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2010 Turf Screen Turf Quality, Etc.

Use of Turf Screen and Fungicide Tank-mixtures
for Turfgrass Quality and Dollar Spot Control, 2010

Turfgrass Disease Solutions, LLC
Steven McDonald, M.S. and Rick Grala

The purpose of the trial was to further evaluate Turf Screen with and with two commonly used fungicides (Banner MAXX and Daconil Ultrex) for dollar spot suppression and control, and turfgrass quality. This trial was conducted on the driving range at Bellewood Golf Club located in Pottstown, PA. Plots were 5 x 5 ft and replicated 3 times in the a randomized complete block design. The turfgrass should be considered lean with only 0.5 lb N/M applied this season as a granular with Dimension. Turfgrass was irrigated as needed to prevent drought stress and mown 2 times weekly.

Treatments were applied on 14 and 28 May, 11 and 25 June 2010. The Field Scout TCM 500 “NDVI” Turf Color Meter measures reflected light from turf grass in the red (660 nm) and near infrared (850 nm -NIR) spectral bands. Five individual measurements were taken per plot and averaged for analysis. The NDVI value ranges from 0.0 to 1.0 and is calculated as NDVI=(NIR-Red)/(NIR + Red). Therefore, the higher the value, the more green vegetation is present. The NDVI data are shown in table 1. Percent blue color was rated on a 0 to 100 scale where 0= no blue color and 100= entire plot coverage in dark blue color. 50%= dark sky blue color and 100= dark navy blue color. Turfgrass quality was rated on 0 to 10 scale where 7= acceptable threshold and 10= optimal quality. Percent plot area blighted by dollar spot was visually assessed on a 0 to 100 percent scale where 0= no disease and 100= entire plot area blighted. No other disease or insect pest were observed in the trial area. All data were included in the statistical analysis. Data were subjected to ANOVA using ARM Tukey Test.

Treatments were applied on 14 and 28 May, 11 and 25 June 2010. The turf color meter was used on 6 occasions to measure color. Although there was visual color differences in the plots that was mostly bluish, the color meter failed to determine these differences.

In table 2, % blue color data are shown. These visual ratings were taken at four critical parts of the trial. Following the first applied all plots receiving Turf Screen had a much bluer color when compared to plots treated with Daconil Ultrex, Banner MAXX and the untreated control. The highest level of blue was observed in plots treated with Turf Screen alone at 3.4 fl oz/M, hen was higher than the 1.7 fl oz/M rate. Following the fourth application of the materials, the color persisted for greater than 30 days (July 30). On that rating date, the highest blue color rating was observed in plots treated with Turf Screen + Daconil Ultrex following by Turf Screen alone at 3.4 fl oz/M. On the aforementioned date, all plots receiving Turf Screen either alone or in a tank mixture had significantly higher blue color when compared to plots treated with Daconil Ultrex, Banner MAXX and the untreated control.

Quality ratings are shown in table 3. It is important to note that the acceptable threshold for quality is 7.0. When the trial was started and three days following the first application, there was few distinct differences in quality. By 28 May, however, all treated plots had better quality than the untreated control and all plots receiving Turf Screen had better quality than Daconil Ultrex and Banner MAXX-alone. This trend continued for the duration of the trial. In the later part of the trial the largest factor affecting quality was dollar spot severity, however, it is important to closely examine this trend. For example, lets take a better look at treatments 3 (Daconil Ultrex-alone) and 4 (Turf Screen+ Daconil Ultrex) on 25 June. Both treatments had similar levels of dollar spot blighting, however, plots treated with the tank mixture had better quality, when compared to the single fungicide. There is a similar trend with Banner MAXX. Therefore, there was select rating dates, in which the addition of Turf Screen to the fungicide application significantly increased turfgrass quality. Field notes from the trial mentioned that creeping bentgrass in the Turf Screen treated plots increased turfgrass density and leaf blade appearance (width).

Dollar spot data are shown in table 4. Dollar spot pressure was consistent and quite high through July when it slowed significantly. On every rating date, except for 13 and 30 July, both Turf Screen-alone treatments had similar levels of dollar spot as the untreated control. There was no dollar spot observed in the fungicide-alone and fungicide + Turf Screen treated plots until 25 June. Treatments were last applied on 25 June to allow and separation in the residual control to be observed. There was no significant differences observed in the level of dollar spot control when comparing each fungicide-alone to fungicide + Turf Screen. These data indicate that there is no antagonist effects from mixing Turf Screen with either Daconil Ultrex or Banner MAXX.

Suggestions for Future Research:
Future trials should investigate the impacts of Turf Screen on curative algae control. It would also be important to tank mix it with paclobutrazol and trinexapac-ethyl to see residual in color and density response. It is important to note that the blue color may be objectionable to some and different variants of the material should be evaluated to determine the best possible combinations of pigments.

Table 1. NDVI Measurements

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