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Goosegrass Control

by John C. Fech and Roch E. Gaussoin

Goosegrass is a tough, troublesome weed. Photos courtesy of John Fech.

Goosegrass has many distinct features that make it relatively easy to identify. Goosegrass has dark green leaves that grow on stems that become white toward the base. The leaf blades are folded in the bud, about .25 inch wide and taper to a point. The ligule is membranous, toothed and divided at the midrib. Generally, goosegrass is devoid of auricles. The sheath is light green on the upper parts and becomes white at the base. The sheath is flattened, with a few long, white hairs near the collar. The root system is shallow and fibrous. The seed head is divided into finger-like segments, but thicker and more robust than crabgrass. The segments are often described as zipper-like. If not mowed, seed heads grow to be 4 to 8 inches long. Many other plants in the landscape have features that are descriptive of their names, particularly ones with distinct colorations. White poplar, yellow twig dogwood, red maple and silver maple are examples of these. The white coloration on many of the plant tissues is responsible for goosegrass’ other name, a nickname of sorts, “silver crabgrass.”

Growth habit

The stems of goosegrass are thick and grow low to the ground. These prostrate stems have several basal tillers that radiate from a common growing point. This low-growing habit allows it to persist and thrive under low heights of cut, as the majority of the leaf tissue remains after mowing. One of the most effective control methods is mowing, which works quite well for some weeds, such as shepherd’s purse, that have an upright growing habit, but not so well for goosegrass and prostrate knotweed.

Favorable growing conditions

The growth habit and the structure of goosegrass are features that allow it to grow well on tees and low-cut fairways and, in some cases, on greens. These attributes provide goosegrass with the necessary adaptation to these golf course locations.

Due to heavy foot traffic, the soil on most tees tends to be compaction prone. Plants with a shallow, fibrous root system, such as goosegrass, can tolerate compacted soils better than others that prefer a loose, fertile growing medium. There is no evidence that goosegrass prefers compacted soils, rather that it simply outcompetes other plants when soil particles are excessively compressed. It has been speculated that plants like goosegrass have a competitive advantage in compacted soils because they can tolerate lower oxygen levels.

Another consideration is that because compaction and wear occur concurrently in trafficked areas, it is difficult to determine which is more problematic. Each can be damaging on their own, as well as the combination of the two. Clear research procedures are needed to examine their separate effects. Arguing the point may be of academic interest, but loses practicality in the real world.

Most weeds favor open, thin turfs. Goosegrass is no exception. Due to divots being taken, diseases, insects and other injuries, tees and fairways are sometimes not as thick as desirable. Taking advantage of these openings, goosegrass germinates readily once the soil temperature is consistently in the 60 to 65-degree range. Germination may continue all season until temperatures cool in the fall.

Tees are common locations for goosegrass, as they are subject to wear.

Cultural control

Many integrated pest management (IPM) techniques are reasonably effective in suppressing or eliminating populations. Mowing height, for example, is particularly effective at reducing the population of crabgrass in fairways. This is evident at fairway edges, where a higher cut produces a canopy of plant tissue that shades the soil, making the soil surface less conducive for crabgrass germination.

Unfortunately, most IPM techniques are not highly effective for goosegrass control. Even so, the following will provide benefits and a more competitive growing environment for desirable turfgrasses.

Overall, turf management practices that reduce soil compaction and excess soil moisture and that maintain healthy turf will minimize goosegrass infestation.

Fertilization: Turfgrass species such as bermudagrass and perennial rye are relatively rapid growing grasses, and respond favorably to increased fertilization. One pound of nitrogen per 1,000 square feet per growing month helps regrow turf canopy into areas damaged by traffic. Of course, these nitrogen rates can produce the negative side effect of very succulent tissue, which tends to be more susceptible to foliar diseases like leaf spot. Keep this in mind as you increase turf fertility in an attempt to control goosegrass.

Irrigation: Adequate to excessive moisture in the upper inch of soil is required for the germination of goosegrass. Reductions in the frequency and amount of irrigation water can limit germination, but because the root systems of desirable turfs are also shallow, it is difficult to create a soil medium that is too dry for goosegrass germination, yet supports the vigorous growth of turf. In all situations, uniform irrigation distribution should be achieved to avoid having areas that are too dry or too wet.

Traffic: The areas where goosegrass is most commonly located on golf courses are exposed to frequent vehicular and foot traffic, which results in soil compaction and wear. Core aeration will alleviate compaction if performed on a regular basis. Turf wear can be decreased by diffusing and avoiding traffic, especially after rainfall.

Timing of seeding in spring: Because perennial ryegrass will germinate at a cooler temperature than goosegrass, a short window exists in spring to allow establishment of desirable turf before goosegrass is favored. This is a tricky technique to use, as both species are encouraged by moist growing conditions. Seeding of cool-season grasses after soil temperatures consistently reach the 60 to 65-degree range should be avoided in areas with a history of goosegrass infestation.

Physical/mechanical removal: Hand-weeding, where roots are cut below the ground to avoid disturbance of the surface appearance, can be utilized on special occasions, such as before tournaments. Though not practical for large areas, it is useful in controlling mature goosegrass plants.

Chemical control

A number of preemergent herbicides are available for goosegrass control and should be made in late winter or early spring when soil temperatures reach 60 degrees for 24 consecutive hours. Postemergent control is dependent on turfgrass species and will require repeat applications of herbicides for successful management of goosegrass. Do not assume, however, that if it works for crabgrass it will work for goosegrass. Dithiopyr can provide adequate control of goosegrass. Under hot, dry conditions, most dithiopyr formulations may volatilize, making irrigation or timely rain critical to acceptable performance. In bermudagrass, goosegrass may be controlled by postemergent application of an arsonate herbicide (DSMA, MSMA, CMA) mixed with metribuzin or diclofop. The future of MSMA is not guaranteed. Postemergence control in bermudagrass may be obtained with formasulfuron or trifloxysulfuron.

In cool-season grasses, postemergent control options are limited to fenoxaprop-ethyl and arsenical compounds. Recently, sufentrazone has shown promise on goosegrass with evidence of good to excellent control.

John Fech is an extension educator specializing in turf and ornamentals at the University of Nebraska-Lincoln. Roch Gaussoin is a professor of horticulture and extension turf specialist at the University of Nebraska-Lincoln.