Justin H. Springer and Francis B. Lopez, Biological and Chemical Sciences, The University of the West Indies, Cave Hill Campus, Bridgetown, Barbados
Zoysia grasses generally show poor turf recovery from damages sustained under sports field conditions. In the current study, Zoysia japonica (possibly an ecotype derived from cultivar ’El Toro’) was observed as a rapidly expanding weed in cultivated Bermuda grass (Cynodon dactylon, cultivar ‘Princess-77’) turf on a heavily-utilized sports field at the University of the West Indies, Cave Hill Campus, Barbados. To further characterize the wear tolerance of this Zoysia japonica turf, the effects of wear on turf growth and quality were investigated for potted plants under different clipping frequencies (once, twice per week), rooting media (sand, sand-soil) and fertilizers (NPK 24:8:16, 14:10:27). The effects of fertilizer application rates (0.5, 1.0, 2.0 × recommended concentration) were examined in a follow-up study. Turf was subjected to simulated wear by the action of the rotating arm and cutting blade (1.8 cm long) of a ceramic tile hole-cutter (4 cm radius) fitted to a Power Drill. The wear treatment was applied for 3 seconds at 3 locations per pot on two occasions (7 or 14 days apart). Turf green cover % and greenness index were reduced to a greater extent by the wear treatment in the sand-soil compared to the sand rooting medium, but recovery rates appeared to be similar in both media. Fertilizer effects on wear tolerance were not consistent and beneficial effects of a lower N:K fertilizer ratio may be restricted to the early stages after the initial wear treatment. Turf height was reduced at the higher clipping frequency and was significantly affected by the wear treatment only at the lower clipping frequency. Green cover % was strongly correlated with turf clipping height (co-variate) in wear treated pots. Information provided by this study may be useful for guiding management decisions with regard to possible expansion of Zoysia japonica on sports fields.