Cover Story
COMING SOON
Poa annua Seed for Greens and Fairways By David R. Huff, Dept of Plant Science, Pennsylvania State University
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FIG. 1. A majority of America’s top golf courses maintain local land races of Poa annua as their putting surface because of its superior quality characteristics of high shoot density, upright growth habit, and persistence under close mowing heights that yield the fast putting speeds demanded by these top courses. Thus, there’s a need for commercially available seed of improved, stress tolerant Poa annua varieties that would benefit golf course superintendents and architects in their own establishment and renovation projects. 12 Pennsylvania Turfgrass • Summer 2022
or the past 27 years, I’ve been working to develop a commercial seed supply of dwarf perennial Poa annua varieties that are tolerant of biotic and abiotic stress for use on golf course putting greens and fairways and I’m proud to announce that the completion of this goal will soon be achieved. This article is an overview of that long 27-year journey and to begin, I need to address one of the very first questions posed to me when I started the Penn State Poa annua breeding project back in 1994 as a brand-new assistant professor. ‘Why would you breed Poa annua, isn’t that the weed we’re all trying to kill?’ was the question. And it’s a great question. That’s because Poa annua is considered a noxious weed in many states and for many decades there’s been research and chemical product development single-mindedly devoted to eradicating Poa annua from planet earth. However, Poa annua is a marvel of evolution and is doggedly reluctant to go extinct. According to Heap (2021; www.weedscience.org), Poa annua has developed herbicide resistance to nine modes of action involving 23 different active chemistries. And so, the battle continues. For example, in 2018, the USDA awarded a $5.6 million grant (http://resistpoa.org) for studying Poa annua’s many herbicide resistance mechanisms and to determine if any cultural practices may lessen the economic impact of Poa annua invasion. So why would anyone spend their entire professional career trying to breed improved varieties of such a beast? Well, there’s another side to the Poa annua story, which is that it plays an important role in the history and legacy of the game of golf in America and around the world. According to a 2015 land use survey conducted by the USGA & GCSAA (see references), there is more acreage of Poa annua on US golf courses (146,839 ac) than either perennial ryegrass (138,781 ac) or creeping bentgrass (127,608 ac). And, of the nine turfgrass species surveyed, Poa annua ranked third in popularity, behind only bermudagrass and Kentucky bluegrass, and is the only one of these turfgrass species that doesn’t exist as commercially available varieties. Thus, all of this Poa annua acreage exists simply as a collection of localized natural ecotypes (also known as “land races”). On putting greens, the acreage of Poa annua (10,877 ac) is nearly half that (43%) of creeping bentgrass (25,327 ac) and a bit more than bermudagrass (10,055 ac). However, over the 10-year period between 2005-2015, the putting green acreage of Poa annua actually increased (+3.4%) whereas that of creeping bentgrass decreased (-9.6%), and so the relative acreage of Poa annua compared to bentgrass is increasing despite there being no commercial seed supply. Another salient point to make regarding the use and value of Poa annua putting
