first_imgBy Clint Waltzand GilLandryUniversity of GeorgiaWarm-season turf grasses such as Bermuda, centipede, zoysia andSt. Augustine suffer some common problems with springtimegreen-up. Here are the ones we see most often.Mowing height is the most commonproblem as these grasses go from dormancy to active growth.Scalping is more common in zoysia grasses, especially in thedenser-growth cultivars like Emerald.Zoysia grasses don’t tolerate scalping as Bermuda will. As arule, zoysia will be set back anytime it’s cut low enough thatyou can see the black mold under the leaf canopy. This isgenerally below the node of the growing leaves. It can occur atany mowing height from as low as 0.5 inches to more than 3 inches.Regardless of the grass species and normal mowing height, takingthe grass down below the node will set it back. Generally, thehigher the mowing height, the more this is a problem.Ideally, maintain Bermuda grass and centipede between 1 and 2inches, zoysia from 0.5 to 2 inches and St. Augustine from 2 to 3inches.Mowing frequency is just as important as mowing height. If youremove more than one-third of the leaf height at a single mowing,the grass will be stressed.Fertility requirements differ witheach grass. Consult your county University of Georgia ExtensionService agent or visit www.GeorgiaTurf.com for fertilityrecommendations.No matter what the species, though, fertilizing too early in theseason, before soils are warm enough to support continual growth,can accelerate green-up but cause detrimental long-term effects.Fertilizing these grasses in late-winter or early spring cancause them to break dormancy. Then when the inevitablelate-season cold snap hits, they’ve used their stored foodreserves. They have no energy to withstand environmentalextremes. To avoid this, don’t fertilize until the soil reaches65 degrees.Thatch, as lawns get older,becomes more problematic, particularly if the turf has been mowedabove its recommended height ranges. Increased thatch slows downthe turf’s spring transition. It makes it more susceptible todisease, too.Water — either too much or toolittle or even a combination of the two — can cause problemsfor grasses, especially zoysia.Diseases can strike during springgreen-up. The most common is Rhizoctonia large patch, whichappears as large areas of blighted grass.This disease is most active when night temperatures are between50 and 60 degrees. When conditions are right, it’s common for thedisease to become active first in the fall and then again in thespring.You can see its typical “halo” when the disease is active. Falland spring fungicide applications can control it. Consult yourcounty UGA Extension agent for proper fungicides and rates.Applying nitrogen just before or during active infection willincrease disease problems.Cool temperatures make centipedeand zoysia slower to green up in the spring.Microclimates can cause problems,too. Emerald zoysia growing north of Atlanta has been killed bythe low temperatures in shaded sites that don’t get much wintersun.Varietal differences can betroublesome. Some incidences suggest that many types of Emeraldzoysia exist in the landscape and green up at different rates.Cooperative research with the Georgia Crop ImprovementAssociation and Auburn University is under way to evaluate thesegrass differences.(Clint Waltz is an Extension Service turf scientist and GilLandry the director of the Georgia Center for Urban Agriculturewith the University of Georgia College of Agricultural andEnvironmental Sciences.) Volume XXIXNumber 1Page 29last_img read more