Masquerading goosegrass

Bob Dluzen
Special to The Detroit News

 Just before our first hard frost, I spotted some grassy weeds growing along the edge of a garden I tend. From a distance, they looked a lot like crabgrass plants, but looking closer I could tell they were something different. They were instead, a similar looking weed called goosegrass. It's easy to confuse the two, even long time turfgrass people will mistake it for misshapen crabgrass. Even though the two weeds look similar, they are two entirely different species.

Goosegrass and crabgrass have a similar growth habit making a circular pattern or rosette with a growing basal point or bud in the center of its crown. Goosegrass however, has flattened stems as opposed to the round stems of crabgrass.

Goosegrass has flat stems that grow from the center of the plant. Its seeds are arranged in a chevron pattern along the seed stalk. By the end of the growing season, the plant has produced many tillers, or offshoots, as can be seen here.

Goosegrass is often found in the least desirable growing conditions where other grasses are unable to grow, especially areas that have damp, compacted soil. Those soil conditions are tough on most plants but goosegrass is not bothered by that. In fact, they will flourish due to the lack of any competing grasses.

Pathways, driveway edges, or places where cars frequently drive over the lawn will often have a lot of goosegrass growing.

Golfers may notice it on cart paths, practice tees and other areas with lots of foot traffic. It can also infest golf greens since it can grow and thrive under the extremely short mowing of greens.

It’s also a problem in some horse paddocks since  horses would rather not  graze on goosegrass if other grasses are around.

Goosegrass is an indicator that your soil minerals may be out of balance and may be low in calcium and phosphorus but high in potassium. A soil test will determine if that’s the case or not.

The plants I found had just finished maturing and were ready to drop their seeds. They grow all summer long and hard frost is the only thing that will stop them from growing. That makes them a true annual plant in our area.

It’s a good idea  to identify them in the fall since that’s when their seeds are dispersed. Each plant can produce thousands if not tens of thousands of seeds each growing season that can persist in the soil for years. Those seeds lie dormant in the soil during the winter until spring temperatures warm the soil.  When soil temperatures reach the mid-60s, the seeds germinate and start new plants. Because goosegrass needs warmer soil than crabgrass, they germinate a few weeks later than crabgrass. So even though a crabgrass herbicide theoretically could stop them from growing, it’s unlikely that an application of crabgrass herbicide will still be around in the ground for that long to take care of the goosegrass. What happens with herbicides is over time, bacteria in the soil breaks down herbicides into inert molecules allowing goosegrass to evade the herbicide.

Due to its relatively late germination time, goosegrass is classified as a warm season weedy grass. Also, seeds will continue to sprout all summer long and even late started plants are able to produce seeds, just the plant itself will be smaller.

In most cases the best solution to control goosegrass is to remove the basal growing point in the crown. Any kind of sharp knife or pointed garden tool will do the job. Fortunately, unlike some other kinds of weeds, they are easy to control that way. Dandelion weeders such as a weed hound or similar tool  work perfectly fine and can be used standing up instead of crouching down with a knife. Even many greenskeepers prefer the manual removal of goosegrass as opposed to chemical control, especially if done regularly even if it is labor intensive. But like any weed control, getting them when they're small is a lot easier than putting it off until they’re big and tough.

In lawns, the best way to control it is to keep your grass tall. Remember how it grows so well on golf greens? Well, mowing goosegrass short will not do a thing to it. Instead, keeping your lawn grass at a height of 3 to 5 inches will pretty much guarantee that goosegrass will never get a foothold. Taller mowing is better for the all-around health of your lawn grass anyway.

Many years ago, I was responsible for an expansive lawn and kept the mowing height at least 5 inches. Once I got the broadleaf weeds under control along with occasional deep irrigation, timely fertilization and sharp mower blades, it was an amazing lawn that received plenty of ooh’s and ah’s whenever visitors stopped by. Guests never failed to ask if they could walk over it.

The excessive rains we had this past growing season caused more soil compaction than usual because gardeners had to get to their gardens before their soil adequately dried out enough. Damp soil compacts much more easily than drier soil. Those two things added up to ideal growing conditions for goosegrass.

Keep an eye out for it later this coming spring. If you do find it, take steps early to correct the conditions that caused it to appear.