Thatch is a layer of partially decomposed organic matter between green shoot tissue and the soil surface, and mat is thatch partially intermixed with topsoil. Excessive thatch-mat layering (.2.54 cm) is generally detrimental to turfgrass management, and numerous techniques including various mechanical and topdressing regimes, have been attempted to reduce its severity. This factorial experiment investigated the effectiveness of combining mechanical-biological and topdressing treatments for controlling thatch-mat levels in an established USGA-specified golf green planted with 'A-1' creeping bentgrass [Agrostis stoloniferous L. var. palustris (Huds.)]. Two levels of topdressing were used, and the mechanical-biological treatments included vertical mowing at two different depths and timings, core cultivation, grooming, a biological granular supplement (Thatch-X), and combinations of core cultivation with grooming and/or vertical mowing. Differences among the mechanical-biological treatments were detected following 2 consecutive yearly applications. Thatch-mat depth (mm) was 12 to 15% greater for Thatch-X and topdressing alone compared with other treatments. Organic matter content (g kg 21 ) increased 32% for the untreated and decreased 19% for core cultivation combined with vertical mowing and grooming, whereas all other treatments maintained pre-study levels. Compared with the untreated, surface hardness was reduced |9% for all treatments using core cultivation, while water infiltration rates increased 127 to 168%. Vertical mowing treatments improved water infiltration rates by 40 to 65%. Turfgrass quality was not greatly impacted by the mechanicalbiological treatments as ratings ranged from 8.4 to 10.0. However, mower scalping and dry spots contributed to unacceptable or only marginally acceptable turfgrass quality (6.4-7.2) for the untreated by the end of the study. Compared with topdressing alone, ball roll distance was decreased 6% by vertical mowing 7 days after treatment (DAT) and 5 to 8% by core cultivation up to 14 DAT. Sand topdressing alone was insufficient for managing thatch-mat levels in an established creeping bentgrass golf green.

gressive horizontal growth quickly develops undesirable excessive thatch-mat layering. Excessive (Ͼ1.3 cm) thatch and mat layering of turfgrass is consid-Thatch, a tightly intermingled layer of living and dead ered undesirable because it reduces hydraulic conductivity, water infiltration, increases localized dry spots and pest problems, and reduces stems, leaves, and roots of grass, develops between the pesticide effectiveness and turf tolerance to temperature extremes. green turfgrass vegetation and soil surface. It is formedThe objective of this 2-yr study was to determine the efficacy of primarily from periodically sloughed roots, intact fitopdressing alone and in combination with several mechanical and brous roots, horizontal stems (stolons and rhizomes), biological methods to control thatch-mat accumulation in a newly nodes, crown tissue, and vascular strands of stems and established 'L-93' creeping bentgrass [Agrostis stolonifera L. var palleaf sheaths (Engel, 1954;Roberts and Bredakis, 1960; ustris (Huds.) Farw.] sand-based golf green. Mechanical and biological Hurto et al., 1980). Thatch accumulation occurs when methods included vertical mowing at various depths and timings, core the production rate of organic matter exceeds the decultivation, grooming, a biological thatch control agent (Thatch-X), composition rate (Beard, 1973). Any climatic, edaphic, and combinations of core cultivation with grooming, core cultivation or biotic factor that stimulates excessive plant growth with vertical mowing, and core cultivation combined with grooming and vertical mowing. No treatment prevented thatch-mat accumula-Center; J.J. Camberato,

Annual bluegrass (Poa annua L.) can be a troublesome weed to control in established turfgrass stands; it has developed herbicide resistance after repeated use of products with similar modes of action, and several new herbicides have been registered for use on turfgrasses. Four field studies were conducted near Clemson, S.C., from 2003 through 2005 to evaluate postemergence annual bluegrass control in dormant, nonoverseeded bermudagrass [Cynodon dactylon (L.) Pers.] turf using various herbicides applied in either December or February of each year and rated in the spring. Annual bluegrass control can be accomplished in dormant, nonoverseeded bermudagrass turf using a wide range of products applied in either December or February. Flazasulfuron, foramsulfuron, glufosinate, glufosinate + clethodim, glufosinate + glyphosate, glyphosate + clethodim, glyphosate + diquat, pronamide, rimsulfuron, and trifloxysulfuron provided 87% or greater annual bluegrass control regardless of application timing. Imazaquin and simazine controlled annual bluegrass greater than 85% when applied in December but less than 80% when applied in February. Glyphosate provided 93% annual bluegrass control when applied in February but only 72% control with December applications. No detrimental effects on bermudagrass spring greenup were observed for any herbicide treatment or application time. The availability of several effective herbicide options with differing modes of action provides turfgrass managers with the opportunity to use herbicide rotations that may prevent, or at least delay, the development of resistant annual bluegrass populations to these chemical products.

The sedge genus Kyllinga consists of 40 to 45 species distributed in tropical, subtropical, and warm temperate regions around the world (KUkenthal 1936; Tucker 1987). This genus of low rhizomatous perennials or cespitose annuals is classified in the large cosmopolitan family Cyperaceae. Many Kyllinga species are considered weedy (Holm et al. 1979; Tucker 1987), while Kyllinga nervosa Steudel is considered an important forage plant in Africa (McNaughton 1985).

Plant growth regulators (PGRs) improve turf color by inhibiting leaf growth and may reduce fertilization requirements of bermudagrass [Cynodon dactylon (L.) Pers. × C. transvaalensis Burtt‐Davy] golf greens by reducing nutrients removed through clipping collection. To test this hypothesis, growth, color, and nutrient allocation of ‘TifEagle’ bermudagrass maintained at 3.2 mm were investigated in field experiments conducted in Clemson, SC, from April to August in 2003 and 2004. Ammonium nitrate was applied at 6, 12, 18, or 24 kg N ha−1 wk−1 with a PGR, trinexapac‐ethyl {[4‐(cyclopropyl‐[α]‐hydroxymethylene)‐3,5‐dioxo‐cyclohexane carboxylic acid ethyl ester]} (TE), at 0 or 0.05 kg a.i. ha−1 3 wk−1 Turf required 18 to 24 kg N ha−1 wk−1 from May to June and ≤12 kg N ha−1 wk−1 from July to August to maintain acceptable color (≥7, 1–9 scale). Trinexapac‐ethyl initially caused discoloration but bermudagrass recovered and had color enhanced 10 to 25% from nontreated. Trinexapac‐ethyl reduced clippings 67% from nontreated while clippings, percentage of lateral regrowth, and aerification recovery increased with N rate. Bermudagrass treated with TE had similar root mass to nontreated but 5% greater stolon and rhizome mass, 18% higher chlorophyll concentration, up to 67% reduced lateral regrowth, and up to 38% reduced aerification recovery. Trinexapac‐ethyl reduced leaf N, P, K, Mg, S, and Fe concentrations 10 to 25% and increased rhizome concentrations 8 to 36%. Nutrients recovered through clippings were reduced ≈70% from TE applications while TE‐treated turf had increased N, P, K, Ca, Mg, S, Mn, and Fe retention in stolons and rhizomes. Overall, TE enhanced color while reducing nutrient translocation from rhizomes to leaves, thus increasing bermudagrass nutrient retention.

Dwarf bermudagrass (Cynodon dactylon × C. transvaalensis Burtt‐Davy) and creeping bentgrass (Agrostis stolonifera L.) are planted for golf greens in the U.S. transition zone, but management regimes, such as the use of a plant growth regulator (PGR), often vary for long‐term culture of the two species. The objective of this experiment was to investigate application regimens of the PGR trinexapac‐ethyl (TE), on growth, quality, and performance of creeping bentgrass and bermudagrass putting greens in Clemson, SC. ‘L‐93’ creeping bentgrass and ‘TifEagle’ bermudagrass putting greens, established in summer 2002 and mowed at 3.2 mm, received TE over 12 wk in three regimens: 0.017 kg ha−1 wk−1, 0.033 kg ha−1 2 wk−1 (biweekly), or 0.05 kg ha−1 3 wk−1 (triweekly) from May to August 2003 and 2004. Creeping bentgrass was not discolored from TE, but unacceptable bermudagrass discoloration (>20%) occurred on one, two, and six dates for weekly, biweekly, and triweekly regimens, respectively. All TE regimens reduced bermudagrass clippings approximately 50% from nontreated bermudagrass across all dates, while creeping bentgrass clipping reductions, approximately 20 to 35% from nontreated grass, were inconsistent. The root masses of both species treated with TE regimens were similar to nontreated turf. Bermudagrass aerification recovery was reduced on two, two, and four dates after weekly, biweekly, and triweekly TE regimens, respectively. All TE regimens increased morning and evening bermudagrass golf ball roll distance approximately 25 cm from morning distances of nontreated turf.

This research examined the effect of duration of the warm cycle and number of fluctuating temperature/light cycles on goosegrass seed germination. Less than 10% goosegrass seed germination occurred at constant temperatures of 20, 25, and 35 C, while 99% germinated at daily fluctuating temperature regimes of 20 C for 16 h and 35 C for 8 h with light. Increasing the number of fluctuating temperature cycles increased goosegrass seed germination. Fluctuating temperature cycles with 22 h at 20 C and 2 h at 35 C with light strongly stimulated germination, but not as much as the cycle with 8 h at 35 C. Goosegrass seed germination ceased once the fluctuating temperature regime was discontinued, and constant 20 C with 8 h light daily was reimposed. Germination occurred only on resumption of fluctuating temperature cycles. Seed incubated for several weeks in a moist environment at constant 20 C had 81 to 91% germination with two cycles of 20 C for 16 h and 35 C for 8 h, compared to 14% for fresh seeds.

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.