Poa Seed

If you’ve been out on the course, you may have noticed a ‘whitish’ haze developing on the greens.  What is it?  A disease? A Different type of grass?  I wanted to take a moment to fill you in a bit.

Once again it is that time of year when we see the development of seed heads on the Annual Bluegrass (Poa annua) population within our greens.  Every year in early to mid May, Poa annua produces a flush of seed head that lingers for about 2 or 3 weeks.  It’s a frustrating and challenging time to maintain greens as we see speeds fall off and the greens begin to feel a bit ‘sticky’ or ‘puffy’.

Even if our putting greens were sodded with Creeping Bentgrass, they will gradually transition to a Bent/Poa mix because of the nature of our property. Poa annua is a native grass species and has the ability to establish almost anywhere there is bare ground due to its prolific seed head production.

This isn’t necessarily a bad thing. Poa annua has many positive attributes and, when properly maintained, can provide exceptional putting surfaces.  In fact, many of the top older golf clubs in our region and around Canada and the US have Poa greens, and  many major tournaments such as the US Open are  hosted on courses with Poa greens.

Poa annua does have some problems though; shallow roots which is a significant issue on our greens, disease susceptibility, ability to out compete Creeping Bentgrass and its seed head production among them.  As you can see in the close up photo below, it is quite capable of producing seed heads at extremely low heights of cut. (1/8” or less)

As you play the golf course, you may notice that the seed head is heavier on some greens vs. others. This is in part due to the amount of Poa that is established on each green.  A green like #6  for instance is one of our heavier producers.  I don’t think there is any coincidence that this is most often the green that shows the most disease stress through the summer.  It is widely believed, and I would agree, that greens that do not produce a heavy seed flush will be comprised of stronger rooted Poa plants better able to withstand the stress of summer. Poa Annua the older it gets produces smaller seed heads and can genetically transition into a more perennial type cultivar.

What can we do? Our friends south of the border have access to products (growth regulators) that reduce the extent of seed production.  These products are not available to us in Canada – perhaps they will in time.  In the meantime, we work within our cultural programs (fertility, brushing, verticutting, topdressing) to get through this time period and minimize the effects.

The flush is almost over and things are returning to ‘normal’