In fall usually, but at other cool, damp periods in the year also, small water-soaked patches of brown or yellow-brown grass appear, particularly on Poa annua. After snow melt in spring the patches may turn pink on exposure to light. Found in all regions. In general: snow molds (including pink snow mold, gray snow mold, snow scald and cottony or LTB/SLTB snow molds) are caused by low-temperature tolerant fungi able to grow at temperatures at or below 0 C.
- unbalanced or excessive nitrogenous fertilizer, particularly if applied late in the growing season
- alkaline tuff surface
- high surface moisture
- cold, humid weather or early snow in fall
- warmth from nearby buildings
- susceptible Poa annua and Agrostis cultivars; Kentucky blue grass often attacked, but rarely killed out
- deep snow cover provides insulation and high humidity favorable to development of snow mold fungi, and prolongs the periods of attack
Let turf "harden off" for winter. Keep mowing into late fall. Rake off fallen leaves. Give adequate, balanced, but not excessive or late fertilizer. Avoid the use of materials which rapidly raise turf surface pH, e.g. lime, or alkaline-tending fertilizers. Open up hedges or dense windbreaks to improve air movement. Replace susceptible cultivars with more resistant ones. Penncross is less susceptible than Seaside bent grass in Prairies and B.C.; creeping bents are less susceptible than brown top cuItivars. Control snow cover with fences and spread snow drifts. Encourage rapid melting of snow with applications of soot, fine ashes or other finely ground, dark materials in late winter.
For information about other diseases that affect turf grasses, go to Major Diseases of Turf Grasses in Western Canada.