Potassium Effects on Pink Snow Mold Incidence of Annual Bluegrass.

Microdochium patch (caused by Microdochium nivale) is a common disease on golf course turfs in cool, humid regions of the United States. A 2-yr field study evaluated the response of this disease to potassium fertilization on annual bluegrass [Poa annua L. f. reptans (Hausskn) T. Koyama] turf maintained at 2.8 mm on a sandy loam in North Brunswick, NJ. A randomized complete block design with five replications was used to evaluate three potassium sulfate treatments: K was applied at 0, 20.3, and 40.5 kg ha^-1 on 23 and 24 November in 2015 and 2016, respectively. Plots were inoculated with 8.6 and 4.3 g m^-2 of oats infested with M. nivale isolates PPCC12012 and PP42013 on 11 December 2015 and 12 December 2016, respectively, and covered with two layers of a permeable growth cover. Plots treated with either rate of K in 2015 had the same disease severity, measured as area under the disease progress curve (AUDPC) during the winter of 2015-2016, compared to the plots where no K was applied. During the winter of 2016-2017, AUDPC was reduced 13% in plots treated with 40.5 kg K ha^-1 compared to plots where no K was applied. This research will be continued during the winter of 2017-2018.