ENH 149 Promoting Turf Recovery Following a Hurricane1 L.E. Trenholm and J. Bryan Unruh2 1. This document is Fact Sheet ENH 149, a series of Environmental Horticulture Department, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. Publication date: February 2000. 2. L.E. Trenholm, assistant professor, turfgrass science is in Department of Environmental Horticulture, Gainesville; J. Bryan Unruh, assistant professor, turfgrass specialist is in Department of Environment Horticulture, West Florida REC-Jay, Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. The Institute of Food and Agricultural Sciences is an equal opportunity/affirmative action employer authorized to provide research, educational information and other services only to individuals and institutions that function without regard to race, color, sex, age, handicap, or national origin. For information on obtaining other extension publications, contact your county Cooperative Extension Service office. Florida Cooperative Extension Service/Institute of Food and Agricultural Sciences/University of Florida/Christine Taylor Waddill, Dean. Devastation from hurricanes can cause multiple problems for turfgrass managers, sod producers, and homeowners. Damage may include visible factors such as prolonged periods of standing water, uprooted trees, shading and obstruction from demolished structures, deposition of silt or mud, and damage to irrigation systems. Less visible problems may include damage to root systems resulting from compacted soil and reduced drainage and injury resulting from effects of salt water intrusion. Suggested guidelines for correcting these problems include: 1. Of primary importance to golf courses are greens, tees, and fairways. Of lesser importance is damage to roughs, driving ranges, and out-of-play areas. Uprooted trees should immediately be removed from greens and tees. Indentations in putting surfaces from trees or buildings can be corrected by weekly light topdressing (0.5 to 1.0 cu. yd.) with sand on a weekly basis for 2 to 3 months. Incorporate topdressing by dragging in. For deeper indentations, sod may need to be replaced. Be sure to properly grade the surface prior to laying new sod. 2. Tidal surges or flooding may leave debris or layers of mud or silt on the putting greens. These should immediately be removed to allow sunlight to reach the turf. Any larger debris should be removed by hand and any mud layers should be removed with a flat-headed shovel. The area should then be washed with a stream of fresh water to move material from the surface of the green. Heavier irrigation should then be used to flush any remaining material from the leaf surfaces. Since much of this material is fine-textured, care should be taken to remove all material from the surface and avoid washing it into the soil. This will aid in minimizing potential drainage problem in the future. 3. Test salinity levels of all irrigation sources. Pump out any contaminated irrigation lakes and refill with fresh water. 4. Elevated salinity levels may damage turf. Soil should be thoroughly flushed with fresh irrigation water to move the salts through the soil profile. Irrigation water may require blending of fresh sources with saline sources to produce an acceptable irrigation water. Salinity levels may also be managed by improving drainage. Verticutting and aerification programs should be utilized.
Promoting Turf Recovery Following a Hurricane 2 5. Soil should also be tested for salinity level. Electrical conductivity (EC) of soils is generally 2 to 10 times greater than that of the irrigation water applied to them. EC readings between 4 and 12 dS/m are moderate, while anything higher than 12 dS/m has excessive levels of salt. If only saline water is available, irrigate at rates exceeding evapotranspiration (ET) to leach excess salts through the soil. If the soil is allowed to dry out, salt deposits may from on leaf or soil surfaces, which will dehydrate the turf. This excess watering should be approximately double that normally used to meet ET demands. 6. Gypsum (calcium sulfate) may be used to remove the sodium off the soil exchange and replace it with calcium. Due to its low water solubility, gypsum works best when incorporated directly into the soil. Core aerification preceeding gypsum application provides for effective incorporation of gypsum into the soil profile. Once the gypsum reaches and reacts with the salinity in the soil, a minimum of one foot of water is required to leach the salts through the soil. More water will be required on soils with higher sodium levels. To determine effectiveness of gypsum application, the following may be done: a) Take a one quart soil sample from the soil surface. Thoroughly dry and pulverize the sample until the largest particles are approximately the size of coffee grounds. Add a heaping teaspoon of powdered gypsum to one pint of the soil and mix thoroughly. Leave an equal amount of the soil sample untreated, b) Prepare two cans, each 3 to 4 inches in diameter and 4 to 6 inches in height. Cover one open end of the can with wire screen to allow water, but not soil, to percolate through. Put treated soil in one can and untreated soil in the other. Fill each can approximately 3/4 full with soil and pack by dropping can from a height of 1 to 2 inches onto a hard surface several times, c) Fill the cans with the irrigation water in question, being careful not to disturb the soil. Collect at least 1/2 pint of the water as it drains through the treated sample, and compare this with the amount obtained in the same time from the untreated sample, and d) If less than half as much water has passed through the untreated sample as has passed through the treated sample, your soil contains excess exchangeable sodium. In this case, the addition of gypsum will improve permeability and soil condition. 7. Increments of approximately 50 pounds of No. 8 sieve gypsum should be applied per 1000 sq. ft. until the EC is reduced. Irrigate with at least one inch of water following each application. 8. Seashore paspalum has the best salt tolerance of any warm-season turfgrass. If you are using this species, several of these salinity reduction programs may not be needed. If dealing with bermudagrass, St. Augustinegrass, or zoysiagrass (medium salinity tolerance), these practices would be recommended following salt water intrusion. 9. Areas of compacted soil should be aerified and topdressed to improve drainage and air circulation to the roots. Avoid use of heavy equipment or any other type of traffic on these areas until turf has begun to regrow.