The plants pictured above are the same genus and species - Poa annua. One, I pried out of some gravel -- the other, I cut out of our seventh green. The physical differences between them are due to their 'biotype' and culture (i.e. mowing height, topdressing, fertilizer, aerifying) and is what makes Poa annua a versatile grass and strong competitor. But, it's not a grass you can buy. This is a wild species native to Europe, distributed worldwide, and is normally considered a weed.
Why I bring this to your attention is that most every 'Poa' plant shares one terrible trait -- they're prolific seed producers in May. It's this production that's caused such great courses, like Oak Hill in Rochester, to choose the sterilize/kill all of their greens in the early 90's in attempt to improve the surface. They wanted it gone because it was considered a 'weed' and a weak grass, but I would argue it's neither.
In May, Poa physically changes. It swells up and gets 'puffy' as it pushes out seed. It gives a terrible ball-roll only a few hours after it's mowed and becomes even bumpier and slower the later it gets in the day. Think of how hard it is to roll out of a water bed compared to a futon and you get a good picture of how a ball reacts as it rolls across a 90% Poa green in May. The only defense against this physical change, and it's a great one, is topdressing every week.
Seed production is it's primary mode establishment and the reason courses like Oak Hill try to eradicate it in favor of planting bentgrass, a species that propagates itself more vegetatively. Courses that enjoy bentgrass don't suffer the issues Poa has in May as the bents don't go to seed. They grow in an orderly fashion and putt almost no differently than they do in July.
Within 10 years, much of the Poa had returned to Oak Hill and they're back to where they started -- namely, trying to control seedhead production with chemicals like the rest of us. The only true way to eradicate Poa annua is to strip the area, fumigate, reseed, and begin a never-ending regime of specialty herbicides that don't let the plant get a foothold. Even then, your chances are only 60/40 you'll keep it at bay. It's like rust -- it never sleeps.
To be sure, replacing Poa with creeping bentgrass lends a great ball roll in May and more consistent appearance through the year. For this reason, hundreds of courses still spend big dollars on conversion attempts.
Unfortunately we had a rainy and cool spring which made timing the application for seedhead control tricky this year. At Tuscarora, we normally apply on fairways and greens for seedhead control in attempts to remediate the speed reduction and fairway cutting quality. Although we were partly successful on greens in between rain events, we were only able to apply on 4/18 fairways. To date, cutting fairways and rough is like cutting bailing wire. It literally stops mower reels from spinning if let to grow more than two days. We're having to re-sharpen blades weekly which is normally a monthly routine.
As the weather heats up, Poa goes into summer survival mode which is largely one of conservation -- this is when it shines and why Tuscarora has great greens. We are over 95% Poa annua on greens here. At that percentage, bentgrass is now the weed.
Poa boasts higher shoot density than the most expensive bentgrasses, it can be mowed shorter than many bentgrasses, it's ultimately smoother and faster than bentgrasses, it doesn't produce as much thatch as bentgrass, and it's pesticide and water requirements are similar if not edging out bentgrass.
So, take heart in May on 'pokey' Poa greens. It's a normal condition of a very hardy species of grass that makes up 70% of our course.
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