Herbicide Options for Bermudagrass Establishment By Kevin Bradley and Rob Kallenbach

As the time for sprigging bermudagrass approaches in Missouri, it is important for producers to consider the impact weed infestations can have on the success of these newly established stands.

Although established bermudagrass stands are often characterized by their thick, dense monocultures that outcompete most weed invaders, newly sprigged bermudagrass fields are particularly vulnerable to weed interference and competition. Plants emerging from sprigs are relatively intolerant of shading and weed competition, so severe weed infestations can result in significant stand losses. Some of the most common weeds that interfere with bermudagrass establishment include winter annual weeds like chickweed, henbit, field pennycress and early emerging summer annual grass and broadleaf weed species like common ragweed, giant foxtail and large crabgrass.

Diuron is one of the only active ingredients labeled for preemergence (PRE) weed control in sprigged bermudagrass. Diuron is available in several formulations (Diuron 4L, Diuron 400, and Diuron 80) and is ironically sold under the same trade name as the active ingredient. Diuron is sold by a variety of manufacturers, including Agriliance, Helena, Drexel, MANA and Helena. Diuron may be applied PRE in sprigged bermudagrass at 0.75 to 2.25 lbs active ingredient per acre (1.5 to 4.5 pts per acre of 4 lb/gallon formulations) after planting but before bermudagrass or weed emergence. Bermudagrass injury can occur as a result of a PRE Diuron application if sprigs are planted less than two inches deep.

Establishing a new stand of bermudagrass in spring using a sprig planter.Producers typically apply Diruon immediately after the sprigs are planted. Photo provided by Rob Kallenbach

Diuron may also be applied postemergence (POST) to sprigged bermudagrass before weeds reach about four inches in height. When applying Diuron as a POST treatment, rates should not exceed 0.75 lbs active ingredient per acre, and a non-ionic surfactant should be added to all applications. POST applications of Diuron are more likely to cause visible signs of injury to the emerged bermudagrass, but this injury is transient in nature and usually disappears after a short period of time. All Diuron treatments require a 70-day grazing restriction after application, so this should be considered before deciding to make a PRE or POST application of Diuron.

Some of the key weeds that Diuron will control include large crabgrass, common lambsquarters, common ragweed and some pigweeds. Each of these species seems to be particularly troublesome at the time of bermudagrass establishment, but the opportunity to eliminate grass weeds like large crabgrass is perhaps one of the greatest benefits that Diuron offers. In one of the few research studies that has been conducted on the use of Diuron at bermudagrass establishment, Smith and Martin (1992) reported approximately 80 percent control of large crabgrass at three months after treatment with 3 pts/A of Diuron.

Some 2, 4-D products are also labeled for use following bermudagrass sprigging. As there are a wide variety of products that contain 2, 4-D available, the specific label of the product in question should be consulted before applying 2, 4-D to any bermudagrass stand. Generally, the products that are labeled for use in sprigged bermudagrass can be applied at a rate of 0.5 to 1.5 lbs of 2, 4-D per acre after sprigging, but while broadleaf weeds are still small and actively growing. It is important to consider that 2, 4-D products will control most annual broadleaf weeds present at the time of application, but will not provide any appreciable degree of grass weed control.

Other herbicides that might be considered later in the season include Grazon P+D, Cimarron and Cimarron Max. Grazon P+D may be applied at a maximum rate of 1.5 pts per acre but only after bermudagrass runners have reached at least six inches in length. Additionally, Cimarron and Cimarron Max can be applied to bermudagrass two months after bermudagrass establishment.

Plateau (imazapic) was once utilized for the control of annual grasses in bermudagrass but is no longer available for sale over-the-counter to growers in Missouri. We have received several questions over the past few months about the potential use of Journey in bermudagrass. Journey is a new prepackaged herbicide mixture from BASF that contains the active ingredients imazapic (Plateau) and glyphosate. However, a close examination of the Journey label reveals that this product is not for use “on areas to be grazed or cut for hay.”

Kevin Bradley and Rob Kallenbach
Agronomy /Ag Ext-Plant Sciences
573-882-4039/ 573-882-2801