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Postemergent Herbicides for Use in Ornamentals1

Jeffrey G. Norcini and Chris Marble 2

Introduction

Postemergence herbicides are herbicides that are applied with the goal of controlling weeds after emergence (germination). This publication was written for nursery growers and landscape pest control companies to provide information on postemergence herbicides labeled for use in and around ornamental plants.

Postemergent herbicides are applied directly to weeds. These herbicides are most effective when the weeds are small and actively growing. Effectiveness of these herbicides generally is reduced if the weeds are under stress. If perennial weeds are large, try spot applications of a translocated herbicide in late summer or early fall. The herbicide usually must remain on the plant several hours to be effective. The length of time the herbicide needs to stay on the plant before being washed off is called "rainfastness"; this is the amount of time the herbicide needs to adequately dry or be absorbed by plant tissues (check the label, as the time can vary). Therefore, be sure the herbicide isn't washed off by rain or a sprinkler within the specified period.

Some postemergent herbicides can be applied over the top of ornamental plants. The herbicides listed in Table 1 can be safely used over the top of some ornamentals when used according to label directions.

Table 2 lists postemergent herbicides that are registered for use around ornamental plants when applied as a directed spray. When using these herbicides, be sure that the herbicide does not contact desirable vegetation. Use of a shielded spray nozzle or wick applicator is recommended when applying these types of postemergent herbicides in the vicinity of ornamentals or turf.

Tables

Table 1. 

Postemergence herbicides that can be applied over the top of tolerant ornamental species. "X" indicates that the herbicide can be used for this location. This table lists registered pesticides that should be integrated with other pest management methods. Contact your local UF/IFAS Extension office for additional information (https://ifas.ufl.edu). Contact: Weed Specialist (marblesc@ufl.edu). Table 1.

Table 2. 

Postemergence herbicides that can be applied as directed sprays. "X" indicates that the herbicide can be used for this location. This table lists registered pesticides that should be integrated with other pest management methods. Contact your local UF/IFAS Extension office for additional information (https://ifas.ufl.edu). Contact: Weed Specialist (marblesc@ufl.edu).

Footnotes

1. This document is ENH95, one of a series of the Environmental Horticulture Department, UF/IFAS Extension. Original publication date November 1993. Revised March 1999, November 2014, December 2017, and March 2021. Visit the EDIS website at https://edis.ifas.ufl.edu for the currently supported version of this publication.
2. Jeffrey G. Norcini, former Extension specialist, UF/IFAS North Florida Research and Education Center; and Chris Marble, assistant professor, Environmental Horticulture Department, UF/IFAS Mid-Florida REC; UF/IFAS Extension, Gainesville, FL 32611.

Mention of a commercial or herbicide brand name or chemical does not constitute a recommendation or warranty of the product by the authors or UF/IFAS, nor does it imply approval of the product to the exclusion of other products that may also be suitable. Products should be used according to label instructions and safety equipment required on the label and by federal or state law should be employed. Pesticide registrations may change, so it is the responsibility of the user to ascertain if a pesticide is registered by the appropriate state and federal agencies for its intended use.

Publication #ENH95

Date: 4/11/2021

RELATED TOPICS

  • Program Area: Integrated Pest Management
Management

Contacts

  • Stephen Marble
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