Warm-season turfgrasses such as Bermuda, centipede and zoysia often suffer some common problems with springtime green-up. Here are a few of the more common management issues.
Mowing height is the most common problem as these grasses go from dormancy to active growth. Scalping is more common in zoysiagrasses, especially in the denser-growth cultivars like Emerald.
Zoysia grasses don't tolerate scalping as well as Bermuda. As a rule, zoysia will be set back anytime it's cut low enough that you can see the black mold under the leaf canopy. This is generally below the node of the growing leaves. It can occur at any mowing height from as low as half an inch to more than 2 inches.
Regardless of the grass species and normal mowing height, taking the grass down below the node will set it back. Generally, the higher the mowing height, the more this is a problem. Ideally, maintain Bermuda, zoysia and centipede between 1 and 2 inches.
Mowing frequency is just as important as mowing height. If you remove more than one-third of the leaf height at a single mowing, the grass will be stressed.
Fertility requirements differ with each grass. No matter what the species, though, fertilizing too early in the season - before soils are warm enough to support continual growth - can accelerate green-up but cause detrimental long-term effects.
Fertilizer and maintenance
Fertilizing these grasses in late-winter or early spring can cause them to break dormancy. Then when the inevitable late-season cold snap hits, they've used their stored food reserves. They have no energy to withstand environmental extremes. To avoid this, don't fertilize until the soil reaches 65 degrees.
Thatch, as lawns get older, becomes more problematic, particularly if the turf has been mowed above its recommended height ranges. Increased thatch slows down the turf's spring transition. It makes it more susceptible to disease, too.
Water too much or too little or even a combination of the two can cause problems for grasses, especially zoysia.
Diseases can strike during spring green-up. The most common is Rhizoctonia large patch, which appears as large areas of blighted grass. This disease is most active when night temperatures are between 50 and 60 degrees. When conditions are right, it's common for the disease to become active first in the fall and then again in the spring.
You can see its typical "halo" when the disease is active. Fall and spring fungicide applications can control it. For a fungicide recommendation, contact the Hall County Extension office.
Billy Skaggs is an agricultural agent and Hall County Extension Coordinator. Phone: 770-531-6988. Fax: 770-531-3994.