Author : Charles J. Schmid
Publisher :
ISBN 13 :
Total Pages : 274 pages
Book Rating : 4.:/5 (975 download)
Book Synopsis Influence of Nutrient Management and Soil PH on Anthracnose Severity of Annual Bluegrass Putting Green Turf by : Charles J. Schmid
Download or read book Influence of Nutrient Management and Soil PH on Anthracnose Severity of Annual Bluegrass Putting Green Turf written by Charles J. Schmid and published by . This book was released on 2016 with total page 274 pages. Available in PDF, EPUB and Kindle. Book excerpt: Anthracnose (Colletotrichum cereale Manns sensu lato Crouch, Clarke, and Hillman) is a fungal disease of annual bluegrass [Poa annua L. f. reptans (Hausskn) T. Koyama; ABG] turf, which can be intensified when abiotic conditions weaken turfgrass plants. Five field trials conducted from 2009 to 2015 evaluated the effects of N program, soluble N rate, N source, K source and rate, and soil pH on anthracnose severity of ABG maintained as putting green turf. Soluble N rate applied during midseason had the greatest influence on anthracnose severity. Granular N rate and season in which the majority of granular N was applied also influenced disease severity but to a lesser extent. Soluble N applied at 73 kg N ha-1 yr-1 in combination with moderate rates (147 or 220 kg N ha-1 yr-1) of granular N applied during the spring resulted in the greatest reduction in disease severity. Further analysis of the influence of soluble N rate on anthracnose severity found that higher rates (14.6 to 24.4 kg N ha-1 wk-1) of soluble N can be applied from late-spring through early-summer to reduce disease severity, but as the summer progresses moderate (9.8 kg N ha-1 wk-1) to low (4.9 kg N ha-1 wk-1) rates of soluble N should be applied to avoid excessive rates of N increasing disease severity. Playability (i.e. ball roll distance) of ABG turf was reduced by rates of soluble N applied at e"14.6 kg ha-1 wk-1 compared to N applied at 4.9 kg ha-1 wk-1 . Basic N sources (potassium nitrate and calcium nitrate) applied at 4.9 kg N ha-1 every 7-d reduced disease severity compared acidic N sources (ammonium nitrate and ammonium sulfate) applied at the same rate and frequency; however, when N was applied at 4.9 kg ha-1 every 14-d, disease severity was greater and few differences were seen among N sources. Potassium (K) fertilization reduced anthracnose severity regardless of K rate or K source. Critical soil K and leaf K concentration values affecting anthracnose severity were calculated to range from 43 to 70 mg kg-1 (Mehlich 3) and 19.3 to 23.1 g kg-1, respectively, using nonlinear regression models (Cate-Nelson, linear plateau, and quadratic plateau). Plots with moderately acidic soil (pH