North Florida Fertilization Strategies that Promote Healthy Turf

Transcription

1 North Florida Fertilization Strategies that Promote Healthy Turf Dr. J. Bryan Unruh Extension Turfgrass Specialist University of Florida/IFAS The axe has fallen... Beginning January 4, ALL commercial fertilizer applicators MUST BE certified by FDACS in order to make ANY TYPE of fertilizer application to: Commercial turf or ornamental areas; Turf or ornamental areas of parks or fields (other than agricultural areas); Turf or ornamental area of any residential property. Prior to issuance of this certification, the applicator MUST PROVIDE proof of having received training in "Green Industry Best Management Practices taught by UF/IFAS. 3 The axe has fallen... GI BMP Training Options You must enclose a certificate of completion of training issued by the University of Florida (IFAS) and/or Department of Environmental Protection (DEP) with this application.

2 BMPs are a Starting Point Employment Classification* 3 Pesticide: Handlers, Sprayers, and Applicators, Vegetation, 3, 3,,3 **Landscaping and Groundskeeping Workers 3,,4,54,5 Grounds Maintenance Workers and All Other 3,3,4, Total, 3,4 4, 4,4 *Estimates are based on Standard Occupational Classification Codes. **Landscape or maintain grounds of property using hand or power tools or equipment. Workers typically perform a variety of tasks, which may include any combination of the following: sod laying, mowing, trimming, planting, watering, fertilizing, digging, raking, sprinkler installation, and installation of mortarless segmental concrete masonry wall units. Exclude "Farmworkers and Laborers, Crop, Nursery, and Greenhouse" (45-). BMPs are a Starting Point Pre 5 Statewide Fertilizer Rule (a.k.a Urban Turf Rule) Limits N to lb per, ft maximum application rate or. lb per, ft for quickrelease N Limits P to /4 lb P O 5 per, ft per application and / lb P O 5 per, ft annually Annual N rates follow UF recommendations Requires lawn care industry to follow Green Industries BMP manual 5 Statewide Fertilizer Rule (a.k.a Urban Turf Rule) Actively Growing means turf that needs mowing at least every two weeks. Nitrogen shall not be applied at an application rate greater than. lbs of readily available nitrogen, per sq. ft. per application at any one time based on the soluble fraction of formulated fertilizer.

3 5 Statewide Fertilizer Rule (a.k.a Urban Turf Rule) Not more than lbs. of total nitrogen per sq. ft. per application may be applied during the spring or early summer; Not more than lb total nitrogen per sq. ft. per application may be applied during the fall or winter. Total NO 3 Leached (kg ha - ) SR Nitrogen Source Study Jay, FL Days 3 4 Percent Growth Potential // 4// // // // // Arrows denote fertilizer application dates. 5 Statewide Fertilizer Rule No major impact in northwest Florida! UF only recommends the. lb rate in those regions of Florida that have summertime fertilizer blackout ordinances. 5 Statewide Fertilizer Rule Keep a watchful eye out for those who may propose a blackout in northwest Florida. UF Recommendation: no fertilizer prior to April 5 and not after mid September. Blackouts: May through September JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC Two week window to fertilize! 5 UF/IFAS Recommendations Table. Fertilization Guidelines for Established Turfgrass Lawns Nitrogen Recommendations (lbs, ft year ), North Florida Bahiagrass. 3. Bermudagrass Centipedegrass.. St. Augustinegrass. 4. Zoysiagrass. 3. Because homeowner preferences for lawn quality and maintenance level will vary; we recommend a range of fertility rates for each grass and location. Additionally, effects within a localized region (i.e., micro environmental influences such as shade, drought, soil conditions, and irrigation) will necessitate that a range of fertility rates be used. These recommendations assume that grass clippings are left on the lawn.

4 GP obst optt sd e GP = growth potential obst = observed temperature (F) optt = optimum turf growth temperature (F) sd = standard deviation of the distribution (sd warm = ; sd cool = ) e = natural logarithm base. ` Percent Growth Potential 4 GP obst optt sd e Pensacola Tallahassee Jacksonville Gainesville Daytona Beach Orlando Tampa Ft. Pierce Naples Ft. Lauderdale Homestead Key West JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC How much nitrogen do the turfgrasses need on a monthly basis? Bahiagrass Bermudagrass Centipedegrass St. Augustinegrass Zosyiagrass Pensacola, FL Mobile, AL Desin, FL Panama City, FL lbs N, ft JAN.... FEB.... MAR APR.... MAY.... JUN JUL AUG SEP OCT NOV DEC Pensacola, FL Mobile, AL Desin, FL Panama City, FL lbs N, ft JAN.... FEB.... MAR..5.. APR..5.. MAY JUN JUL.... AUG..5.. SEP OCT.3... NOV..5.. DEC Pensacola, FL Mobile, AL Desin, FL Panama City, FL lbs N, ft JAN.... FEB....3 MAR.... APR....5 MAY JUN JUL.... AUG.... SEP OCT NOV.... DEC

5 Turf Quality Centipedegrass y=.3+.45x-.x ; R =.* y=5.3+.x-.5x ; R =.*. lb. lb 4 4 Nitrogen Rate (kg N ha - yr - ) Centipedegrass Our results indicate the current UF N recommendation range for centipedegrass in north Florida do not pose an increased risk to NO 3 N leaching. However, they also indicate that the lowest recommended rate of lb N, ft per year may provide more N than is necessary to produce acceptable centipedegrass. A rate of.5 lb N, ft per year would likely produce acceptable quality turfgrass during the entire season and produce little risk to NO 3 N leaching. 5 Growth Rate (g m - d - ) Color Visual Quality A. y=.+.4x-.335x R =.*. lb 3 B. y=.33+.5x-.x R =.* 3.4 C. y=.+.5x-.5x. R =.**....4 Bahiagrass Current N recommendations to bahiagrass in south Florida are higher than is necessary to produce acceptable turf by home lawn standards. The lb N, ft led to acceptable turf quality during each cycle while regression analysis indicated quality could be achieved without addition of N. Turf Quality Ft. Lauderdale y = x -.5x R =.* Citra 3.4 lb 5 y = x -.55x R =.* Jay y = x -.3x R =.* 5 y = 4. +.x -.3x R =.* St. Augustinegrass Results indicate that N applied according to the recommendations for Jay and Ft. Lauderdale produced acceptable quality turf at the low and high N range when turf was not exhibiting stress symptoms during most cycles. However, the minimum N required to produce acceptable turf in Citra was predicted to be 3.4 lb N, ft which represents an increase in.4 lb N, ft per year from the current recommended minimum Nitrogen (kg ha - yr - ) Nitrogen Rate (kg N ha - ) Getting a Response... Research shows that you need.3 lbs /, ft of available nitrogen to see a response in N Source turf % of Applied Nitrogen Released Nitroform Nutralene Polyon SCU IBDU Osmocote

6 Practical Considerations Nutrients must be applied based on the plant s ability to assimilate them. This should supersede any calendar based regimen. Healthy, dense turf is the key to minimizing environmental impact of applied nutrients. As the health of the plant deteriorates one can expect problems. Practical Considerations Timing of application of enhanced efficiency (SR) nutrient sources should coincide with periods of active growth potential. The release period should not extend beyond periods of active growth. Damaged Turf All fertilizer recommendations are based on having a healthy, dense turf that is actively growing. Damaged lawns are commonplace throughout the green industry. Damage can be attributed to a number of reasons Winterkill on Centipedegrass Take all Root Rot on St. Augustinegrass 35 3

7 Winterkill on Centipedegrass Winterkill on St. Augustinegrass 3 3 Herbicide Injury on Zoysiagrass 3 Dinitroaniline Herbicide Injury 4 Dinitroaniline Herbicide Injury + Shade and Over watering 4

8 Nitrogen Leaching in Relation to St. Augustinegrass Turf Density in Northwest Florida 5 SR Nitrogen Source Study Jay, FL Total NO 3 Leached (kg ha - ) Turf Density (-; minimum acceptable) // 3// 5// // // Arrow denotes fertilizer application date. SR Nitrogen Source Study Jay, FL Monthly Total of NO 3 N Leached from St. Augustinegrass and Centipedegrass from Total NO 3 Leached (kg ha - ) // 3// 5// // // Rain (mm) Total monthly nitrate leached kg ha 4 Import on sod Root shed? Winter damage St. Augstinegrass Centipedegrass Actual rainfall Nitrogen application 3 Monthy precipitation (mm) Arrow denotes fertilizer application date. Aug Aug Feb Feb Aug Aug Feb Feb Aug Aug Feb Feb Aug Aug Nitrogen Rate Study Floratam / Empire Empire Zoysiagrass 4 4

9 Correct the Original Problems first! Deteriorated turf? Pest damage what caused the damage? Will it be prevented? Weed infestation what caused this? Winter injury? Old Age? Factors Influencing Recovery Turfgrass Species Growth rate of the grass will dictate recovery. Rhizomatous grasses (with intact rhizome system) will recover more quickly. Stoloniferous grasses somewhat slower. Extent of Existing Groundcover Estimate the remaining level of groundcover. How widespread is the damage? How uniform is the damage? 4 5 St. Augustinegrass Winter Injury Estimated ~5% damage Uniform injury/coverage Extensive Large Patch Injury Estimated ~% damage Uniform injury/coverage Recommendation: Spoon feed every two weeks with..5 lbs N /, ft until covered and then follow standard recommendations. 5 Recommendation: RoundUp and resod! 5 Large Patch Damage Estimated ~5% damage Non uniform injury/coverage Extensive Take all Root Rot Estimated ~3% turf ground cover Non uniform injury/coverage Recommendation: Treat for the disease. Avoid fertilizing damaged site. 53 Recommendation: Resod the damaged area. 54

10 Non Selective Herbicide Applied to Non Dormant Turf Estimated ~5% turf ground cover Non uniform injury/coverage Selective Herbicide Injury Estimated ~% turf ground cover Non uniform injury/coverage Recommendation: Wait for possible recovery. Do NOT fertilizer until turf is completely recovered. 55 Recommendation: Wait for possible recovery. Spoon feed every two weeks with..5 lbs N /, ft until covered and then follow standard recommendations J. Bryan Unruh, Ph.D. West Florida Research and Education Center University of Florida/IFAS jbu@ufl.edu