Golf Course Management

AUG 2014

Golf Course Management magazine is dedicated to advancing the golf course superintendent profession and helping GCSAA members achieve career success.

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Page 93 of 126

08.14 GOLF COURSE MANAGEMENT 89 similar to the untreated control in both stud- ies (Table 3). Turf treated with paint had lower quality over the course of the summer in both studies, with averages of 5.1 and 4.4 compared to 7.0 and 6.2 for the untreated control. Dif - ferences were observed between the two stud- ies. Study 1 had higher initial turf quality, resulting in turf quality treatment averages of 7.0 for the untreated control, 7.0 for Turf Screen, 6.9 for PAR and 7.1 for Foursome. In study 2, turf quality averages were 6.2 for the untreated control, 6.5 for Turf Screen, 6.0 for PAR and 6.1 for Foursome. The untreated control had a signifcantly higher NDVI (natural "green" color) than PAR, Turf Screen and the commercial paint throughout the summer. Differences were not observed among Turf Screen, PAR and Four - some in either study. The paint always pro- duced signifcantly lower values, with an aver- age ratio of 0.65 compared to the untreated control at 0.74. In study 2, NDVI values were similar for the untreated control, Turf Screen and PAR treatments. Carbon dioxide ex ange rate In study two, the CO 2 exchange rate (-0.059 μmol CO 2 /square centimeter/second) was lower in untreated turf than in all treated turf, indicating treatments reduced net photo - synthesis (Table 3). In both studies, the com- mercial paint had the highest CO 2 exchange rate (0.323 and 0.216 μmol CO 2 /square centimeter/second). Turf Screen and PAR performed similarly in both studies (0.182 and 0.118 μmol CO 2 /square centimeter/sec- ond in study 1, 0.090 and 0.091 μmol CO 2 / square centimeters/second in study 2). Dur - ing July when temperatures were highest, the untreated control exhibited signifcantly lower CO 2 exchange rate values (0.151) than PAR (0.341), Turf Screen (0.327) and the paint (0.477) in study 1 and signifcantly lower CO 2 exchange rate values (0.044 μmol CO 2 /square centimeter/second) than all other treatments in study 2. Growth chamber experiments did not consistently show statistical differences among untreated and treated pots, indicating treatments did not improve or lessen turfgrass tolerance to environmental stresses. Fluorescence Differences were not detected between un - treated and treated plots during study 1(Table 3). All treatments in study 2 exhibited a gen - eral increase in photosynthetic effciency, with Turf Screen exhibiting a signifcantly better rate. Inconsistency among treatments shows that none of the pigmented products provided any type of consistent relief during the heat of summer. Similar observations were made in the growth chamber studies with only the un - stressed control having a signifcantly greater photosynthetic effciency. Soil and tissue analysis Tissue and soil analyses were conducted because of the metallic (zinc and copper) con - tents of the products and their potential toxic- ity to plants (Table 3). In both studies, Turf Screen treatments were signifcantly higher in zinc concentration than all other treatments, with an average 911 ppm compared to 88 ppm for the untreated control. In regard to tissue copper concentrations, the paint was consis - tently higher with an average of 155 ppm com- pared to the other treatments, which averaged 61 ppm. After repeated applications, only the Turf Screen treatment exhibited higher zinc con - centrations in soil than the other products. However, concentrations were not believed to exceed levels that would be considered toxic to plants. Root wei No effect of treatments on root weights occurred at the end of feld studies (data not shown). Lig t quality and microscopy imaging With little positive infuence on reducing temperatures and increasing CO 2 exchange rates, additional research was performed on product effects on light quality and leaf pene - tration. Spectroradiometer data indicated a re- duction in photosynthetically active radiation (μmol/square centimeter/second integrated from 400 to 700 nanometers) when products were applied to transparent acrylic sheets (Fig - ure 2). The copper-based pigments Foursome and PAR reduced photosynthetic active radia - tion transmission by 19% and 21%, respec- tively. Even greater reductions were observed with Turf Screen (39%) and the commercial paint (46%). In an attempt to better understand how well products penetrate treated leaves, micro - scopic imaging was performed. The interac- tion between applied products and leaf blades indicated Turf Screen remained mostly on the plant surface (Figure 3), and in some cases covered stomata, whereas PAR actually en - Wavelength intensities Figure 2. Spectroradiometer data indicating wavelength intensities following applications of various pigments and paint to transparent acrylic sheets. 16000 14000 12000 10000 8000 6000 4000 2000 0 300 400 500 600 700 800 900 1000 1100 Intensity (µmol/square centimeters/second) Wavelengths Control Turf Screen PAR Foursome Paint

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