ASK THE HORT AGENT
Question If I can’t get rid of annual bluegrass, can I cultivate it like they do in Kentucky?
Answer There’s nothing wrong with making lemonade from lemons. Europeans cultivate dandelion varieties. Yet dandelions are on our “top ten” weed list. Sometimes a weed for one person is a beautiful or useful plant for another person. Dandelions are a poor substitute for lemons when making lemonade, and annual bluegrass will probably not make a desirable lawn.
Annual bluegrass (Poa annua) is a different species of grass than Kentucky bluegrass (Poa pratensis). Kentucky bluegrass is a perennial and annual bluegrass only lives one year (hence the name “annual”). Both of these grasses do not like heat. Therefore, neither will do well in the South. Our summers are too hot. The comparison between these two is very similar to the comparison between tall fescue and annual ryegrass. Heat is the element that adds the “annual” to both ryegrass and bluegrass.
Annual bluegrass may not live through the summer, but it can be very prolific during the spring. Like many annual weeds, it has environmental conditions which it prefers. It likes moist soil, low mowing height and high fertility (high nitrogen and phosphorus). It also tolerates compact soil very well.
As usual, the first recommendation for pest control is correct maintenance of the desired grass. A healthy stand of turf is your first line of defense against all pests (weeds and diseases). The presence of a weed like annual bluegrass is simply an indication that something is out of whack. Go back to your lawn maintenance calendar and check your timings, rates and heights. If you are doing too little or too much, then problems will pop up.
If soil compaction has developed because of traffic, pets, construction, etc…, then get out the core aerator. Soil compaction may take years to develop and reduce. Be sure to aerate when your grass is actively growing.
Once your cultural practices are back on track, then herbicide usage will be more effective. To break the annual bluegrass cycle, apply a pre-emergent herbicide in the fall. Be sure to rotate herbicide types every 3 or 4 years (triazines, dinitroanilines or ethofumesate). If the environmental conditions and maintenance activities are corrected, then herbicide usage can be reduced or discontinued after a few years.
Since annual bluegrass will not make a viable turfgrass, lemonade is not really an option. Your neighbors would probably like it better if you decided to go with a more European (dandelion) lawn. Not really!
For more annual bluegrass info visit http://hgic.clemson.edu/factsheets/hgic2300.htm If you don’t have internet access, call the Cooperative Extension Office at 893-7533 or email me at firstname.lastname@example.org
Kentucky bluegrass is not native to Kentucky. It was transported from Europe by early American colonists. What would we have called bluegrass music if this grass had not been brought to America? Bill Monroe and Buffalo Grass Boys?
Gary L. Pierce
Horticulture Extension AgentHarnett County