Thomas J. Koske | 4/16/2005 2:06:57 AM
Few treatments are required by warm-season grasses that go dormant in winter. The wrong treatments at the wrong time can create a weak and lethal situation, according to LSU AgCenter horticulturist Dr. Tom Koske.
Winter is a bleak month for turfgrasses like St. Augustine, Zoysia, Centipede and Bermuda. Most will be dormant or close to that stage. These grasses grow slower when soil temperatures are below 70 F and very little when they are in mid 60s.
"Fertilizing permanent warm-season grass now makes no sense," Koske says, emphasizing, "It’s not growing!"
The horticulturist elaborates that unused fertilizer can deposit nitrogen and other nutrients into the groundwater. Stimulating winter growth of permanent grass with nitrogen will lead to extra winter kill and brown patch disease.
"If you haven't tested your soil in the past several years, do it now," Koske advises. To test your soil, bring in a pint sample and $7 to your parish LSU AgCenter office. The sample should be a composite of soil plugs taken from several areas 4 inches deep and mixed together.
Lime now if you know you need it or the test indicates lime is needed.
To care for your cool-season grasses such as ryegrass this time of year, Koske says some treatment is needed for best performance. Use 2 to 3 pounds of ammonium nitrate or equivalent nitrogen per 1,000 sq. ft. every four to six weeks to maintain desired growth and color in overseeded rye and other winter grasses. Mow as needed at 2 to 3 inches mowing height. Irrigate as needed to maintain growth, but irrigate your dormant lawn only if it's extremely dry.
Postpone any permanent warm-season turfgrass establishment from seed until late spring, but you may lay sod now if necessary. Establishment is best left until well after spring green-up. Overseed thin or bare areas with rye to check mud and erosion. If you set out freshly cut sod this fall or winter, its lack of roots may require extra attention to watering if dry.
"Be aware that brown patch disease can come and go all winter if weather is mild and grass starts greening," Koske says, advising a treatment of fungicide containing thiophanate, azoxystrobin, propiconaxole, iprodione or PCNB to check its spread. Alternatives include captan, mancozeb, triadimefon, maneb and several others.
"This is important for good spring green-up," the horticulturist stresses, explaining, "If brown patch kills your grass now, it will still be dead in spring."
For information on related topics, look for Gardening and Get It Growing links in the Feature section of the LSU AgCenter Web site: www.lsuagcenter.com. Additional yard and garden topics are available from an extension agent in your parish LSU AgCenter office.