Thursday, June 20, 2013

Creeping bentgrass... confirmed?

So I did some sleuthing and to the best of my grass identification skills (which admittedly are extremely poor), I believe I have successfully identified the front lawn turf invader to be creeping bentgrass. It has really grown quite a bit since a year ago and continues to spread. Something must be done. But before I get to that, here's how I went about identifying it.

I went off of my initial guess made last year as a starting point and searched for how to identify creeping bentgrass. This led me to this very useful and informative site from North Carolina State University's TurfFiles which has a profile page for creeping bentgrass describing it's various plant characteristics, including photos.

This led me out into the lawn with my macro lens to see if I could gets some photos of these key plant parts to help identify it and hopefully confirm or deny the identity by comparing with this site.
I was only able to get photos of some of parts as I didn't have much time. However, after inspecting the plant a bit and the photos compared with the TurfFiles photos it already looked like a match to me, but I'll get to that in a sec.

I also remembered a handy tool for identifying grass that I had tinkered with from Purdue University in the past. This tool helps to narrow down an identification based on some of the plant characteristics: vernation, ligule, auricles, leaf tip, leaf surface, mid-rib, collar, growth, and seedhead. I'm certainly still learning about these little plant details (never would have guessed that there'd be so many parts to grass), but I found the tufgrass identification guide linked from the tool to be a good introduction. Using this tool, I entered the characteristics that I was the most certain about (and by certain, I mean not at all certain):
  1. Membranous ligule
  2. Absent Auricles
  3. Pointed leaf tip
At this point the tool had already filtered the possible contenders with a 100% match to just two: creeping bentgrass and colonial bentgrass. Additionally, I entered the leaf surface as ridged, but this didn't change anything as they both have that as well (and it turns out all but growth habit are the same between the two). Here are my photos that show these things:

A bit of a plant that I pulled

Shows the logn membranous ligule (the white
part) and the lack of auricles

After pulling back the blade
Rotated and even closer.

The blade tip pointed (the boat-shaped tip of a blade of kentucky bluegrass can
also be seen to the right)
So, the next step is to discern between colonial and creeping bentgrass. The nice thing about the tool is that you can view photographs of each of the parts for each specific type of grass, in addition to more specific information about it. It further states that colonial bentgrass has a short membranous ligule, while creeping bentgrass has a long ligule, with photos showing each. So even without knowing anything else other than these 3 or 4 attributes, the long ligule distinguishes the two.

But there's more. For colonial bentgrass it states:
"Technically possesses rhizomes and stolons they are generally absent and this species assumes a bunch-type growth habit."
 And creeping bentgrass:
"Bluish-green color, very fine leaf texture, tall membranous ligule, tolerates close 1/2 inch. Leaves may appear slightly rough along the edges, strongly stoloniferous."
So furthermore the two can be distinguished by their growth habits. One of the first things I noticed about the grass when I saw it was how it appeared to grow "horizontally" (likely via stolons, but I've yet to confirm this). It doesn't sound like colonial bentgrass would grow like this.

So there you have it: a positive identification... ?

Assuming so (and I feel confidently enough), the next step is to take action; and Tenacity herbicide sounds like the best available option. More to come.

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