@article{ketchum_miller_pinnix_2023, title={Stress coefficients for hybrid bermudagrass in the transition zone}, volume={9}, ISSN={["2374-3832"]}, url={https://doi.org/10.1002/cft2.20212}, DOI={10.1002/cft2.20212}, abstractNote={AbstractThe use of drought tolerant turfgrass cultivars is desirable due to greater water use efficiency and sustained acceptable turfgrass quality during times of drought stress. Crop coefficients (Kc) have traditionally been utilized to assist in reducing irrigation by comparing reference evapotranspiration (ETo) to actual evapotranspiration (ETa) of specific crops. However, Kc values are most relevant during times of nonlimiting conditions and do not quantify the amount turfgrasses restrict evapotranspiration (ET) under moderate drought stress. Stress coefficients (Ks) estimate water needs while maintaining minimally acceptable turfgrass quality. The objective of this study was to derive Ks values for four bermudagrass (Cynodon spp.) cultivars managed in the transition zone. Direct measurements of actual evapotranspiration were made through weighing lysimetry during a 2‐year field study. Experimental units were allowed to naturally dry down near wilting point and maintained at a steady level of soil moisture to calculate Ks for each cultivar. A lower Ks value indicates increased turfgrass tolerance to water stress; whereas a Ks value ≥1 suggests higher soil moisture levels are required to sustain turfgrass quality. ‘TifTuf’, ‘Latitude 36’ and ‘Tifway’ were the best performing cultivars with mean Ks values of 0.747, 0.766, and 0.796, respectively. ‘Celebration’ had the highest Ks value of 0.944. The results indicate certain bermudagrass cultivars can maintain quality with less soil water, and the reduced water requirements may be used to schedule efficient irrigation applications.}, number={1}, journal={CROP FORAGE & TURFGRASS MANAGEMENT}, author={Ketchum, Cory and Miller, Grady and Pinnix, Garland}, year={2023}, month={Jun} }
 @article{pinnix_miller_2019, title={Comparing evapotranspiration rates of tall fescue and bermudagrass in North Carolina}, volume={223}, ISSN={["1873-2283"]}, DOI={10.1016/j.agwat.2019.105725}, abstractNote={Increasing water conservation efforts across landscapes necessitate the establishment of turfgrasses that require less water to sustain functionality. Therefore, it is important to consider concurrent water use potential of popular grass species such as tall fescue (Festuca arundinacea Schreb.) and hybrid bermudagrass [Cynodon dactylon (L.) Pers. × Cynodon transvaalensis Burtt-Davy]. The primary objective of this field study was to compare water use characteristics of 'TifTuf' a recently released bermudagrass cultivar with reported drought tolerance with a commonly planted tall fescue/bluegrass mix in North Carolina. A secondary objective was to quantify minimum irrigation requirements during establishment from sod when planted during spring and summer. Direct measurements of actual evapotranspiration (ETa) were made through weighing of non-water stressed lysimeters planted with 'Triple Threat' tall fescue and TifTuf hybrid bermudagrass. Actual evapotranspiration rates during the first 14 days after planting (DAP) were 3.3 and 4.3 mm d−1 for bermudagrass and tall fescue, respectively, averaged across spring plantings. Tall fescue ETa 14 DAP was no different during summer establishment, while bermudagrass ETa increased to 4.3 mm d−1. After 14 DAP, cumulative bermudagrass ETa was 44% less than tall fescue when established in spring. Cumulative bermudagrass ETa was similar to tall fescue (3% less) following summer establishment. Both grasses provided acceptable turf quality (TQ ≥ 6), when planted during spring, unlike tall fescue which resulted in unacceptable TQ following summer establishment. Results indicate the use of TifTuf bermudagrass can provide acceptable quality in the landscape while significantly reducing turfgrass water use compared to Triple Threat tall fescue when adapted to localized conditions.}, journal={AGRICULTURAL WATER MANAGEMENT}, author={Pinnix, Garland D. and Miller, Grady L.}, year={2019}, month={Aug} }
 @article{pinnix_miller_2019, title={Crop Coefficients for Tall Fescue and Hybrid Bermudagrass in the Transition Zone}, volume={5}, ISSN={["2374-3832"]}, DOI={10.2134/cftm2019.02.0013}, abstractNote={Core Ideas The use of historical and current weather data is an economical alternative for scheduling landscape irrigation. Standard suggested crop coefficients of 0.8 (cool-season) and 0.6 (warm-season) will often result in overwatering in the transition zone. When using historical weather data to schedule landscape irrigation, locally-derived crop coefficients should be used to increase efficiency. Accurate turfgrass crop coefficients are critical when scheduling irrigation based on reference evapotranspiration (ETo). Currently, locally derived turfgrass crop coefficients are lacking in the transition zone. The objective of this field study was to derive crop coefficients (Kc) for 'Triple Threat' tall fescue (Festuca arundinacea Schreb.) and 'Tifway' hybrid bermudagrass [Cynodon dactylon (L.) Pers. × Cynodon transvaalensis Burtt-Davy] managed in the transition zone. Direct measurements of actual evapotranspiration (ETa) were made through the weighing of lysimeters planted with tall fescue and hybrid bermudagrass. Data were collected from May through October of 2017 and 2018 from nonstressed turfgrass. Turfgrass crop coefficients were computed by the quotient of ETa and ETo, calculated from the ASCE-Standardized reference evapotranspiration equation using meteorological data collected from an on-site weather station. Tall fescue and hybrid bermudagrass Kc varied by month (P < 0.0001). Means for tall fescue and hybrid bermudagrass Kc ranged from 0.69 to 0.85 (± 0.16 SD) and 0.44 to 0.59 (± 0.10 SD), respectively. Tall fescue Kc exceeded hybrid bermudagrass every month as the result of higher ETa. The use of locally-derived turfgrass crop coefficients can assist turfgrass managers in the transition zone to better meet turfgrass water demands.}, number={1}, journal={CROP FORAGE & TURFGRASS MANAGEMENT}, author={Pinnix, Garland D. and Miller, Grady L.}, year={2019}, month={Jul} }
 @article{miller_pinnix_bartley_mccauley_jackson_2019, title={Evaluation of Turfgrass Clippings from Mulching Versus Side Discharge Mower Operation}, volume={5}, ISSN={["2374-3832"]}, DOI={10.2134/cftm2019.06.0050}, abstractNote={Mower design and operation have been based on reducing clipping size to enhance filtering into the turfgrass canopy away from the surface. Reduced clippings on the surface can increase surface uniformity, a primary goal for lawn mower use. This study was conducted to determine the effectiveness of mulching mower units to reduce clipping particle size compared with traditional side-discharge mower units. Three commercially available mowers of different horsepower/ size were tested in mulching and side-discharge modes of operation to evaluate clipping parameters from tall fescue and zoysiagrass maintained under typical home-lawn conditions. Turfgrass species and mower size had a greater impact on clipping length and specific projected area than mode of operation. Tall fescue clippings were 28% longer than zoysiagrass and had a 34% greater specific projected area. A medium or large mower produced clippings 28 to 31% shorter than the small mower and decreased the specific projected area by 19 to 32%. Mulching operation did not decrease clipping size as hypothesized. Instead, mulching resulted in average increases of 9 and 0.2% in clipping length and specific projected area, respectively. A side discharge mode of operation may result in fewer clippings on the surface, increasing surface uniformity compared to a mulching mode of operation. I t has been reported that recycling lawn clippings promotes retention of plant nutrients and enhances turfgrass quality (Heckman et al., 2000; Kopp and Guillard, 2002; Bigelow et al., 2005). Little information has been found in the literature as it relates to turfgrass particle size from mowing and decomposition rates. Studies by Angers and Recous (1997) reported the decomposition of rye (Secale cereal L.) green residues and wheat (Triticum aestivum L.) straw was influenced by particle size. It seems reasonable to postulate from previous work that smaller turfgrass clippings are more likely to filter down through the turfgrass canopy to the soil surface, enhancing the onset of decomposition and providing an environmental benefit. From a consumer’s perspective, fewer clippings visible on the turfgrass surface can result in a more uniform, attractive turfgrass canopy. Rotary lawn mowers are equipped with decks that house one to three horizontal rotating blades that cut turfgrasses. The decks of these mowers are designed to lift, cut, and discharge leaf tissue through side or rear orifices. Many mowers offer a mulching Crop Forage Turfgrass Manage. 5:190050. doi:10.2134/cftm2019.06.0050 © 2019 The author(s). Re-use requires permission from the publisher. Published October 17, 2019}, number={1}, journal={CROP FORAGE & TURFGRASS MANAGEMENT}, author={Miller, Grady L. and Pinnix, Garland D. and Bartley, Paul C. and McCauley, Raymond K. and Jackson, Brian E.}, year={2019}, month={Oct} }
 @article{mccauley_pinnix_miller_2019, title={Fraise Mowing as a Spring Transition Aid}, volume={5}, ISBN={2374-3832}, DOI={10.2134/cftm2019.04.0025}, abstractNote={Core Ideas Fraise mowing can reduce perennial ryegrass cover in overseeded bermudagrass turf. More aggressive fraise mowing treatments had less ryegrass cover after treatment. June fraise mowing treatments produced a more consistent transition. Fraise mowing temporarily reduced bermudagrass cover and turf quality. Perennial ryegrass (Lolium perenne L.) often must be removed culturally or chemically from overseeded hybrid bermudagrass [Cynodon dactylon (L.) Pers. × Cynodon transvaalensis Burtt-Davy] in the spring. Fraise mowing has traditionally been used for shallow organic matter management. However, turfgrass managers are utilizing this novel cultural practice for additional uses including annual bluegrass (Poa annua L.) removal in cool-season turf. The objective of this study was to evaluate fraise mowing as a viable spring transition aid. Hybrid bermudagrass was overseeded with perennial ryegrass in the fall of 2016 and 2017. Fraise-mowing treatments were made at three depths (0.25, 0.5 and 0.75 inches) in May and June of 2017 and 2018. Perennial ryegrass-cover, bermudagrass-cover, and turfgrass quality (TQ) were assessed weekly after fraise mowing until late July each year. Intermediate and deep (0.5- and 0.75-inch) fraise mow treatments in May reduced perennial ryegrass cover compared with the untreated control. All fraise-mowing treatments performed in June resulted in decreased ryegrass cover. However, all treatments including untreated controls had no ryegrass present and ≥ 90% bermudagrass cover in late July of both years. Unacceptable TQ (<6) followed fraise mowing at all depths. Fraise-mowing depth and timing impacted the duration of unacceptable TQ. The intermediate June fraise-mowing treatment effectively removed perennial ryegrass and had unacceptable TQ for the shortest duration after treatment. Fraise mowing at 0.5- or 0.75-inch depths provides turf managers with an effective cultural practice for removing perennial ryegrass from overseeded bermudagrass.}, number={1}, journal={CROP FORAGE & TURFGRASS MANAGEMENT}, author={McCauley, Raymond K. and Pinnix, Garland D. and Miller, Grady L.}, year={2019} }
 @article{pinnix_mccauley_miller_2019, title={Leaf Wetness Influences Turf Colorant Application}, volume={5}, ISSN={["2374-3832"]}, DOI={10.2134/cftm2018.12.0099}, abstractNote={Core Ideas Conditions during application can impact the visual quality of turf colorants. The response of measured colorant color parameters to pre-application irrigation was variable among products tested. Turf colorants with increased product viscosity benefit from pre-application irrigation. Turf colorants are primarily used on warm-season grasses throughout the southern United States to maintain aesthetic quality leading into and during winter dormancy. To maximize aesthetic quality, turf colorants must be applied when certain conditions are present. The objective of this field study was to evaluate the presence of leaf moisture during turf colorant application to dormant turfgrass and its effect on measured color parameters (color, intensity, and hue angle). Four turf colorants were applied to wet and dry (i.e., irrigated and non-irrigated) dormant ‘Tifsport’ hybrid bermudagrass [Cynodon dactylon (L.) Pers. × Cynodon transvaalensis Burtt-Davy] and ‘El Toro’ zoysiagrass (Zoysia japonica Steud.). Color parameters were evaluated weekly for 5 consecutive weeks following turf colorant application. Average colorant color and intensity ratings were 14 and 10% higher when dormant turfgrass was irrigated prior to colorant application, respectively. Color and intensity ratings were unaffected by leaf wetness following applications of Endurant Premium and Green Turf Paint applications. However, color and intensity ratings increased by 38 and 26%, respectively, when turfgrass was irrigated prior to the application of Green Lawnger and Ultradwarf Super. Negative effects (i.e., streaking) commonly seen during application of turf colorants higher in viscosity were alleviated as a result of pre-application irrigation. Hue angles quantified from digital images were unaffected by the presence of leaf wetness during colorant application. Results from this research indicate turfgrass managers should consider wetting dormant turfgrass through a quick irrigation cycle to mitigate possible unattractive streaking that result from the use of higher-viscosity products or increased application rates.}, number={1}, journal={CROP FORAGE & TURFGRASS MANAGEMENT}, author={Pinnix, Garland D. and McCauley, Raymond K. and Miller, Grady L.}, year={2019}, month={Mar} }
 @article{pinnix_mccauley_miller_2018, title={Air Temperature Effects on Turfgrass Colorant Transfer}, volume={4}, ISSN={["2374-3832"]}, DOI={10.2134/cftm2017.12.0091}, abstractNote={Core Ideas
Air temperature during turf colorant application can greatly affect colorant performance.
Turf colorant applications that occur in colder temperatures increases the risk of colorant transfer onto absorbent materials.
Turf colorant selection is imperative as certain products are able to adhere to the turfgrass canopy better than others.
Turf colorants are used to provide green color to turfgrasses during times of stress and dormancy. When used to treat dormant turfgrass, proper application timing is imperative to increase functionality. The objective of this field study was to evaluate effects of air temperature on colorant transfer onto an absorbent material. Seven turfgrass colorants were applied to dormant ‘Tifway’ hybrid bermudagrass [Cynodon dactylon (L.) Pers. × Cynodon transvaalensis Burtt‐Davy] and ‘El Toro’ zoysiagrass (Zoysia japonica Steud.) at three air temperatures (25, 45, and 60°F). Colorant transfer for each air temperature treatment was sampled at 1, 2, 4, and 7 days after application (DAA) by dragging an absorbent cloth the length of treated turfgrass plots. When applied at 25°F, colorant transfer was 2.2 and 2.3 times greater than the amount transferred at 45 and 60°F, respectively. Regreen, Fairway, Perennial Ryegrass, and Premium all exceeded the threshold for colorant transfer (0.030 reflectance) 7 DAA when applied at 25°F. Spaint was the only product to have an acceptable measure of colorant transfer across air temperatures. Additionally, Regreen did not have an acceptable level of colorant transfer at any point during evaluations. When applied at 45 and 60°F, colorant transfer for Spaint, Green Turf Paint, and Green Dye Turf were at least 5 and 6 times lower, respectively, compared to other colorants. Data implied increased potential for colorant transfer when applied at 25°F compared to 45 or 60°F and illustrate variability in product transfer potential.}, number={1}, journal={CROP FORAGE & TURFGRASS MANAGEMENT}, author={Pinnix, Garland D. and McCauley, Raymond K. and Miller, Grady L.}, year={2018}, month={Jun} }
 @article{pinnix_miller_bowman_grabow_2018, title={Color, Transfer, and Application Parameters of Turfgrass Colorants}, volume={110}, ISSN={["1435-0645"]}, DOI={10.2134/agronj2017.03.0164}, abstractNote={Core Ideas
Turf colorants can be used as an alternative to winter overseeding, therefore saving turf managers resources.Multidimensional scaling analysis can be used to separate turf colorants into groups, allowing turf managers to better select products based on color parameters.Turf colorant transfer varies greatly among products and can result in severe staining.
Turfgrass colorants are primarily used as an alternative to winter overseeding. Information on colorants is limited in the scientific literature. The primary objective of this field study was to evaluate the effect turfgrass colorants had on color parameters (colorant intensity, color, and hue angle) of dormant bermudagrass (Cynodon sp.). Secondary objectives were to examine colorant transfer (wipe off) from the turfgrass surface to an absorbent material and to measure product viscosities. Twenty‐five colorants were applied at two spray volumes (75 and 112 mL m–2) on dormant bermudagrass at two heights of cut (0.3 and 1.5 cm). Multidimensional scaling and cluster analysis were used to separate colorants based on measured color parameters. Group 1 colorants maintained colorant intensity the longest, but colorant color was reduced at application due to the appearance of bright blue (e.g., Munsell 5BG/6/6) and bright green (e.g., Munsell 7.5GY/7/10) colors. Group 2 colorants provided the darkest green (e.g., Munsell 5GY/4/4) color, while Group 3 colorants provided minimal color change of dormant turfgrass. Among the Group 2 colorants, Green Lawnger, Lesco Green, Ultradwarf Super, Southwest Green, and Endurant provided a natural green color. Measurements of colorant transfer showed that Blue, Regreen, SprayMax, Green Dye Turf, Titan Green Turf, Solarogen, and Endurant have the highest propensity to disassociate from treated turfgrass. The use of multidimensional scaling and cluster analysis provided new information regarding a number of turf colorants. Grouping products by measured parameters indicated that products within Group 2 provided superior performance.}, number={1}, journal={AGRONOMY JOURNAL}, author={Pinnix, Garland D. and Miller, Grady L. and Bowman, Daniel C. and Grabow, Garry L.}, year={2018}, pages={66–76} }
 @article{zhang_pinnix_zhang_miller_rufty_2017, title={Evaluation of Key Methodology for Digital Image Analysis of Turfgrass Color Using Open-Source Software}, volume={57}, ISSN={["1435-0653"]}, DOI={10.2135/cropsci2016.04.0285}, abstractNote={Digital image analysis is a frequently used research technique to provide an objective measure of turfgrass color, in addition to the traditional visual rating. A commonly used method relies on commercial software package SigmaScan Pro to quantify mean hue angle, saturation, and brightness values from turf images, and to calculate a dark green color index as the measure of color. To enable turf image analysis to function on an open‐source platform, a method was developed within ImageJ to batch process turf images for color parameters. This Java‐based ImageJ plugin quantifies hue angle, saturation, and brightness values and calculates a dark green color index. In addition, information on the variability of these color parameters can be simultaneously acquired. This new method was used to quantify color parameters of turf images collected from field plots of tall fescue (Schedonorus arundinacea Shreb. Dumort.), Kentucky bluegrass (Poa pratensis L.), ryegrass (Lolium ssp.), hybrid bermudagrass (Cynodon dactylon (L.) Pers. × C. transvaalensis Burtt‐Davy), and creeping bentgrass (Agrostis stolonifera L.). While color parameter values differed little between ImageJ and SigmaScan, the time saved in processing images using ImageJ was considerable. Aside from software, analysis of color parameters acquired from the five turfgrass species indicated that hue angle alone can adequately measure turf color in digital images. Results also demonstrated that, in addition to light source, camera settings should remain fixed during photo capture to avoid introducing errors. The ImageJ plug‐in developed in this study is made available at www.turffiles.ncsu.edu.}, number={2}, journal={CROP SCIENCE}, author={Zhang, Chenxi and Pinnix, Garland D. and Zhang, Zheng and Miller, Grady L. and Rufty, Thomas W.}, year={2017}, pages={550–558} }