NC State Extension Publications

Introduction

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Trade Name: Regal O-O Common Name: oxyfluorfen + oxadiazon Formulation: 3 G (2 +1)

Preemergence weed control in container grown ornamentals, including conifer seedlings. Also labeled for use in field nurseries and landscape plantings. Particularly useful when one wishes to avoid the use of root-inhibiting herbicides.

Amount of Active Ingredient Amount by Formulation
3G
Per Acre 3 lb ai/A (2+1) 100 lb
Per 1,000 sq. ft. 2.3 lb

Major Weeds Controlled

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Many annual grasses and broadleaf weeds including annual bluegrass, goosegrass, bittercress, chickweed, willowherb, groundsel oxalis, horseweed, and others.

Major Weeds Not Controlled

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Nutsedges & other established perennial weeds. Weak on spurge, chickweed, pearlwort, eclipta.

For Best Results

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Apply before weed emergence or remove existing weeds before treatment. Apply to dry foliage. Irrigate immediately after application.

Cautions and Precautions

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Granules may adhere to wet or hairy leaves and cause injury. Do not apply to plants such as yucca, hosta, or daylily that have leaves that may funnel granules to the base. Do not use in greenhouses or on herbaceous ornamentals. Allow several weeks between application and covering for winter protection or shipping in an enclosed trailer. For use by professional applicators only, not for homeowner or consumer sale.

Residual Activity

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Eight to ten weeks of residual preemergence weed control may be expected, depending upon substrate, irrigation practices, and season. Shorter residual is to be expected in container crops compared to soil applications.

Volatility and Leaching Potential

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Moderate volatility and low leaching potential. However, do not use in enclosed structures as volatilization is possible.

Symptoms and Mode of Action

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Oxyfluorfen and oxadiazon are both contact-type herbicides affecting primarily shoot growth. Injury symptoms on ornamentals generally consist of contact-type burn where granules adhere to the foliage. Mode of action for both active ingredients: HRAC Group E; WSSA Group 14.

Additional Information

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Worker Protection Standards REI: 24 hours (longer in Christmas trees)
PPE: coveralls over long-sleeved shirt and long pants, chemical resistant gloves, footwear plus socks
Manufacturer: Regal Chemical Company EPA Reg. # 48234-10

Author

Professor of Weed Science and Extension Specialist
Horticultural Science

Publication date: Feb. 27, 2015

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