Persisting drought conditions in California are limiting water allocation for golf course irrigation. A study was conducted at the University of California, Riverside to determine if products including trinexapac-ethyl (TE), a surfactant (Revolution), and nitrogen (N) fertilizer [Gro-Power (5-3-1); SeaBlend (12-4-5) + StressRX (6-0-2) + XP Extra Protection (5-0-0); YaraLiva (15.5-0-0); Turf Royale (21-7-14); each applied at 25 g N m -2 yr -1 ) could enhance quality of 'Princess 77' bermudagrass (Cynodon dactylon L. Pers.) irrigated at 53 or 92% turfgrass evapotranspiration (ET c ) under fairway conditions. Product and irrigation treatments were applied from May through October 2016 and 2017. Every 2 wk, plots were evaluated for visual quality, normalized difference vegetation index, soil volumetric water content using time domain reflectometry, and percent green cover using digital image analysis. Root samples were collected in November of both years, and fall color retention and spring green-up were assessed using digital image analysis. At 92% ET c replacement, visual quality was highest in plots that received TE and surfactant. Although no differences were found among fertilizer treatments, fertilization alone was able to sustain visual quality at a minimally acceptable level at 92% ET c . Surfactant had the greatest positive effect on turf irrigated at 53% ET c , whereas TE did not improve visual quality on the same plots. Overall, results indicate that regular applications of either Revolution surfactant or SeaBlend + StressRX + XP Extra Protection can sustain bermudagrass visual quality at 53% ET c .

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The objective of this study was to evaluate the effect of the supplemental lighting of cucumber with sodium pressure lamps (HPSs) and light-emitting diodes (LEDs) on photosynthetic efficiency and yield in autumn–winter cultivation. Cucumber plants of the ‘Svyatogor’ F1 midi-cucumber parthenocarpic type cultivar were grown on mineral wool mats in three compartments, differing only in the type of light, i.e., (1) HPS top lighting (HPS) in the first compartment, (2) HPS top lighting and LED panel interlighting (HPS + LED) in the second compartment and (3) LED top lighting and inter-row LED panels (LED) in the third compartment. The photosynthetically active radiation was the same in each compartment. The study showed that the highest commercial yields of cucumber could be achieved under LED light (top and inter-row). The chlorophyll content in the leaf blade of younger leaves was higher in plants under LED lighting. This type of lighting also had a positive effect on the gas exchange of plants (net carbon assimilation, stomatal conductance, transpiration). LED and HPS + LED lighting increased the chlorophyll a fluorescence parameters, such as Fs, Fm’ and vitality index (PI), in both younger and older leaves, which also increased the fruit yield in the tested combinations.

Golf courses in coastal regions of northern California are often faced with severe injury caused by pacific shoot-gall nematodes (Anguina pacificae) on their annual bluegrass (Poa annua) host in putting greens. For years, fenamiphos was used for mitigating disease outbreaks until its registration was withdrawn in 2008. An alternative product containing azadirachtin was intended for nematode suppression. Still, it required repeated applications throughout the year with questionable efficacy, making attempts to lessen the impact of the pathogen costly. This study evaluated fluopyram as a novel nematicide for control of pacific shoot-gall disease. Various application frequencies and rates were tested at several golf courses affected by the nematode. Results revealed that fluopyram applied once at 0.22 lb/acre reduced the number of new shoot-galls and improved annual bluegrass appearance for several months. Increased rates and application frequency occasionally improved the efficacy further. Although the visual quality of turf treated with this plant protection compound was tremendously enhanced, and the number of new shoot-galls was reduced, rarely a significant effect was observed on the population density of several soil-dwelling plant-parasitic nematodes, including pacific shoot-gall nematode. It is hypothesized that fluopyram did not move significantly past the thatch layer and into the soil. However, it effectively reduced the ability of pacific shoot-gall nematode juveniles to induce new shoot galls. Due to its long half-life, it likely protected against both new nematode infections and dissemination of pacific shoot-gall nematode when the shoot-galls decomposed.

Positive effects on plant health provided by quinone outside inhibitors (QoI) and other fungicide classes have been previously reported in turfgrass and other agricultural crops. However, most of the research was conducted under controlled environmental rather than field conditions. Two field and one greenhouse experiments were conducted and repeated in southern California from 2011-2013 to test the ability of selected fungicides to retain or improve creeping bentgrass (Agrostis stolonifera L.; CBG) quality and rooting characteristics when exposed to drought stress induced by multiple abiotic stressors, including, heat and traffic. Fungicide treatments were applied on 14-d or 28-d intervals prior to and during implemented stress periods for a total of 2-5 applications and consisted of azoxystrobin, chlorothalonil + acibenzolar-S-methyl (ASM), fluoxastrobin, aluminum tris, penthiopyrad, pyraclostrobin, pyraclostrobin + boscalid tested against a nontreated control (NTC). No disease symptoms were present in any trial site, but the presence of turfgrass pathogens was not determined. Although increased root diameter in comparison to NTC was observed in plants treated with azoxystrobin and pyraclostrobin + boscalid, and increased root volume was observed in pyraclostrobin + boscalid in the greenhouse study, no significant differences in rooting characteristics were found in the field studies. Moreover, none of the fungicide treatments improved turf quality or normalized difference vegetation index (NDVI) in any of the experiments. Results imply that fungicides offer little to no secondary benefits in regard to abiotic stress such as drought alleviation in arid environments, when disease pressure is minimal or absent.

Decreased stand uniformity together with reduced aesthetics and playability caused by annual bluegrass (Poa annua) intrusion in creeping bentgrass (Agrostis stolonifera) putting greens is one of the major problems that golf course superintendents face with managing newer playing surfaces. Few herbicides are registered for selective control of annual bluegrass in creeping bentgrass greens, and the risk of herbicide resistance remains an issue, thus use of plant growth regulators (PGRs) is still the primary method of annual bluegrass suppression. This study was conducted to evaluate eight PGR treatments, employed as a series of 15 consecutive, biweekly applications to suppress annual bluegrass encroachment in ‘Pure Distinction’ creeping bentgrass maintained as a golf course putting green in Los Angeles, CA. Best annual bluegrass suppression was observed with products containing flurprimidol (FP) at 0.256 lb/acre, paclobutrazol (PB) at 0.119 lb/acre, or three-way mixture of FP, trinexapac-ethyl (TE), and PB (FP+PB+TE) at 0.055, 0.014, and 0.055 lb/acre, respectively. Although all treatments caused some significant creeping bentgrass injury, which increased over time, PB at 0.119 lb/acre and FP+PB+TE at 0.055, 0.014, and 0.055 lb/acre, respectively, appeared to be safest among effective treatments. Additionally, those treatments caused significantly darker green turf, which may be desirable on putting greens. This research confirms the potential of PGR use to limit annual bluegrass infestation on creeping bentgrass greens in a Mediterranean climate and reveals the most effective treatments that could be used in a putting green maintenance program.

Wetting agents have been reported to alleviate localized dry spot and save water while maintaining turf quality at an acceptable level. However, limited research has been conducted on comparing the effects of different wetting agent products. A study was conducted from May to October in 2018 and 2019 in Riverside, CA to evaluate 10 wetting agent treatments on performance of 'Tifway II' hybrid bermudagrass [Cynodon dactylon (L.) Pers. × C. transvaalensis Burtt Davy] under deficit irrigation at three reference evapotranspiration (ET o ) levels: 45, 55, and 65% ET o . Ten wetting agent treatments were selected based on manufacturer recommendations. Plots were evaluated for visual turf quality, percent green cover (PGC), dark green color index, normalized difference vegetation index (NDVI), soil volumetric water content, soil moisture variability, and proline content in dry-leaf samples. Wetting agent treatments improved turf quality and PGC, and decreased soil moisture variability. Moreover, up to 16% increase in soil moisture levels was observed on treated vs. untreated control. No differences were observed for NDVI, proline content in leaves, or fall color retention. Overall, soil moisture variability declined in 2019, and turf quality improved in both years when any wetting agent treatment was applied, and only minor differences were observed among wetting agent treatments evaluated in this study. Other physiological indicators and soil rootzone characteristics are needed to gauge the effects of wetting agents under deficit-irrigated turfgrass. INTRODUCTIONWater scarcity, prolonged drought, and rising water costs are driving forces for turfgrass reduction or elimination in arid and semi-arid areas (Wichelns, 2010). However, turf is a multi-billion-dollar industry to the U.S. economy (Haydu, Hodges, & Hall, 2008). In the ecosystem, turfgrass brings functional, recreational, and aesthetic benefits, such as soil Abbreviations: DGCI, dark green color index; ET o , reference evapotranspiration; NDVI, normalized difference vegetation index; PGC, percent green cover; VWC, volumetric water content.

The Pacific shoot-gall nematode (Anguina pacificae Cid del Prado Vera & Maggenti, 1984) is a devastating pest on annual bluegrass (Poa annua L.) putting greens in coastal Northern California, USA. Frequently used plant protection compounds such as fenamiphos and azadirachtin are either no longer registered or very expensive and have often resulted in nematode suppression at best. A new formulation of abamectin (Divanem ® ; Syngenta, Greensboro, NC) was tested at two rates (0.15 and 0.30 kg a.i. ha −1 ) and two application frequencies (2X vs. 4X) in comparison to fluopyram (Indemnify ® ; Bayer CropScience, St. Louis, MO) applied at the rate of 0.5 kg a.i. ha −1 on three California golf courses: Pasatiempo, Santa Cruz; Laguna Seca, Monterey; and Del Monte, Monterey. Fluopyram showed the best efficacy regarding recovery from and protection against the Pacific shoot-gall disease. Generally, only two applications were required for season-long protection. Four applications of the new formulation of abamectin at the high rate were often necessary to achieve efficacy similar to fluopyram. Overall, abamectin represents another new plant protection tool that offers a treatment alternative for the management of this pathogen. Neither product had much effect on populations of soil-dwelling A. pacificae, spiral (Helicotylenchus spp.), ring (Criconemoides spp.), and root-knot (Meloidogyne spp.) nematodes.