FIELD APPARATUS FOR TESTING ALLELOPATHY OF ANNUAL BLUEGRASS ON CREEPING BENTGRASS

Golf-course superintendents have long observed the competitive nature of annual bluegrass (Poa annua L.) as a weed on creeping bentgrass [Agrostis stolonifera L. var. palustris (Huds.) Farw.] putting greens. Allelopathy has been suggested as a contributing factor in this competitiveness. This study tested the allelopathy hypothesis under putting-green conditions using a modified field approach of the conventional stair-step experimental procedure. Annual blue-grass and creeping bentgrass sand putting greens, each 297 m2, were established, and leachate from these greens was used to irrigate replicated sand-based creeping bentgrass test greens. Moisture sensing and irrigation of the test plots were under continuous electronic control. The leachate sampling and delivery system functioned flawlessly throughout the 2-yr period, in spite of weather extremes (> 40-degrees-C). After two growing seasons of monthly monitoring, no consistent effects on turf color, foliar ground cover, shoot density, or disease incidence were found in the test green to indicate allelopathy.