243-3 Potassium Fertilization Increases Microdochium Patch Incidence and Severity on Creeping Bentgrass.
This project was initiated in 2011 on a USGA putting green with ‘A4’ creeping bentgrass. The experiment was a randomized complete block design with four replications. The treatments included five different levels of biweekly liquid potassium sulfate at rates ranging from zero to 30 kg/ha of K. Paired soil and plant tissue samples were collected monthly along with measurements of clipping yield. Turfgrass color and visual quality was evaluated biweekly. Disease incidence was quantified by counting Microdochium patch infection centers and disease severity was visually rated as percent area affected by using the grid intersection method.
Few, if any, differences in turf color, quality, or growth rate among the treatments were observed during the first four years of the study. In the fifth year, significantly lower turf quality was observed on the two no K treatments. However, these low K treatments had significantly less Microdochium patch than the treatments receiving K applications during the past three winters. Plant tissue K content was below 1.5% in treatments with the least Microdochium patch compared to tissue K content between 1.8-2.2% in K treated plots. Mehlich-3 K was near 20 mg/kg in the no K treatments and ranged from 25-50 mg/kg in the treatments receiving K. No significant differences in other diseases including dollar spot or brown patch were observed during the study. Results suggest that potassium fertilization can be manipulated to reduce Microdochium patch severity on creeping bentgrass putting greens.