Category: Grassy Weeds

POAA Gone WILD

Annual Bluegrass (poa annua) is a winter annual grassy weed found from Florida to New England and west to California. It is considered a weed in Charlotte’s Fescue and Bermuda lawns, but is actually planted on some lawns and golf courses in other parts of the country.. In our area PoaA germinates in early November, matures over the winter, sets seed and dies in the spring. Right now the weed is very noticeable with it’s white seed heads and bunch type growth. This weed grows everywhere in shade and sun. You’ll see it on roadsides, open fields, golf courses and residential lawns. Once we hit the 80 degree mark on a consistent basis, the PoaA plants will begin to turn brown and die.

The PoaA has gone absolutely crazy this spring. Weather conditions have been perfect for this weed invasion. We just went through the wettest fall and winter on record. This Spring has also seen above average precipitation. The Winter was relatively mild and recent cool nights have kept the PoaA growing and seeding rapidly. There is no viable way to spray out PoaA in Fescue lawns. Several Ag Companies have new products claiming control in Fescue. We have field tested all of the newer products and saw less than acceptable results. These products are very expensive and have to be applied 3 times within 30 days at costs exceeding $200 per acre. We can not justify asking our customers to spend several hundred dollars on a treatment program for PoaA with no guarantee for control.

The vast majority of the PoaA seed comes from the soil itself. Seeds can lay dormant in the soil for years and are brought to the surface through aeration and heavy rainfall. Birds, insects, wind and rain run-off can spread seeds from lawn to lawn. Unless you use blue tag certified, 0% weed content grass seed in the fall you run the risk of spreading the problem.

Right now the best thing you can do to mitigate the issue in Fescue lawns is to mow it at the highest setting (3 3/4-4 inches.). Cutting the grass short will increase PoaA seed production and force the plant to thicken. There are a couple of viable options to alleviate the PoaA problem next spring. Early aeration/seeding (Aug-Sep) and late fall pre-emergent is one option. Foregoing aeration and just seeding the lawn is another option that worked for me.

Weed Control In The Fall

When battling weeds, you must know thy enemy. Weeds are generally defined as any unwanted plant growing in the lawn or landscape. Weeds are categorized first as broadleaf or grassy. Next one must determine if it’s an annual or perennial. The next step in classification is to whether the weed is a summer or winter cycle. The weed elimination plan depends on what we are dealing with.

Perennial Grassy Weeds- these are the most difficult type of weeds to get a handle on. Dallisgrass, orchardgrass , poa trivialis, nutsedge, and bahaia are the ones we face here in the Piedmont area of North and South Carolina.

Annual Weeds- These weeds are relatively easy to control before they germinate with a pre-emergent program. Crabgrass, lespedeza, spurge, poa annua and henbit are quite common in Fescue and Bermuda turf

The biggest issues many face right now are the annual grassy (crabgrass) and annual broadleaf weeds (spurge/lespedeza). These weeds germinate in the spring, mature over the summer, sets seed and dies in the fall. Lawns that did not receive pre-emergent treatments in the spring, are right now loaded with annual weeds. I saw the first annual weed germination in late March this year. So unless that first pre-emergent was applied before that date, expect to see issues now. In this case an ounce of prevention is worth a pound of cure.

Once we hit Mid September, all of the plants energy is geared towards seed production because of its annual nature. The weeds will not absorb any herbicide. They can not be effectively controlled. These weeds are basically dying on their own at this time of year. The cooler it gets at night, the quicker they die. There is absolutely no sense in even trying to use herbicide now.

For Fescue lawns requiring seeding this fall all you need to do is “scalp” the lawn down with the mower on the lowest setting. This will effectively stop any re-growth and allow for good seeding results.