Improvement of Traffic Tolerance and Spring Recovery of Sprigged Bermudagrasses by Fall Fertilization.

Bermudagrass (Cynodon spp.) is a popular athletic field turfgrass in the transition zone due to its ability to withstand traffic, rapid growth, and high density.  However, the ability to withstand traffic during the first year of establishment is challenging due to winter dormancy in mid-fall of a typical football season.  This research is evaluating first and second season traffic tolerance of three vegetatively-established bermudagrasses (‘Patriot’, ‘Riviera’, and an experimental ecotype, ‘Wayland’) to varying levels of fall Nitrogen fertilization.  Plots of 9.3 m² were established at the Virginia Tech Turfgrass Research Center on 16 June 2010 and 13 June 2011 using sprigs generated from 0.9m² of shredded sod from each cultivar.  All plots received 49 kg ha^-1 N per month in June, July and August.  Plots were mowed three times weekly at 2.5 cm and irrigated to promote active growth.  A traffic simulator was applied weekly to one-half of the bermudagrass plots to simulate the traffic of six football games per week from late August through early November.  Nitrogen fertilization treatments were applied perpendicular to traffic and non-trafficked treatments at 49 kg ha^-1 monthly from June through August, June through September, and June through October.  Rhizome samples were collected in November of each year for total nonstructural carbohydrate (TNC) analysis. Normalized Difference Vegetation Index and Ratio Vegetation Index measurements were taken in October and April of each year.  Extending N fertilization timing enhanced NDVI/RVI responses as well as visual ratings of fall and spring color responses and turf recovery in 2010-11, but not in the comparatively milder winter of 2011-12.   Turfgrass variety, fertility, or traffic had no measurable effect on stem TNC concentration.