It is easy to recognize Poa annua growing in bermudagrass this time of year. Green clumps of grass growing amidst brown or semi-green fine turf are easy to identify. It is just as easy to identify how well your herbicide program worked based on the number of clumps on your course.
What is not as easy to identify, and doesn’t get the same consideration as an herbicide program, is weather and golfer traffic. Since last October the weather in the southern part of the region has been ideal for Poa annua germination and growth. Mild weather for most of the winter allowed the winter annual grass to thrive. Another potential cause for an increase in Poa annua is an increase in rounds played. With more rounds comes more traffic, and more potential stress.
The rise in Poa annua is not just in fairways and rough, but also on bentgrass putting greens. I’ve heard more courses mention this than in previous years. As putting greens thin late in summer, this creates voids and an opportunity to gain a foothold. It is easy to be concerned if your course has more Poa annua on greens this spring than you’ve had before, but it doesn’t necessarily mean you need to make any drastic herbicide applications to combat it.
My sense is given how mild the weather was, most of the Poa annua is the annual biotype and should die off with warmer weather. This doesn’t mean that your greens will have massive voids and turf loss, but rather as the weather warms bentgrass will start growing more aggressively and Poa annua will slowly fade away.
In some instances, Poa annua might survive, in which case it can be managed with plant growth regulator applications. In rare cases, preemergence herbicides might be necessary this fall or early winter. Before you throw your entire herbicide program away, think about how weather and play impact Poa annua development.
Northeast Region Agronomists:
Adam Moeller, director, Green Section Education – amoeller@usga.org
Darin Bevard, senior director, Championship Agronomy – dbevard@usga.org
Elliott L. Dowling, senior consulting agronomist – edowling@usga.org
John Daniels, agronomist – jdaniels@usga.org