Friday, March 30, 2012

Putting Down Roots

In case you're not signed up for Golfdom's e-newsletters, Karl Danneberger, Ph.D., our science editor, penned the below piece on Poa annua facts.

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Some Interesting Facts about Poa annua

Depending on the climatic region Poa annua is a plant that you either try to manage as a desirable turf, or it is a weed to be removed. Its evasive characteristics are due in a large part from the evolution of different survival strategies (Cline et al., 1993). One strategy is its broad genetic base resulting in a wide range of genotypes within a small area like a golf green. Poa annua has also maintained its ability to flower and produce seed under low mowing heights. 

Below I have provided some facts about Poa annua from a paper by Dr. Mary Lush that I hope you find interesting.

• Poa annua (annual bluegrass) uses 4 to 35% of its top growth (dry weight) for seed production. As a reference, annual plants like cereals invest 20 to 50% of their top growth for seed production.
• Annual seed production on a golf green is between 150,000 to 650,000 seeds per meter squared per year (177,000 to 767,000 seeds / square yard / year). The majority of this seed would be produced from spring through early summer.
• Approximately 75,000 to 225,000 tillers per meter squared per year flower (88,000 to 265,000 /square yard /year)
• During the growing season annual bluegrass tiller mortality is roughly 100,000 tillers per meter squared per month (118,000 tillers / square yard / month). Annual bluegrass has a strong potential for replacing dying tillers with new ones. Obviously sustaining favorable growth through the season is critical in maintaining annual bluegrass turf.
• Annual bluegrass seed dispersal is passive. The mechanism of dispersal is by human (animal) or equipment. Annual bluegrass has been found where human disturbance has occurred, which means it is found on all 7 continents.

Editor's note: "Puttin' Down Roots," an e-newsletter from Golfdom and sponsored by BASF, focuses on plant health. Each month, Golfdom provides readers with a useful plant health tip so they can do their jobs easier.

Karl Danneberger, Ph.D., Golfdom's science editor and a turfgrass professor from The Ohio State University, can be reached at

Cline, V.W., D.B. White, H. Kaerwer.  1993.  Ovservations of population dynamics on selected annual bluegrass-creeping bentgrass golf-greens in MN. International Turfgrass Society Research Journal 7:839-844.

Lush, W.M. 1988.  Biology of Poa annua in a termperate zone golf putting green. I. The above-ground population. Journal of Applied Ecology 25:977-988.