NC State Extension Publications

Introduction

Trade Name: Ornamental Herbicide II (OH2) Common Name: oxyfluorfen + pendimethalin Formulation: 3G (2+1)

Uses

Preemergence control of grasses and broadleaf weeds in container- and field- grown woody ornamentals. Not recommended for use in landscape plantings.

Amount of Active Ingredient Amount of Formulation Herbicide
2 + 1 lb (oxyfluorfen + pendimethalin)
Per Acre 100 lbs
Per 1,000 sq. ft. 2.3 lbs

Major Weeds Controlled

Several annual grasses and broadleaf weeds including large crabgrass, bittercress, groundsel, spurge, oxalis, dogfennel, cudweed, and prickly lettuce.

Major Weeds Not Controlled

Eclipta, doveweed, , perennial weeds and emerged weeds. Note: variable results on spotted spurge have been reported.

For Best Results

Do not incorporate physically. Irrigate immediately after application to activate the herbicide. Repeat application at two to three month intervals. Remove existing weeds before application.

Cautions and Precautions

Apply to dry foliage only. Even labeled ornamental species may be injured by OH2 if granules adhere to the foliage. If granules adhere to foliage it is important to remove them before irrigation. Shake plants or hand water immediately to wash the particles off the plant foliage. Do not apply to plants such as daylily, liriope, yucca, or Hosta with leaves that channel granules to the leaf base. Do not use in greenhouses. Not recommended for bedding plants, liner production beds, herbaceous groundcovers, flowers, turf, or plants bearing edible fruit. Do not use on Erica mediterranea (Mediterranean heather), Rhododendron spp. ‘Hinocrimson' and `Snow', Sarcococca hookeriana var. humilis, Euonymus alata `Compacta', or Potentilla fruticosa `Goldfinger'.

Residual Activity

In container nurseries, 6 to 12 weeks of weed control can be expected, depending on weed species, substrate, temperature, and irrigation practices. Bittercress control has been observed for 10 to 12 weeks but other species are typically controlled for 8 weeks or less.

Volatility and Leaching Potential

Low volatility and low leaching potential. However, do not apply in enclosed structures as volatilization is possible. In container nurseries, surface runoff may result when broadcast applications are employed since many granules fall between pots. Otherwise, the potential for leaching and surface runoff is low.

Symptoms and Mode of Action

Oxyfluorfen acts as a contact herbicide, disrupting cell membranes via a mechanism that requires light for activation. Pendimethalin inhibits root development by affecting cell division. See the descriptions for Goal and Pendulum for more details. Injury symptoms on ornamentals include contact-type burn where granules are trapped on the foliage and girdling at the soil line on some azalea cultivars. Oxyfluorfen: HRAC Group E; WSSA Group 14; Pendimethalin: HRAC Group K1; WSSA Group 3.

Additional Information

Worker Protection Standards REI: 12 hours
PPE: coveralls over long-sleeved shirt and long pants, chemical resistant footwear plus socks, chemical resistant gloves
Manufacturer: Everris EPA Reg. # 538185-178

Author

Professor of Weed Science and Extension Specialist
Horticultural Science

Publication date: Nov. 19, 2014

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