Tuesday, November 14, 2006

Creeping bentgrass divot recovery as affected by various plant growth regulators.

Cale Bigelow, Purdue University, 915 West State St., 915 West State St., West Lafayette, IN 47907-4773, United States of America, B. Todd Bunnell, Suite 600, SEPRO Corporation, 11550 N Meridian Street, Carmel, IN 46032, J.E. Kaminski III, University of Connecticutt, 1376 Storrs Road, Unit 4067, Storrs, CT 06269, and Glenn Hardebeck, Purdue Univ., 915 West State St., 915 West State St., West Lafayette, IN 47907-4773, United States of America.

Creeping bentgrass (Agrosits stolonifera Huds. Farw.) fairways and tees are often subject to frequent devoting. These voids can negatively impact the playability of the area and render the turf vulnerable to annual bluegrass (Poa annua L.) encroachment. Turf managers often apply plant growth regulators (PGRs) to these areas to manage clippings and minimize annual bluegrass encroachment. Although PGRs generally suppress vertical shoot growth, the effect of various PGRs on lateral growth has not been well documented.  This two-year field study conducted on mature bentgrass research fairways in CT and IN evaluated the effects of three commercially available PGRs; fluprimidol (FL), paclobutrazol (PB) and trinexepac-ethyl (TE), applied at a various recommended label rates for their effects on lateral growth. Both FL and PB were applied at 0.28, 0.43, 0.56 kg a.i. ha-1, TE was applied at 0.06 kg a.i. ha-1 in year 2 only. Simulated divots, 5 cm diam., were removed and PGR applications started in mid-May and continued for three dates, 28 days apart. Regrowth was measured weekly for eight weeks using digital image analysis. In both years of the study PGR effects were generally inconsistent, probably due to weather and irrigation factors. On some measurement dates higher, 0.43 and 0.56, rates of PB and FL slightly suppressed regrowth. These data indicate that where divot recovery is a serious concern, higher rates of FL or PB ³ 0.38 kg a.i. ha-1 may slow divot recovery. However, weather factors and the seasonal health of the bentgrass probably plays a larger role.