Nutsedge (Nutgrass) and Bermudagrass Control in Ornamental Beds
James A. McAfee, Ph.D.
Associate Professor and Extension Turfgrass Specialist
For years, two of the more difficult to control weeds in ornamental beds were bermudagrass and the sedges such as yellow and purple nutsedge (commonly known as nutgrass). While there were several pre-emergent herbicides that provided good control of annual grassy and broadleaf weeds, these herbicides had little if any affect on perennial grassy weeds and the sedges. Fortunately today there are some herbicides that will effectively control perennial grasses such as bermudagrass and sedges in ornamental beds.
Before discussing the herbicides for control of bermudagrass and sedges in ornamental beds, we need to discuss proper bed preparation and maintenance of ornamental beds. Weeds usually are a problem because the ornamental beds were constructed improperly or because they are not maintained properly. First, the beds need to be constructed so that they will drain properly and not stay wet too long following irrigation and/or rain. This means using the proper soil mix for good drainage as well as raising the beds so they can drain better. Most ornamental plants perform poorly when grown in wet soil conditions. Also, many of the weeds that occur in ornamental beds such as the sedges are encouraged by soils that stay too wet. Once the plants are established, apply a uniform covering of mulch over the bare ground areas of the beds. This mulch acts much like a dense stand of turfgrass in that it helps prevent light from coming in contact with weed seeds in the soil. Light is a necessary requirement for germination for many of the annual type weeds that occur in ornamental beds. Next, watch the application of irrigation to beds. Most people over water their ornamental beds which encourages weed problems and sets up conditions that are conducive to disease problems. Only water when the ornamental plants show signs of needing supplemental water.
At this time there are three herbicides that are labeled for perennial grassy weed control in ornamental beds. These are listed in table 1. It should be noted that these herbicides will also control annual grassy weeds as well as perennial grassy weeds. However, they do not control broadleaf weeds. As with all herbicide applications to ornamental beds, read the label carefully before applying any of these herbicides. Check for rate, timing and particularly for list of approved plant material. If any of the plants in the bed are not on the approved list, then do not use the herbicide.
While there are several good options for control of bermudagrass in ornamental beds, the options for control of sedges is some what limited. At this time, the preemergent herbicide metolachlor ( Pennant ) is labeled for the control of yellow nutsedge (commonly known as nutgrass) in ornamental beds. For post-emergent control of sedge, the herbicide imazaquin ( Image ) is labeled for purple and yellow nutsedge (commonly known as nutgrass). Be sure and check the imazaquin label carefully before application since the list of approved plant material is rather limited.
Table 1. Herbicides For Control of Bermudagrass in Ornamental Beds
Company Name Common Chemical Name Trade Name PBI/Gordon Fluazifop-P-butyl Ornamec Solaris Fluazifop-P-butyl Grass-B-Gon Dexol Fluazifop-P-butyl Grass Out Lawn & Garden Sethoxydim Poast Valent Clethodim Envoy