloves and boots, eye protection
Manufacturer: Valent USA Corporation EPA Reg. # 59639-132

Author:

Professor of Weed Science, Extension Specialist & Department Extension Leader
Horticultural Science

Publication date: April 29, 2016

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