Cold Temperature Damage and Spring Green-Up of Warm-Season Grasses
Green-up of some warm-season grasses started in February and then March hit hard. Early April was also below normal temperatures. We had indication by late April that warm-season grasses had been hit pretty hard from either low winter temperatures, extended periods of low temperatures, and/or early green-up in February followed by low temperatures.
Because of the conditions experienced this winter and spring, it seems that no warm-season turfgrass species totally escaped damage. We also have seen damage from the coast to the mountains—wherever warm-season grasses are grown. Turfgrasses that were installed in 2017 (especially late in the year) were more likely to be devastated due to maturity, but many of the damaged areas had mature turfgrass.
The most devastation I have seen has been with St. Augustinegrass in the Piedmont parts of the state. I have seen 100% winterkill of this grass in some areas. Centipedegrass in the Piedmont has also had widespread damage in some areas but seems to be greening up ok in some locations. Disease hit some centipedegrass during the green up periods that further set back some grass stands.
Bermudagrass is normally quite tolerant to most of our winters, but I have seen some moderately damaged bermudagrass and in a few cases some heavily damaged bermudagrass stands. The worst damage on bermudagrass seems to be those grasses that greened up early (February) and then were more susceptible to low temperatures in March. This resulted in some cultivars that are normally very cold temperature tolerant getting hit harder than those cultivars generally considered less cold tolerant.
This year’s zoysiagrass damage seems to have a strong relationship with its growing conditions and health status going into winter. Lawns areas that tend to stay wet and/or grasses that went into fall a bit weaker (traffic- or shade-stressed, poorly rooted), tended to have more winter damage. I have also seen some pretty heavy large patch areas on some zoysiagrasses this spring. So, like centipedegrass other factors than just winter temperatures may come into play.
The end result for the warm-season grasses will be delayed greening and very slow fill in the “dead areas”. In some cases, re-establishment may be necessary. Warm-season grasses have the ability to fill by rhizome and/or stolon growth but if the damaged area is extensive that could take weeks to months before full density is achieved. Until there is adequate fill of turf, weeds will have a greater opportunity to come into the stand. Post-emergence herbicide applications may be necessary to keep weeds in check. Turf managers should also monitor for disease and insect pressure during the early spring through the recovery period.