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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08.14 GOLF COURSE MANAGEMENT 87 a randomized complete block design and were 6.5 feet × 10 feet (2 meters × 3 meters) in size with treatments replicated four times. Research sites were maintained to normal putting green standards with daily mowing heights of 0.125 inch (3.2 millimeters), irriga - tion applied as needed to prevent wilt, fertil- ization with 6 pounds nitrogen/1,000 square feet (29 grams nitrogen/square meter) yearly and treatment with fungicides as needed to minimize disease pressure. Visual quality and normalized differential vegetative index (NDVI), an electronic mea - surement of "green" tissue, were assessed twice weekly. Daily measurements included canopy temperature using a handheld infrared ther - mometer, chlorophyll content with a handheld chlorophyll meter, and soil moisture using an electronic probe, with all measurements tak - ing place one hour after solar noon. Carbon dioxide exchange ratios were measured twice weekly using a CIRAS-II Portable Photosyn - thesis System as well as photosynthesis (light effciency or fuorescence) with a FluorPen FP 100. Carbon dioxide exchange rate measures the net CO 2 exchange between the surface of the turfgrass and the atmosphere. A positive measurement indicates respiration exceeds photosynthesis, whereas a negative measure - ment results if photosynthesis exceeds respira- tion. Root weight as well as soil and tissue nu- trient analyses were conducted at the initiation and completion of the studies. Growt amber studies In addition to feld trials, growth cham - ber studies were conducted to evaluate treat- ments in a controlled, stressful environment. Plugs 4 inches (10.16 centimeters) in diameter and 4 inches deep were removed from research greens and placed in 6-inch (15.24-centime - ter) diameter × 12-inch (30.48-centimeter) deep pots flled with an 85:15 sand/peat root- zone mix. Plugs were established to fll pots and were placed in growth chambers at tem - peratures stressful for turfgrasses — higher (95 F [35 C]) temperatures for bentgrass and colder (23 F [-5 C]) temperatures for bermu - dagrass. In addition, an unstressed, untreated control remained in a normal greenhouse en - vironment. All pots received 3.4 ounces (100 milliliters) of tap water every three days. Car - bon dioxide exchange ratios and fuorescence measurements were taken every other day for the duration of these studies. Lig t transmitted to t e turf To determine product effects on the quan - tity and quality of light reaching the turfgrass canopy, products were applied to transparent acrylic sheets 10 × 8 inches (25 × 20 centime - ters) using a spray chamber calibrated at 20 gallons/acre (187 liters/hectare) to deliver the application rates listed in Table 1. Once dried, acrylic sheets were individually placed on the surface of a custom-made cardboard box 7.87 × 9.44 × 9.84 inches (20 × 24 × 25 centime - ters) tape-sealed to block all light except that transmitted through the acrylic sheet. Pho - tosynthetic active radiation intensity (μmol/ square centimeter/second of transmitted light integrated between 400 and 700 nanometers) and spectral distribution (~400 to 1,100 nano - meters) of transmitted light was measured with an LI-1800 Portable Spectroradiometer. Measurements were taken outdoors on cloud- free days at solar noon, which ranged from 1300 to 1400 hours during summer months. Measurements were repeated on four sepa - rate days. Leaf penetration In an auxiliary study, PAR and Turf Screen were investigated to ascertain whether or not products penetrated treated leaves or remained on the leaf surface. Both products were diluted to respective feld solutions and applied evenly to grass blades with the tracer dye, isothiocyanate. Treated plants remained in the greenhouse for 48 hours before being clipped then imaged using a Confocal Imag - ing System at 20× magnifcation with data used to create 3-D renderings of the leaf. Results Canopy temperature Turf color response following applica - tion of various products is shown in Figure 1. When evaluating canopy temperatures fol - lowing application, in most instances, tested products did not lower canopy temperatures compared to the untreated control (Table Product/company Rate † Turf Screen/Turf Max ‡ 2.5 ounces/1,000 square feet (7.97 liters/hectare) PAR/Harrell's LLC ‡ 0.37 ounce/1,000 square feet (1.17 liters/hectare) Title Phyte (derivative of potassium phosphite) (0-0-30)/Harrell's LLC 4 ounces/1,000 square feet (12.572 liters/hectare) Turf Screen + TitlePhyte 2.5 ounces/1,000 square feet (7.97 liters/hectare) + 4 ounces/1,000 square feet (12.572 liters/hectare) PAR + TitlePhyte 0.37 ounce/1,000 square feet (1.17 liters/hectare) + 4 ounces/1,000 square feet (12.572 liters/hectare) Chipco Signature (fosetyl-aluminum + Stressgard)/Bayer ‡ 6 ounces/1,000 square feet (19.128 liters/hectare) Fosetyl-Al (fosetyl-aluminum)/Quali-Pro ‡ 4 ounces/1,000 square feet (12.572 liters/hectare) Civitas Harmonizer (proprietary pigment)/ Petro-Canada Lubricants ‡ 0.023 ounce/1,000 square feet (0.073 liter/hectare) Civitas (mineral oil) + Harmonizer/Petro-Canada Lubricants ‡ 0.367 ounce/1,000 square feet (1.17 liters/hectare) + 0.023 ounce/1,000 square feet (0.073 liter/hectare) † Applications were made every 14 days. ‡ Applications received a potassium supplement using Stress Relefe (0-0-25) (Harrell's LLC) at 4 ounces/1,000 square feet (12.6 liters/hectare). Table 2. Products and rates for 2013 and 2014 greenhouse and growth chamber trials to reduce summer stress of creeping bentgrass and improve winter survival of hybrid bermudagrass. 2013 and 2014 greenhouse and growth chamber trials

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