Drainage Project Follow-Up: Poa annua Effects

After our last post, we received several questions regarding our drainage project and how it might affect our Poa annua. If you've played Adams Pointe recently, you probably haven't noticed many issues with our fairways. But because of the amount of Poa annua on the property and the inevitable summer heat, that will almost certainly change, even with the added drainage.  

No. 3 Fairway showing contrast between bentgrass and Poa annua

The picture above shows two very different shades of green in the No. 3 fairway. The darker green is bentgrass, and the lighter green/yellow on the right side of the fairway is Poa annua. The color difference is partly caused by a plant-growth regulator application to the fairways. This application helps slow vertical growth in the Poa and weaken its competitive ability. The Poa is typically easy to spot, but this spray really illustrates the amount of Poa we have on the property. 

The optimal temperature for Poa root growth and shoot growth is 55 to 65 degrees and 60 to 70 degrees, respectively. Overall, root growth is more important because turfgrass can maintain growth at relatively high temperatures, as long as soil temperatures stay cooler. As you can see with the temperature ranges listed above, we quickly exit optimal Poa temperatures in late May or early June. Once soil temperatures increase beyond that optimal range, it doesn't take long for the Poa to decline. As you continue to visit Adams Pointe throughout the year, you might notice these changes to the Poa. This doesn't mean our drainage project isn’t working, but rather, summer has rolled in temperatures the Poa annua cannot survive. We use the annual Poa loss to our advantage, seeding bentgrass in the affected areas in the fall, hoping it will outgrow the Poa in late fall and early spring. That’s no easy task, as Poa annua is the most widely distributed weed in the world, even documented as an invasive species in Antarctica. Everything from animals to wind scatter its seeds, and during optimal temperatures, it establishes rapidly. We will never completely rid the property of Poa, but with our current management plan, we hope to limit its growth and give the bentgrass every chance to compete.

For further reading about Poa annua control in turfgrass, check out this article from the University of Nebraska-Lincoln: http://turf.unl.edu/NebGuides/PoaannuaControls2010c.pdf.