I'm at snow-covered Hokkaido for some seminars this week and one of the things I have mentioned in the seminars is the possible increase in snow mold damage that can occur with high rates of potassium application in the fall season. Dr. Kerns mentioned the research being done at Cornell now to investigate this phenomenon.
We came across this observation on an L-93 field trial that we had designed to study soil testing methods, not snow mold. What we found, as you see below, is that plots treated with potassium in the previous year (and to which no fungicides were applied to prevent snow mold) had an increase in snow mold damage compared with plots to which no potassium had been applied in the previous year.
we observed a linear increase in gray snow mold damage with increasing rates of potassium application.
Hokkaido has heavy snow mold pressure. Many of the golf courses are under snow for four months. The photo below shows the effect of fungicide application in the fall (at right) vs. no fungicide (at left) in the snow mold damage to a golf course rough at Obihiro in mid-May. Clearly, one would not want to exacerbate the disease intensity by unwarranted application of potassium.