Golf Course Management

DEC 2017

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

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12.17 GOLF COURSE MANAGEMENT 65 Effects of N and FeSO 4 on Microdochium patch 6 inches (15.24 cm) of USGA-recommended- particle-size sand directly on a naturally slop - ing native soil area in April 2013. Annual blue- grass was established using aerification cores from Corvallis (Ore.) Country Club. The green was grown in using a compound fertilizer with micronutrients (Andersons 28- 5-18). A total of 3.8 pounds nitrogen/1,000 square feet (18.57 grams/square meter) was ap - plied from April to July. In August, 0.2 pound nitrogen/1,000 square feet (0.98 gram/square meter) was applied every two weeks using the same fertilizer, and in September, 0.2 pound nitrogen/1,000 square feet was applied every two weeks using urea. In between trial years, a total of 1.6 pounds nitrogen/1,000 square feet (7.82 grams/square meter) was applied using the Andersons fertilizer. Mowing height was set at 0.15 inch (3.81 mm). Over the summer, aerification and top - dressing were carried out, and fungicides were applied to control dollar spot and anthracnose. No fungicides were applied during the trial dates from September through April. The experimental design consisted of a ran - domized complete block design with a 5 × 3 factorial arrangement that included five rates of iron sulfate heptahydrate (0, 0.25, 0.5, 1.0 and 2.0 pounds iron sulfate/1,000 square feet; 0, 1.22, 2.44, 4.88 and 9.76 grams/square meter) and three rates of nitrogen applied as urea (0, 0.1 and 0.2 pound nitrogen/1,000 square feet; 0, 0.49 and 0.98 gram/square meter). Applications were made every two weeks from Sept. 26, 2013 to April 15, 2014, and re - peated from Sept. 22, 2014 to April 15, 2015. All treatments were applied using a CO 2 -pres- surized backpack sprayer with a pressure of 40 psi (280 kpa) and a carrier volume of 2 gallons water/1,000 square feet (814 liters/hectare). To assess whether the treatments would in - fluence wear tolerance, golfer traffic represent- ing 76 golf rounds per day was replicated by walking on the plots with golf shoes five days a week, following the protocol of Hathaway and Nikolai (4). Response variables included percent disease, turfgrass quality and fertil - ity analyses. Results and discussion Urea In the first year, urea applications did not increase the incidence of Microdochium patch when applied in combination with low rates of iron sulfate (Figure 1). Urea applications led to greater Microdochium patch incidence only when they were applied in conjunction with 1 or 2 pounds iron sulfate/1,000 square feet. The only instance in which no nitrogen led to a lower incidence of Microdochium patch com - pared with a rate of 0.1 pound nitrogen/1,000 square feet was at the 1 pound iron sulfate level. In the second year of the study, application of nitrogen at 0.1 pound/1,000 square feet did not increase Microdochium patch compared with plots not receiving any nitrogen (Table 1). These two years of data strongly suggest that applying 0.1 pound nitrogen/1,000 square feet every two weeks in the form of urea does not lead to a greater incidence of Microdochium patch than applying no nitrogen. Iron sulfate For iron sulfate applications in the first year, the lowest level of Microdochium patch was observed when 2 pounds iron sulfate/1,000 square feet was applied every two weeks in the absence of urea followed by 2 pounds of iron sulfate in combination with 0.1 pound nitro - gen/1,000 square feet or 1 pound of iron sul- fate in the absence of urea (Figure 1). In year two, all iron sulfate applications (0.25, 0.5, 1.0 and 2.0 pounds/1,000 square feet) resulted in less Microdochium patch when compared with no iron sulfate applica - tions (Table 1), with disease incidence decreas- ing as the rate of iron sulfate increased. This two-year study strongly suggests that iron sul - fate applications reduce the incidence of Mi- crodochium patch on annual bluegrass put- ting greens. Rate/1,000 square feet × 2 weeks % disease † 0.0 pound nitrogen (N) 17 b 0.1 pound nitrogen 14 b 0.2 pound nitrogen 26 a 0.0 pound iron sulfate (FeSO 4 ) 43 a 0.25 pound iron sulfate 23 b 0.5 pound iron sulfate 16 bc 1.0 pound iron sulfate 10 c 2.0 pounds iron sulfate 3 d † Within columns, means followed by the same letter are not significantly different. Table 1. Effects of nitrogen and iron sulfate applications on the incidence of Microdochium patch, as measured by percent disease on an annual bluegrass putting green in Corvallis, Ore., on Feb. 16, 2015.

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