May 11 , 2007
University of Arkansas, Turfgrass Science Program
Economic Impact of April Frost on Turfgrass Species
Above normal temperatures in March provided an earlier green-up for turfgrasses than normal. However, the frost in early April sent the warm-season turf back into dormancy for a few weeks and caused some damage to cool-season turfs.
Typically in autumn, warm-season grasses such as bermudagrass and zoysiagrass decrease their growth and winter acclimation begins before the risk of any lethal freezing temperatures. As temperatures cool in autumn, photosynthesis is relatively high compared to respiration rates which allow the plant to build a carbohydrate reserve. Warm-season grasses typically have the greatest amount of winter hardiness in early winter and the least amount in early spring as carbohydrate reserves are depleted and plant respiration increases. Therefore, periods in the spring where the temperatures fluctuate from warm to cold rapidly can sometimes be damaging to warm-season grasses, especially centipedegrass which is more susceptible to these temperature fluctuations.
Bermudagrass and zoysiagrass had both greened-up this spring in Late March and growth was to a point in NW Arkansas that lawns were being mown. However, the frosts that occurred during the first week of April sent these grasses back into a temporary dormancy. There were some concerns that this late frost after green-up could cause some winter injury and possibly winterkill. However, it appears that the damage in Arkansas was mainly cosmetic and that little to no winterkill occurred.
Zoysiagrass frost injury symptoms (A and B) can appear very similar to bermudagrass frost injury symptoms. Frost damaged areas also may have symptoms similar to diseases such as dollar spot once the turf begins to green-up and recover (C and D).
Not all states were as fortunate as Arkansas. In Kansas and Indiana it appears that there was 50 to 100% winter injury of some cultivars of bermudagrass. This illustrates the importance of planting cultivars in Arkansas with good winter hardiness. Of the seeded bermudagrass cultivars available, ‘Riviera’ has the best winter hardiness. ‘Midlawn’ and ‘Patriot’ have the best winter hardiness of the vegetatively established bermudagrass cultivars.
Cool-season turfs are better adapted to chilling and freezing than warm-season grasses, but cool-season turfs can still be damaged by spring frosts. Tall fescue seedlings are especially susceptible to damage by frosts. A spring frost after above normal warm weather, such as this year’s, is rare. However, frosts in autumn after Indian summer conditions are not abnormal. Therefore, caution should be given to late fall (October 15 – December 15) seeding dates of tall fescue because injury or winterkill to tall fescue seedlings could occur.
Both tall fescue and Kentucky bluegrass were seeded at the U of A Agricultural Research and Extension center (Fayetteville) during the warm March weather and had germinated before the significant frosts in early April (A). The above images show tall fescue seedlings (B) that were damaged by this year’s frost while the Kentucky bluegrass seedlings (C) in adjacent plots were not damaged. Some of these tall fescue seedlings recovered from the damage, but recovery from damage was slow.
Overall the economic damage in Arkansas from this springs frost was minimal. Hopefully, this will serve as a reminder to use good agronomic practices such as planting bermudagrass and zoysiagrass cultivars with good winter hardiness and seeding cool-season turf during the optimum seeding window (September 1 to September 30).