Kentucky bluegrass divot resistance as affected by cultivar, trinexapac-ethyl, and soil cultivation

Athletic fields constructed with a high percentage of sand rely on the presence of above- and belowground turfgrass biomass to provide surface stability to athletes. As turfgrass plants are worn away during field use, their stabilizing effect is lost, increasing the potential for divoting. Excessive divoting results in poor footing and may increase the potential for athlete injury. The objectives of this research were to evaluate the effects of two trinexapac-ethyl (TE) treatment regimes and one cultivation procedure on the divot resistance, tiller density, belowground biomass, and turfgrass ground cover of nine Kentucky bluegrass (KBG) (Poa pratensis L.) cultivars under varying levels of simulated traffic. Trinexapac-ethyl (0.17 kg a.i. ha⁻¹) was applied every 28 d from either May–July or May–October. The cultivation treatment, which consisted of a combination of vertical mowing 1.3 cm below the soil surface and core cultivation, occurred in the spring of each year. Traffic was applied starting in late summer using a Brinkman traffic simulator. Treatments and KBG cultivars were evaluated for divot resistance by measuring the length of divots created using the head of a golf pitching wedge attached to the end of a weighted pendulum. Differences in divot resistance among KBG cultivars increased as traffic level intensified. The application of TE from May–July reduced divot length most relative to the control both years of the experiment (18 and 7% in 2006 and 2007, respectively). Tiller density and belowground biomass were increased by May–July application of TE by 9 and 8%, respectively, compared to the control. The application of TE from May–October and the cultivation treatment each reduced divot size in one of the two years. Results indicate that on fall-use KBG athletic fields with little to no play during the spring and summer, applying TE from May–July can increase divot resistance.