The first day of fall on September 22 ushers in cooler weather, or at least the promise of it, and also signals shifts in cultural practices for turfgrass professionals. Fall is a crucial transition time for both warm and cool season grasses, and expert care given now will benefit grasses not only for the fall but well into next spring and summer.
“One of the least expensive things professionals can do that has the biggest impact on turfgrass is to collect soil samples for testing,” said Jutt Howard, NG Turf VP of Business Operations. As an example, Howard points out the common mistake of waiting too long to apply lime on warm season lawns. “It takes several months for lime to lower acidity levels, so soil test and apply any recommended lime now in order to give turfgrass a stronger start in the spring.”
Merett Alexander,NG Turf’s VP of Golf Course Sales agreed, emphasizing the importance of soil testing for proper fertility. “You can fertilize, but it will be wasted if the pH is out of balance because the grass won’t be able to absorb the nutrients properly.”
Established lawns with balanced pH require soil testing every two years, but experts recommend soil testing for new lawns or acidic soils once per year until the proper pH balance is sustained. In addition, testing every year is an easy way to tailor fertility for optimum benefit and plant vigor—exactly what every turfgrass pro works to achieve.
Warm season grasses transition from growing season to dormancy during fall, indicating a change in fertility application. “Although you want to pull back on nitrogen going into the fall, now is a great time to apply phosphorus,” Howard explains.
Nitrogen encourages top growth, interfering with the transition to dormancy when warm season grasses typically shift from top growth to energy storage in the roots, rhizomes and stalons. Phosphorus promotes root growth, however, helping turfgrass prepare to survive winter months.
On the other hand, cool season turfgrasses, like tall fescue, are just gearing up for their peak growing season, so fall is prime time for nitrogen-rich fertility application. Again, soil testing will give you the exact formula for amending the soil to achieve optimum growth and overall turfgrass health.
Fall is also time to get the jump on winter weeds. A fall and a spring application of pre-emergent herbicide will significantly reduce weed propagation throughout the year. Because these herbicides don’t work on seeds or on plants that have already emerged, timing is important. Too early and the seeds won’t have germinated. Too late and the plants will already be up.
To control prevalent weeds like annual bluegrass, henbit and common chickweed, the Unviersity of Georgia (UGA) Extension Service recommends applying pre-emergent herbicide when temperatures fall between 65° and 70°F at night.
For spring weeds like crabgrass and goosegrass, re-apply in February or March before soil temperatures reach 55°F.
As their name suggests, fall armyworms usually appear in early fall, but they may show up as early as July or August, feeding on all turf varieties.
Armyworms harm grasses by chewing the plant tissue and creating ugly web patterns in the leaves. The armyworm larvae strip foliage in one area of a lawn and move as a group, to the next source of food, leaving significant damage in their wake. Application of Bt insecticides, which are nontoxic to humans, offers the best control to eradicate the caterpillars without harming beneficial insects.
Fire ants may pose no real threat to turfgrass lawns, other than their unsightly dirt mounds, but they do pose a threat to humans and animals. Because fire ant colonies thrive in extensive underground tunnels with up to half a million ants and multiple queens per acre, wiping them out entirely is nearly impossible.
The most effective method for control is to apply broadcast bait each fall and spring. Spread bait in a four-foot radius on and around the mounds, being careful not to disturb the ants in the process. For persistent mounds, follow up with liquid insecticide poured down into the center of the mound. Once activity ceases, the mounds can be safely knocked down.