Turfgrass weed scientists commonly use visual ratings (VR) to assign a numerical value to a turfgrass or weed response. These ratings lack quantifiable numerical values and are considered subjective. Alternatives to VR, including line intersect analysis (LIA) and digital image analysis (DIA), have been used to varying extents in turfgrass research. Alternatives can be expensive, labor intensive, and can require extensive calibration and increased time for data acquisition. Minimal research has been conducted evaluating rating methods used in turfgrass weed science. Trials were conducted in 2007 and 2008 to evaluate ratings methods used to quantify large crabgrass populations as influenced by tall fescue mowing height (2.5, 5.1, 7.6, and 10.2 cm). Percent large crabgrass cover was assessed utilizing VR, LIA, and DIA to determine if differences existed among evaluation methods. Pairwise comparisons, Pearson's correlation, and linear regression were performed to compare evaluations. All rating methods were significantly correlated to one another. Differences of large crabgrass cover estimates existed between LIA and DIA data at all mowing heights and between VR and DIA data at the 7.6 and 10.2 cm mowing heights in 2007. Authors believe that shadows produced by the turf canopy at higher (≥ 7.6 cm) mowing heights increased DIA estimates of large crabgrass cover. At trial initiation in 2007, researchers did not capture calibration images because the methodology to eliminate a shadow influence using a standard digital image had not been published. Additional DIA calibration in 2008 corrected for canopy shadows, and no differences were observed in large crabgrass cover between all evaluation methods indicated by nonsignificance pairwise comparisons and estimated regression parameters. These data indicate VR are no different than LIA or DIA in estimating large crabgrass cover as affected by tall fescue mowing height.

During drought, golf course turf continues to receive golf cart traffic, which may compound conditions of drought stress. Our objectives in a 2‐yr field study were to evaluate responses in turf canopy variables of (a) green cover (GC) and (b) turf quality (TQ) from the impact of golf cart traffic during a 41‐d summer drought and subsequent 40‐d recovery without traffic on two cool‐season (C3) [Kentucky bluegrass (Poa pratensis L.) and perennial ryegrass (Lolium perenne L.)] and two warm‐season (C4) turfgrasses {buffalograss [Buchloe dactyloides (Nutt.) Engelm: syn. Bouteloua dactyloides (Nutt.) J.T. Columbus} and zoysiagrass (Zoysia japonica Steud.)} maintained at golf course fairway and rough mowing heights. Better drought tolerance of C4 than C3 turfgrasses resulted in higher TQ and GC of C4 turfgrasses during drought and faster recovery regardless of traffic or mowing height. Compared with nontrafficked plots at the end of drought, traffic at rough height reduced GC by 43% in C4 turfgrasses and 33% in perennial ryegrass, while traffic at fairway height reduced GC by 26% in C4 turfgrasses but had negligible effects on GC in C3 turfgrasses. Except for Kentucky bluegrass in year two, all turf species recovered from cart traffic stress during drought and returned to acceptable TQ and high GC upon rewatering in both years. Results indicate cart traffic during drought accelerates declines in TQ and GC, which vary among species and heights, and traffic will impact turf aesthetics more severely at rough than at fairway mowing heights, so golf course superintendents should monitor and manage traffic at rough heights more closely.

Core Ideas Early fall Proxy (ethephon) applications effectively suppress Meyer zoysiagrass seedheads in spring. Apply Proxy in late‐September when days are approximately 12 hours long to suppress zoysiagrass seedheads. Tank‐mixtures of Proxy with large patch fungicides reduce application labor and equipment costs. ‘Meyer’ zoysiagrass (Zoysia japonica Steud.) is used on golf courses throughout the transitional climatic zone because of its aesthetic and functional quality and tolerance to abiotic stresses. However, a key problem with Meyer zoysiagrass is that it produces seedheads in the spring that reduce aesthetics and increase golf course maintenance costs. The objective of this experiment was to quantify the efficacy of Proxy (ethephon) on Meyer zoysiagrass seedhead suppression at three locations when applied in fall before winter dormancy and in spring prior to seedhead production. The early fall application timing of Proxy provided > 90% suppression of zoysiagrass seedheads with < 10% injury. Late fall and spring Proxy applications provided little seedhead suppression. The early fall application timing that successfully suppressed Meyer zoysiagrass seedheads in our experiment was applied from 23 to 29 September across locations to 100% green zoysiagrass; on dates with a photoperiod of 11.9 to 12.1 h; and following the accumulation of < 14 cooling degree days (20°C base temperature). This research provides turf managers insight on how to best suppress Meyer zoysiagrass seedhead production.

Thermal heat has been utilized for nonselective weed control methods. These methods are highly variable in application and efficacy. One effective weed–seed-control determining factor is achieving the thermal death point of targeted weed seeds. The thermal death point varies by weed species, temperature, and exposure time. Our objective was to determine the thermal death point of large crabgrass, cock's-comb kyllinga, and Virginia buttonweed at short thermal exposure periods. Studies conducted utilized 5 and 20 s exposure periods for incremental range, 60 to 250 C temperatures. Sigmoid regression curves were used to predict weed seed mortality by temperature and exposure time. A significant interaction between exposure period and temperature occurred for each weed species. Weed species increased in susceptibility to 20 s thermal heat as follows: Virginia buttonweed < cock's-comb kyllinga < large crabgrass. Increasing thermal exposure time from 5 to 20 s reduced thermal temperature by 21 C to achieve 50% mortality for large crabgrass and by 10 C for cock's-comb kyllinga. Virginia buttonweed achieved 50% mortality at 99 C for 5 and 20 s exposure periods. These data indicate that at least 50% weed seed mortality can be achieved at 99 and 103 C for 20 and 5 s exposure periods, respectively, for these weed species.

Weed control by heat or flaming typically uses flames to burn small weeds, directed away from desired crops. This research studied an enclosed flaming system for weed control before turfgrass establishment. Field research trials were conducted to explore the efficacy of a PL-8750 flame sanitizer at two application timings. Treatments included various application methods of PL-8750 flame sanitizer and common thermal and chemical weed control methods. Data were weed control relative to the control treatment. Species evaluated included carpetweed, Virginia buttonweed, spotted spurge, large crabgrass, goosegrass, old world diamond-flower, cocks-comb kyllinga, and yellow nutsedge. Turfgrass establishment was not successful in summer but was successful in fall. Fall-application timing trials resulted in > 60% tall fescue establishment at 6 wk after seeding (WAS) for all treatments. Summer-application timing trials resulted in unacceptable turfgrass establishment (≤ 18%) for all evaluated turfgrass species at 6 WAS. Broadleaf and grassy weeds were better controlled compared with sedge weeds. Overall, solarization; covered, emerged-weed flaming; and double applications of covered, emerged-weed flaming were the most successful treatments. Solarization controlled carpetweed, Virginia buttonweed, spotted spurge, large crabgrass, and goosegrass > 80% at 6 WAS. Weed control across thermal treatments were equal to or greater than the comparison chemical treatment (dazomet at 389 kg ha−1). Results indicate thermal weed control has potential for reducing weed populations before turfgrass establishment.