Goosegrass, or Eleusine indica, sometimes called silver crabgrass, is a very problematic weed in closer mowed turf and in warmer regions in the country. I have only noticed it twice in Northeast Ohio, but that just tells me that it is here.
Some of the identifying factors that will give it away are the seedhead, which appears zipper-like, and the color of the center of the plant, which appears bright white or silvery. Once you detect either, it is easy to identify. It is folded in the vernation and tends to have a flattened or prostrate growth habit. Seedheads will be in a herringbone pattern.
Goosegrass, like crabgrass, is a summer annual in Northeast Ohio. The biggest difference is timing of germination. Crabgrass will germinate when the soil dwells in the 50 to 55 F range at a depth of two inches, and Goosegrass will be later. These seeds will germinate when the soil remains in the 60 to 65 F range.
This is important to note with regards to pre-emergent herbicide timing. It thrives in compacted areas where turf cover may be thin. This also may be an indicator that the area should be aerated. The flattened growth pattern and ability to tolerate lower mowing heights make it a problem on golf courses and sports fields. The only time that I dealt with it on a golf course was at tee height.
The typical approach to management consists of a good pre-emergent program. The problem arises in lawn care where herbicides may be applied earlier in the year and barrier breakdown occurs prior to germination. Often, sequential applications are not made, and later germinating weeds can survive. Additionally, where goosegrass prefers to grow in those thinner turf areas, herbicides tend to be broken down quicker due to sunlight penetration.
Control strategies start with maintaining a healthy stand of turfgrass. Higher mowing heights, routine aerification, and deep, infrequent irrigation practices will all decrease the pressure from goosegrass.
Incorporating a pre-emergent herbicide will likely be the key in eliminating this weed, but sometimes there are factors out of your control. The most commonly used pre-emergent products for cool season residential or commercial properties include prodiamine (barricade), dithiopyr (dimension), and pendimethalin (pendulum), all of which have the same mode of action.
The issue is that goosegrass can develop some resistance, leading to the non-sensitive plant being the prominent invader. Oxidiazon (Ronstar), which has a different mode of action and is effective on resistant individuals, is not labeled for any residential turf. Dimethenamid-p or Tower is also a different mode of action which can be used on all turfgrasses on golf courses, but only warm season elsewhere.
Post-emergent control in cool season is very effective at certain stages and with a narrow group of herbicides. Mesotrione (Tenacity) and Topramezone (Pylex) can be effective on one to five leaf stages in residential and commercial turf. Speedzone is also labeled for control, but this is specific to the one to four tiller stage. Pylex is also the choice for later, larger plant control. Warm season becomes somewhat more difficult as well. With fewer herbicides available for residential turf, hand removal or directed, spot applications with a non-selective may be your only option.
As always, let us know if there are any questions.