Hollow tine cultivation is a routine practice on golf course putting greens, where the tine entry angle normally is 90°. Effects of various tine entry angles impacting putting green surfaces have not been investigated. The hypothesis was that different tine entry angles during cultivation would impact a greater area of the soil profile by enhancing water infiltration rates, reducing localized dry spots, and enhancing turf quality. Therefore, a 2-year field study in 2003 and 2004 was conducted to determine the impact of core cultivation tine entry angle on `Crenshaw' creeping bentgrass (Agrostis stoloniferous var. palustris). Treatments included three angles of hollow tine entry at 50°, 70°, and 90° and an untreated plot without cultivation. Manual cultivators consisted of four 1/4-inch- and 1/2-inch-diameter hollow tines 3 inches in length, spaced 2 inches apart. Treatment applications were in April, May, September, and October. Measurements included visual turfgrass quality (TQ), molarity ethanol droplet test (MED), and water infiltration. No treatment (control, 50°, 70°, 90°) effects in years I and II for TQ were noted. MED scores in May were 23% higher than in August and September. Tines of 1/2-inch diameter reduced soil hydrophobicity (MED) 6% compared to tines of 1/4-inch-diameter tines. Tines of 50°, 70°, and 90° had 129%, 163%, and 211% greater water infiltration than the untreated, respectively.
Christian M. Baldwin, Haibo Liu and Philip J. Brown
Robert Andrew Kerr, Lambert B. McCarty, Philip J. Brown, James Harris and J. Scott McElroy
Summer annual grassy weeds such as goosegrass (Eleusine indica L. Gaertn.) continue to be problematic to control selectively with postemergence (POST) herbicides within turfgrass stands. In recent years, reduced performance by certain herbicides (e.g., foramsulfuron), cancellation of goosegrass-specific herbicides (e.g., diclofop-methyl), and cancellation and/or severe use reductions of other herbicides [e.g., monosodium methanearsonate (MSMA)] have limited the options for satisfactory control and maintenance of an acceptable (≤30% visual turfgrass injury) turfgrass quality. Currently available herbicides (e.g., topramezone and metribuzin) with goosegrass activity typically injure warm-season turfgrass species. The objectives of this research were to evaluate both ‘Tifway 419’ bermudagrass [Cynodon dactylon (L.) Pers. ×Cynodon transvaalensis Burtt-Davy] injury after treatment with POST herbicides, and to determine whether irrigating immediately after application reduces turfgrass injury. Treatments were control (± irrigation); topramezone (Pylex 2.8C; ± irrigation); carfentrazone + 2,4-D + dicamba + 2-(2-methyl-4-chlorophenoxy) propionic acid (MCPP) (Speedzone 2.2L; ± irrigation); carfentrazone + 2,4-D + dicamba + MCPP in combination with topramezone (± irrigation); metribuzin (Sencor 75DF; ± irrigation); mesotrione (Tenacity 4L; ± irrigation); simazine 4L (±irrigation); and mesotrione + simazine (± irrigation). Irrigated treatments were applied immediately with a hand hose precalibrated to apply 0.6 cm or 0.25 inch (≈6.3 L). Visual turfgrass injury for combined herbicide treatments for the irrigated plots was 6% 4 days after treatment (DAT), 12% 1 week after treatment (WAT), 17% 2 WAT, and 6% 4 WAT, whereas nonirrigated plots had turfgrass injury of 14% at 4 DAT, 31% 1 WAT, 35% 2 WAT, and 12% 4 WAT. Irrigated pots had normalized differences vegetative indices (NDVI) ratings of 0.769 at 4 DAT, 0.644 at 1 WAT, 0.612 at 2 WAT, and 0.621 at 4 WAT, whereas nonirrigated plots had the lowest (least green) turfgrass NDVI ratings of 0.734 at 4 DAT, 0.599 at 1 WAT, 0.528 at 2 WAT, and 0.596 at 4 WAT. These experiments suggest turfgrass injury could be alleviated by immediately incorporating herbicides through irrigation.