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