The Pros and Cons of Poa Annua

Poa Prose

According to the Father of Annual Bluegrass, Dr. Joe Vargas, Poa annua has gotten a bad rap.

It is no secret that Poa annua has had a less than spectacular track record. The knocks on Poa have been that it is not heat tolerant, not cold tolerant, and produces too many seed heads. However, many of its positive characteristics seldom get the recognition that is due. Increased shade tolerance, ability to recover after a major stress event, and faster response from fertilizer inputs are rarely mentioned when the topic of Poa annua comes up.

Vargus argues that Poa annua does not die due to heat, Poa dies because of diseases. He cited examples of healthy poa stands during the middle of the summer in Atlanta, Georgia. Locally, Poa is routinely found in greens that have summer temperatures well into triple digits, i.e. Redding, Sacramento, Stockton, Visalia, etc. When conditions exist for disease development and preventative fungicides have been applied, Poa annua can survive adverse environmental conditions.

It is well documented that Poa annua has more tillers per inch than the other commonly used plant material for putting surfaces. Researchers have also reported that the photosynthetic rates of Poa annua have been 40 % higher when compared to the “industry standards” for putting greens.

Dr. Vargas pointed out several cultural practices that favor annual bluegrass. Deep vertical mowing once the spring flush of growth has started. The juvenile tissue that is formed handles the upcoming summer stresses better than older, mature tissue. Aerification should also occur during the initial green up period and during the peak production of seed heads.

A new cultivar of annual bluegrass is now available. Peterson’s creeping annual bluegrass was released from the extensive work of Dr. Don White from the University of Minnesota. Some of the published attributes are a stoloniferous growth habit, very dense and erect growth habit, and tolerates low mowing heights. Several courses have some nurseries of the new variety, but I’m not currently aware of any courses that have it exclusively as a putting surface.

Poa annua is one of the most sensitive turfgrass species in relation to soil salinity. Golf courses that use effluent water and have Poa annua greens are in for a challenge. Weekly monitoring during the dry season for salts is an essential part of any management plan. Leaching with potable water or applying extra amounts of effluent will aid in pushing the salts through the root zone. Core aerification and deep-tine aerification helps when leaching salts from pushup greens.

One of Dr. Vargas’s best lines in defense of the second class turf species is: “Remember, the next time your lousy annual bluegrass turf dies, ask yourself what happened to the wonderful creeping bentgrass it was originally established to”.