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.

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. AbstractPerennial 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.

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 http://www.turffiles.ncsu.edu.

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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.