Sports field turf needs sunlight to make its own food.
Warm season turfgrass needs at least twice as much sunlight as cool season turf. Without sufficient sunlight, the turf quickly begins to deteriorate and have shade stress problems. Shaded areas of sports fields are especially prone to this reaction because sunlight in the shade is low in the red wavelengths needed for energy production.
Turf growing in the shade of nearby trees or stadium structures reacts by lengthening, thinning in density, and becoming more succulent. It can’t fend off diseases as quickly as sunny turf, and is injured more easily. Weeds grow. The turf must compete for nutrients from nearby shade trees. The ground may begin to look bare or have drainage problems.
Some sports field owners have responded to this crisis with overwatering and overfertilizing, but what the shaded turf needs is half the water and half the fertilizer that the sunny turf receives.
What are some other options for turfgrass with shade stress?
Here are options offered by turf experts and turf management companies:
- Raise mowing heights; even small amounts can significantly improve turf quality
- Increase the budget for a fungicide to reduce diseases, algae, moss; use the fungicide more often
- Reduce irrigation and fertilization in shady areas by 50%
- Consider plant growth regulators (PGRs); multiple applications at low rates can decrease the elongation of turf shoots
- Try supplemental lighting in small areas
- Switch to shade-tolerant turf
- Prune tree branches to at least 8-10 feet above ground
- Remove selective trees
- If all else fails, replace turf with shade tolerant plants, ground covers or mulches in the worst areas.
Another option is a shade study. Since the light that filters through the trees (or stadium roofs and adjacent buildings) is constantly changing by the day, season and time of day, a shade consultant can measure and analyze shaded areas.
Turf management companies like Commonwealth Sports Turf Services specialize in problem-solving these issues for field owners and organizers.
Even without the shade of nearby trees or structures, the weather impacts turf constantly through clouds, fog, smog, rain and looming global climate change. If the heavy rains of the first three weeks of May 2016 continue, Virginia will have its 11th rainiest May since the late 1800s.
Sports field owners are beginning to recognize the damage that global climate change can do to the turf on their playing fields, stadiums and golf courses.
So how should sports turf be managed when shade stress already affects the turf’s quality and predicted climate change exacerbates the stress? Article references are listed below for further reading. Consulting with a turf management firm will start the process of preparing for disastrous climate effects in the future.
Dr. R.R. Duncan, “Managing Turf With Reduced Light,” April 2001, http://sturf.lib.msu.edu/article/2001apr42.pdf
Dr. Wendy Gelernter and Dr. Larry J. Stowell, “Shade Versus Turfgrass: a No-Win Situation?” Golf Course Industry Magazine, Feb. 2008, http://www.golfcourseindustry.com/article/shade-versus-turfgrass–a-no-win-situation—research-/
“Growing Turf under Shaded Conditions,” UMass Extension, Center for Agriculture, https://ag.umass.edu/sites/ag.umass.edu/files/fact-sheets/pdf/growing_turf_shaded_conditions.pdf
Dr. John Sorochan, “Understanding, Assessing and Managing Shade Stress Problems.” Presented at Sustainable Turfgrass Management in Asia, Pattaya, 2014 http://www.files.asianturfgrass.com/2014_sorochan_shade.pdf
USDA Plant Hardiness Zone Map, http://planthardiness.ars.usda.gov/PHZMWeb/
National Weather Service – NOAA, www.weather.gov/akq/climatepns May 20, 2016