Application of growth promoters or inhibitors and mowing height adjustment are potential means of improving the growth and performance of TifEagle bermudagrass [Cynodon dactylon (L.) Pers. × C. transvaalensis Burtt‐Davy] in a reduced light environment (RLE). A study was conducted in June to August 2001 and 2002 to examine the effects of growth factors and two mowing heights on TifEagle bermudagrass when grown at various hours of sunlight. Shade cloth (92%) was used at different intervals to obtain three sunlight hours, 12 h (0800–2000 h), 8 h (1000–1800 h), and 4 h (1200–1600 h), with an average 2‐yr daily light integral (DLI) of 41.1, 35.5, and 22.1 mol m−2 d−1, respectively. Sunlight hours were split by growth factor applications and mowing height. Growth factors included trinexapac‐ethyl [TE; 4‐(cyclopropyl‐alpha‐hydroxymethylene)‐3,5‐dioxo‐cyclohexanecarboxylic acid ethyl ester] at 0.0393 kg a.i. ha−1 every 3 wk, gibberellic acid (GA) at 0.059 kg Gibberellin A3 (GA3) ha−1 every 2 wk, additional nitrogen (+N) application of 24.5 kg N ha−1 every 2 wk, and an untreated check. Turf was mowed at 3.2 or 4.7 mm daily. Acceptable turf quality (TQ) followed all growth factor treatments receiving the 12 and 8 h of sunlight, except GA. For the 4‐h sunlight treatments, only plots treated with TE and mowed at 4.7 mm resulted in acceptable TQ. The +N applications increased percentage lateral regrowth (RG) of TifEagle bermudagrass by 7 to 10% compared with other growth factors. Across all sunlight treatments, TE increased total shoot chlorophyll by as much as 19 and 42% compared with untreated, +N, and GA‐applied plots. The 3.2‐mm mowing height increased total nonstructural carbohydrates (TNC) by 19% compared with TifEagle mowed at 4.7 mm. Growth factors, including TE, +N, or GA, did not improve TNC concentration. In a RLE, methods of improving the growth and performance of TifEagle bermudagrass include TE applications and raising the height of cut to 4.7 mm. Overall, the growth and performance of TifEagle bermudagrass reduced greatly in the 4‐h sunlight treatments compared with 12‐ and 8‐h sunlight treatments.

‘TifEagle’ bermudagrass [Cynodon dactylon (L.) Pers. × C. transvaalensis Burtt‐Davy] is a fine textured hybrid bermudagrass used for golf course putting greens in the subtropical and tropical regions of the world. The growth and performance of TifEagle and other bermudagrass often decline in reduced light environments (RLEs). This study quantified a daily light integral (DLI; mol m−2 d−1) required to maintain commercially acceptable TifEagle bermudagrass maintained under golf green conditions. Three levels of shade, none, low, and high (0, 41, and 92%), were applied to mature TifEagle bermudagrass during morning (sunrise to 1100 h) and afternoon (1500 h to sunset) hours, allowing full irradiance from 1100 to 1500 h to mimic a golf green situation where trees or structures are adjacent to, but rarely directly overhead. The study was performed for 8 wk in June to August 2001 and 2002. An average minimal DLI of 32.6 mol m−2 d−1 was needed to maintain commercially acceptable TifEagle turf quality (TQ ≥ 7). Other plant responses measured included percentage lateral regrowth (RG), total shoot chlorophyll, and total nonstructural carbohydrates (TNC). These responses declined significantly when the DLI ≤ 32.6 mol m−2 d−1 Differences in diurnal shade exposure occurred. High afternoon shade reduced TifEagle bermudagrass TQ, percentage lateral RG, shoot chlorophyll, and TNC by 3.0 rating units and 17, 39, and 27%, respectively, compared with no afternoon shade (NSA). High morning shade reduced TQ, percentage lateral RG, and shoot chlorophyll by 1.5 rating units and 11 and 16%, respectively, compared with no morning shade (NSM). Overall, afternoon shade applications were more detrimental to TifEagle bermudagrass growth and performance compared with morning shade.

Bahiagrass is used for roadsides, pastures, and lawns in the southeastern United States mainly because of drought and nematode tolerance. Metsulfuron is a sulfonylurea herbicide, which selectively controls bahiagrass in bermudagrass. Certain cultivars of bahiagrass were observed to be tolerant to recommended rates of metsulfuron. Therefore, research was conducted to investigate the susceptibility of five major bahiagrass cultivars to metsulfuron applied at increasing rates to 42 g ai/ha. Five bahiagrass cultivars were evaluated: ‘Pensacola’, ‘Tifton-9’, ‘Argentine’, ‘Common’, and ‘Paraguayan’. Argentine, Common, and Paraguayan cultivars showed a four- to fivefold increased tolerance to metsulfuron compared with Pensacola. Because of yearly inconsistencies, results for Tifton-9 were inconclusive.

Annual bluegrass (Poa annua L.) (ABG) is an invasive weed in creeping bentgrass (Agrostis stolonifera L.) (CBG) golf course fairways and tees. Plant growth regulators (PGRs) like flurprimidol (FL) are often applied to these areas to manage shoot growth and minimize ABG encroachment. This two‐year field study evaluated the effects of various FL, trinexepac‐ethyl (TE), and FL + TE tank‐mix combinations applied monthly from May through October to a mature CBG research fairway containing > 30% ABG prior to PGR initiation. After two consecutive years of PGR applications the most effective treatments for reducing ABG populations were FL alone (0.28, or 0.56 kg a.i./ha) or the FL + TE (0.56 + 0.06 kg a.i./ha) tank‐mix which reduced the ABG populations from initial levels by 78, 74, and 87% respectively. PGR effects on visual color and quality were not significant when averaged across both study years. These results demonstrate that even where rather large, > 30%, ABG populations exist, monthly FL applications throughout the growing season can gradually reduce ABG to tolerable, <10%, levels without the risk for rapid turf cover losses which can result in substantial turf voids.

Increased soil moisture and temperature along with increased soil microbial and root activity during summer months elevate soil CO2 levels. Although previous research has demonstrated negative effects of high soil CO2 on growth of some plants, little is known concerning the impact high CO2 levels on creeping bentgrass (Agrostis palustris Huds.). The objective of this study was to investigate effects of varying levels of CO2 on the growth of creeping bentgrass. Growth cells were constructed to U.S. Golf Association (USGA) greens specification and creeping bentgrass was grown in the greenhouse. Three different levels of CO2 (2.5%, 5.0%, and 10.0%) were injected (for 1 minute every 2 hours) into the growth cells at a rate of 550 cm3·min-1. An untreated check, which did not have a gas mixture injected, maintained a CO2 concentration <1%. Gas injection occurred for 20 days to represent a run. Two runs were performed during the summer of 1999 on different growth cells. Visual turf quality ratings, encompassing turf color, health, density, and uniformity, were evaluated every 4 days on a 1-9 scale, with 9 = best turf and <7 being unacceptable. Soil cores were taken at the end of each run. Roots were separated from soil to measure root depth and mass. Turf quality was reduced to unacceptable levels with 10% CO2, but was unaffected at lower levels over the 20-day treatment period. Soil CO2 ≥2.5% reduced root mass and depth by 40% and 10%, respectively.