#!@&* Poa annua

Poa annua (annual bluegrass) is commonly reffered to as the most prolific "weed" of golf course turf.  It may be a weed to most, but some superintendents must live with the reality of coddling this grass through stressfull summers and hoping it survives stressfull winters.  At Widow's Walk we experience both ends of the Poa spectrum; trying to keep it alive as our primary fairway turf, while keeping it off of the putting surfaces.

The fairways were grown-in as a blend of Colonial Bentgrass and Creeping Red Fescue, but upon my arrival in fall of 2001 very little of the original grasses remained.  Reasons for the infestation of Poa are not certain, but in my experience I could guess that the original stand of turf had a hard time standing up to the incessant cart traffic coupled with the very poor soil beneath the fairways.  These factors would have lead to a classic "weed infestation", where a weed will take over an area where the indigenous species has been weakened.  If the Colonial/Red Fescue stand was injured from cart traffic or mis-managed in any way, the seeds of Poa annua were allowed to germinate, and eventually become the dominant grass.  I assure you that this can happen fast, but conversion the other way can be very slow and tedious (more on that in later posts).  So a weed is no longer a weed when it must be managed as the dominant grass, which I have had to do with the fairways at Widow's Walk.

Spring is such an important time for the management of Poa annua.  I will discuss the various strategies used to keep Poa alive in future posts, but will now concentrate on seed-head control.  One of Poa's most annoying traits is its ability to produce an immense amount of seed at ANY cutting height.  Think about your lawn for a minute.  If you skip a mowing or two in the late spring you may see the emergence of seed-heads that will grow above the leaf blades by a few inches.  When you finally get out there to mow, the seedhead is mowed off, and as long as you keep up with the mowing they will not be seeen again.  Poa annua will produce seed-heads at 2.0" (rough), 0.5" (fairway) and 0.125" (putting green).  There is an opportunity to stop this from happening by timely application of a growth regulator.  On the fairways at Widow's Walk we use Embark T&O growth regulator applied in mid-April.  As seen by the photo below, this stuff really works when used properly.

The light colored section was covered up by a piece of plywood while we applied the Embark, thus making a "control".  What you are seeing is actually thousands of seeds that were produced in this 2'X3' square.  If Embark was not applied our fairways would more or less have this appearance for at least two weeks.  The reason for controlling seed-heads is three fold.  First, seed structures are UGLY because golfers are expecting lush green fairways not white straggly fairways.  Second, in order to keep the greens free of Poa annua it is best to have as little seed on the bottom of a golfer's spikes as possible, as they can become an instant seed planter.  Finally, if the plant is "told" not to produce seed structures, the carbohydrates will instead be used to produce roots and tillers, making the plant stronger for the summer months ahead.

Is Poa annua a weed?....the answer is sometimes.  The definition of a weed is "a plant out of place", so at Widow's Walk Poa annua lives as a weed on the greens and as a desired species on the fairways.  This dichotomy is just one challenge that we face at Widow's Walk as we try to produce the best playing conditions within our means.