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GREEN LIGHT ON GOLF Managing Summer Decline in a Creeping Bentgrass Green By Peter H. Dernoeden, Ph.D., and C. P. Ryan, Dept. of Plant Science and Landscape Architecture, University of Maryland Previous studies have documented improved summer performance of creeping bentgrass (Agrostis stolonifera) putting greens treated with selected fungicides even in the absence of disease. Chipco Signature, especially when tank-mixed with either Daconil or Fore Rainshield, has been associated with color enhancement and improved cover and quality. Mancozeb was shown to mitigate scalping in “puffy” putting green turf in summer (Dernoeden and Fu, 2008). Other studies have demonstrated the superior ability of spoonfeeding with urea to improve summer quality of putting greens, when compared to biostimulants, chelated iron and micronutrient products (Settle and Dernoeden, 2009). The non-disease-related benefits provided by some fungicides and urea are said to reduce summer decline. Summer decline of creeping bentgrass greens normally occurs in response to high-temperature stress combined with mechanical injury and sometimes diseases. Additional information regarding summer decline management with other products is warranted. The objective of this study was to assess various fungicides, as well as Super Stimulant (organic peat humates; 6% humic acid) and Nano Argentum (elemental silver in osmotized water applied at 41 ml/acre), applied alone and/or tank-mixed with another compound, for their ability to improve the summer quality of a creeping bentgrass putting green turf. Urea was applied in a spoonfeeding program and served as the standard for comparison. Our research methods This field study at the University of Maryland Paint Branch Turfgrass Research Facility in College Park was conducted on an 80/20 sand/ sphagnum peat moss (v/v) creeping bentgrass putting green constructed to USGA specifications. The area was a mature stand of ‘Declaration’ creeping bentgrass. The study area was fertilized with 2.5 lbs. N/1,000 ft 2 from mostly 20-20-20 between September 20 and November 11, 2009. The bentgrass received an additional 0.5 lb. N/1,000 ft 2 from 20-20-20 in April and May 2010. Thereafter, the study area received no additional nitrogen, except for that provided by the urea spoonfeeding treatment. The turf was mowed five times weekly to a height of 0.150 inches and otherwise was maintained as a putting green. To induce mechanical stress, lower mowing heights were imposed on three dates in July, as described below. During the study period, daytime high temperatures generally exceeded 90ºF, and nighttime temperatures seldom fell below 68ºF. The site was irrigated to prevent drought stress and was syringed as needed. Treatments were applied three times on a two-week interval on June 15, June 29 and July 13, 2010. Turfgrass quality was rated visually on a 0 to 10 scale, where 0 = brown or dead 26 MTC TURF NEWS
turf, 8.0 = minimal acceptable quality for a creeping bentgrass putting green, and 10 = optimum greenness, uniformity and density. Color was rated visually on a 0 to 10 scale, where 0 = brown or dead turf, 8 = minimum acceptable color, and 10 = dark green turf. Yellow spot became pronounced the week of July 24 (the cause was unknown, but blue-green algae have been implicated) and was evaluated by counting the number of spots in each plot. Rings caused by Rhizoctonia zeae were counted, and blighting by R. solani was visually assessed on a 0 to 100 scale. The entire site was treated with Insignia (0.9 oz./1,000 ft 2 ) to control the Rhizoctonia diseases on June 29. Our results — summer quality Treatments were initiated on June 15, 2010. As noted previously, the site was treated with Insignia, which effectively controlled the Rhizoctonia diseases present in June. Hence, these quality ratings reflect color and uniformity and generally were not impacted by disease. Any residual disease in plots was disregarded in the quality ratings. During the period between June 23 and July 12, the study area was mown to a height of 0.150 inches. Unlike in previous years, the Declaration did not become “puffy,” and there was little mechanical stress during this period. At this time of minimal stress, Fore Rainshield and Signature + Fore Rainshield improved quality compared to the control on all three rating dates (see Table 1). Urea, Chipco Signature alone and Super Stimulant + urea showed improved quality compared to the control by July 12 (i.e., 13 days following the second application of treatments). On July 16, the mowing height was reduced to 0.135 inches and then to 0.125 inches on July 19 and July 20. Plots were double cut on July 19 and July 20, at which time daily air temperatures were in excess of 95ºF. Table 1. Color and quality of a ‘Declaration’ creeping bentgrass green in summer decline, 2010. Rate Overall quality ++ Color Fungicide + (Product/1,000 ft 2 ) June 23 June 29 July 12 July 20 July 26 July 12 Chipco Signature 80WG 4.0 oz. 7.9 ab ‡ 6.8 bcd 8.0 bc 6.7 b 5.8 d 7.9 de Fore Rainshield 80WP 6.0 oz. 8.7 a 7.8 ab 8.4 ab 7.9 a 7.3 bc 8.2 cd Torque 3.6SC 0.6 oz. 7.4 b 7.4 abc 7.7 cd 6.2 bc 6.4 d 7.5 ef Urea 46-0-0 0.15 lb. N 8.0 ab 7.1 a-d 8.8 a 8.3 a 8.1 a 8.7 ab Super Stimulant 6.0 fl. oz. 7.2 b 6.6 cd 7.5 d 5.9 c 5.6 d 7.4 ef Signature + Fore 4.0 + 6.0 oz. 8.6 a 7.7 ab 8.6 a 7.7 a 7.3 c 8.4 bc Signature + Torque 4.0 + 3.2 oz. 8.1 ab 8.0 a 7.9 bcd 6.5 bc 5.9 d 7.7 ef Super Stimulant + Urea 6.0 oz. + 0.15 lb. N 8.1 ab 7.4 abc 8.7 a 6.5 bc 8.1 ab 8.8 a Nano Argentum 0.032 oz. 7.3 b 6.1 d 7.6 cd 5.9 c 5.8 d 7.7 ef Untreated — 7.2 b 6.7 cd 7.5 d 5.9 c 5.7 d 7.5 ef ++ Treatments were applied on June 15, June 29 and July 13, 2010. ++ Plots were mowed to a height of 0.150 inches; mowing height was reduced to 0.135 inches on July 16 and to 0.125 inches on July 19 and July 20, and increased to 0.150 inches on July 22 and thereafter. ‡ Means in a column followed by the same letter are not significantly different according to Fisher’s LSD, 5%. SUMMER 2011 27
Page 1: MANAGING SUMMER DECLINE in Creeping
Page 5 and 6: MARYLAND TURFGRASS COUNCIL 12 Press
Page 7 and 8: December 1st and March 1st. We were
Page 9 and 10: stocks on golf courses after Decemb
Page 11 and 12: continued • TURF TALK 27, June 11
Page 13 and 14: Fusilade II may be a viable alterna
Page 16 and 17: APPLIED RESEARCH 16 MTC TURF NEWS
Page 18 and 19: APPLIED RESEARCH • continued Fert
Page 20: APPLIED RESEARCH • continued cont
Page 23 and 24: to 9.4) on May 13 (Table 1). Echelo
Page 25: MTC Membership Application ________
Page 30: TURF INDUSTRY CALENDAR OF EVENTS IN

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