The comparative competitive ability of thirteen Agrostis stolonifera cultivars to Poa annua

Poa annua has been an increasing problem on Agrostis stolonifera putting greens, especially with the lowering of the mowing height into the 2.5 to 3.8 mm range. Recently a number of new Agrostis stolonifera cultivars have been released for use on putting greens. This investigation assesses the relative competitive ability of 13 Agrostis stolonifera cultivars under very closely mowed putting green cultural regime of 3.2 mm. The relative competitive ability is assessed by the transplanting of mature monostands of Poa annua into mature turfs of each of the 13 replicated Agrostis stolonifera cultivars. Four Agrostis stolonifera cultivars ranked superior in competitiveness with Poa annua, including Penn G2, Penn G6, Seaside II and Penn A1. Ranking lowest in aggressiveness under the very closely mowed conditions were Penncross and Pennlinks. Those Agrostis stolonifera cultivars sustaining shoot densities above 2000 dm -2 exhibited the most competitiveness in suppressing the Poa annua content in polystands. These findings suggest that significant cultural control of Poa annua can be accomplished on closely mowed putting greens by the selection of certain Agrostis stolonifera cultivars that can sustain very high shoot densities under close mowing condition.