Experienced golf turf managers in northern states have little trouble identifying and controlling crabgrass. They know when and where to apply preemergence herbicides and have a safety net of effective postemergence products to control any crabgrass that breaks through the preemergence barrier.
Unfortunately, northerners often overlook the occasional goosegrass infestation or mistakenly identify it as funny-looking crabgrass on steroids. They don't realize something is amiss until their ace-in-the-hole crabgrass treatment, quinclorac, has no effect.
Goosegrass thrives in wet, compacted soil where there is little competition from turf. It was frequently seen in worn areas of practice tees and along the borders of cart paths during a surprising number of Course Consulting Service visits throughout the Chicago area over the past two weeks. Goosegrass looks like crabgrass but has flattened stems, a white or silver center and a telltale zipper-like pattern of seedheads.
The key to preventing an occasional goosegrass problem from becoming a chronic concern is accurate identification and immediate action. A single goosegrass plant can produce up to 50,000 seeds, so it isn't in your best interest to simply wait until the first hard frost ends its life. Seeds germinate during spring, about two to four weeks later than crabgrass or when soil temperatures reach 63 to 65 degrees Fahrenheit. Goosegrass seed will continue to germinate under favorable conditions throughout summer, so an early season treatment of crabgrass preemergence herbicide will likely run out of gas before goosegrass seeds are finished germinating.
What are your options for control? Right now, most northern courses only have an occasional outbreak of goosegrass, so do your best to keep it that way. If you have a serious infestation, map affected areas and target them for sequential applications of preemergence herbicide next spring. A useful review of current chemical and cultural control options for goosegrass has been published by the University of Tennessee.
Culling out goosegrass by hand is a laborious but effective option. You need a keen eye and a sharp pocketknife to remove small weeds. Those unfamiliar with goosegrass won't notice the problem until the plants are huge, and by then a keen blade may be your only option.
The herbicide Pylex™ will do a great job controlling goosegrass in Kentucky bluegrass roughs. However, if you don't identify the problem early, golfers will be looking at big, dead clumps of stark-white goosegrass for many weeks until the plants finally decompose. Many superintendents ultimately remove Pylex-treated goosegrass plants by hand from tees because they can't stand to look at them any longer. If that is going to be the end result, why not just remove the weeds by hand in the first place?
Practice tees are the most common places to find goosegrass. They also are the easiest places for it to get out of control. Make an extra effort to cull goosegrass from practice tees, because you can't depend on a preemergence herbicide to remain effective under an onslaught of deep divots.
Be sure to follow the label recommendations closely if you decide to try Pylex on a creeping bentgrass tee or fairway. The current label recommends testing the product on a small area first because bentgrass is only marginally tolerant to Pylex at a reduced rate of 0.25 ounces per acre. Again, if you don't catch the problem early, why risk herbicide treatment when you will likely decide to remove the dead plants by hand anyway?
Don't dismiss the low-tech option of manually removing goosegrass from tees, especially when you only have a small, isolated infestation. Diligence, persistence and a stout blade will pay dividends.
Central Region Agronomists:
Bob Vavrek, regional director – email@example.com
John Daniels, agronomist – firstname.lastname@example.org
Zach Nicoludis, agronomist – email@example.com