Effects of Plant Growth Regulators and Biostimulants on Summer Bentgrass Decline.

Summer decline is a major concern of superintendents growing creeping bentgrass (Agrostis stolonifera L.)on putting greens across the country. The objectives of this study were to investigate whether the application of selected plant growth regulators (PGRs) and biostimulants to a bentgrass putting green would enhance turf quality during summer months, and to determine whether these products would help alleviate summer bentgrass decline by delaying or suppressing leaf senescence. The study was performed on a 4-year ‘Penncross’ bentgrass green built to United States Golf Association greens specifications at Hort Farm II, North Brunswick, NJ in 2006-2007. Turf was foliar sprayed with a trademarked product Turf Vigor (47.75 L/hectare), a seaweed extract containing cytokinins (19.10 L/hectare) and trinexapac-ethyl (0.40 L/hectare) from late June to early September in a 2-wk interval. All three treatments improved turf quality during summer compared with both a nutrient control (half-strength Hoagland’s nutrient solution) and a water control. Leaf senescence was mitigated by the three treatments, as manifested by higher chlorophyll content, photosynthesis rate, green leaf biomass and leaf area index in the treated plots during summer stress period (July and August). Our results suggest that proper use of certain stimulants or PGRs may help alleviate summer bentgrass decline in the transition area.