Research Articles continued
Influence of Fall Fertilization Programs on the Traffic Tolerance and Recovery of Sprigged Bermudagrass Varieties
Virginia Tech Researchers: Eric Reasor, Undergraduate Student; Mike Goatley Jr., Ph.D., Extension Turfgrass Specialist and Professor; Whitnee Askew, Research Technician; Shawn D. Askew, Ph.D., Associate Professor, Turfgrass Weed Science; and David McCall, Research Specialist (Departments of Crop & Soil Environmental Sciences and Plant Pathology, Physiology & Weed Science)
Many
athletic fields in the transition zone are established with bermudagrass because of its ability to withstand heavy traffic, as well as its rapid growth rate and high density. However, the ability to withstand heavy traffic during the first year of establishment is challenging due to the onset of winter dormancy in mid-fall of a typical football season. Foot traffic from athletes, along with overseeding competition, can limit first-winter bermudagrass survival. This research evaluated how lateseason nitrogen applications affected fall traffic tolerance and the quality of newly established bermudagrass, as well as spring greening and recovery.
Our research
We began our research in June 2010 at Virginia Tech’s Turfgrass Research Center. On June 18, research plots were established by sprigging shredded sod of three bermudagrass cultivars: ‘Patriot’, ‘Riviera’ and ‘Wayland’. ‘Patriot’ and ‘Riviera’ are both commercially available cultivars, while ‘Wayland’ is an experimental ecotype selected at Virginia Tech for its rapid spring greening and spring dead spot tolerance. At the time of planting, nitrogen was applied at 1 lb. N/1,000
ft2. Irrigation was applied to promote active growth, and the plots were mowed three times weekly at 1-1/4". Additional nitrogen was applied to all plots at 1 lb. N/1,000 ft2 per month in July and August. The fall fertilization treatments extended nitrogen applications into September and October. September fertilization was 1 lb. N/1,000 ft2, totaling 4 lbs. of nitrogen for the growing entire season. The October 2010 treatment received only 1/2 lb. N/1,000 ft2 due to a dormancy-inducing frost in the middle of the month. The July, August, September and October nitrogen fertilization treatments were all made on the first day of each month. Beginning on August 30 and ending on November 7, simulated traffic
12 | Virginia Turfgrass Journal May/June 2012 www.vaturf.org
(using a Brinkman traffic simulator) was applied at six events per week, serving as a typical fall football schedule. Ratings of visual coverage, quality and density were taken on October 18 and November 1. Visual quality, percent green cover and percent bare-ground ratings were taken in spring 2011.
Results to date
On July 2, only two weeks after planting, ‘Patriot’ achieved 50% coverage, whereas ‘Riviera’ and ‘Wayland’ had 37.5% and 23.8% coverage respectively (data not shown). On July 22, ‘Patriot’ coverage was 97.5%, ‘Riviera’ increased to 85%, and ‘Wayland’ was 72.5%. All grasses reached 95% or greater coverage by August 6, with Patriot covering the quickest, followed by ‘Riviera’, then ‘Wayland’. The more rapid establishment rate of ‘Patriot’ gives it an advantage over the other two varieties because ‘Patriot’ has a thicker canopy by the time fall traffic begins. This was supported by visual percent coverage ratings taken on October 18 (six weeks after the initial traffic treat-