Pink and grey snow moulds are devastating turf diseases that occur on golf course putting greens, tees, and fairways in the presence of snow cover. These diseases are not only unsightly in the spring but can leave the turf surfaces unplayable. Both pink and grey snow moulds can affect all cool-season turfgrasses but tend to be more problematic on annual bluegrass and creeping bentgrass. Now is the time to start planning for snow mould applications. You only have one opportunity to control snow mould, so here are some quick points to make your one chance count.
Help maximize turf health going into winter - Like with most turf diseases, snow moulds are more damaging on turf that is at less than maximum health:
- Aerify to reduce compaction and help limit thatch
- Continue nitrogen fertilization into the fall via spoon feeding on greens or modest fall applications of nitrogen on higher mowed turf
- Maximize water movement off turf by removing "sand dams" at edges of greens or any obstacles that may limit snow melt from moving off greens, tees and fairways
Check calibration and spray coverage - a full season of applications may wear out nozzles and the impact may not visible until snow mould break thru occurs early next spring.
Use the highest practical labeled rate - reducing the fungicide rates will reduce concentration of fungicide in the plant, especially late in the winter. Most snow mould damage occurs late in winter with warming temperatures, usually corresponding with decreasing concentrations of fungicides.
Use two or more active ingredients - researchers agree that more active ingredients in your snow mould control strategy will improve overall control.
Consider a primer application to reduce inoculum - snow mould symptoms develop most commonly under snow cover and temperatures at 0-10°C, but sclerotia (Figure 1) begin to germinate in the fall at 10-18°C air temperatures. Controlling the early inoculum with one or two fungicide applications prior to the final application will limit later infections and improve long-term control.
Protect young turf - fall-seeded turf is usually heavily fertilized to hasten establishment, but this also makes it succulent and especially susceptible to snow mould in the late fall. Be extra cautious with young turf and protect it with preventative snow mould applications.
Consider reapplying after heavy rain - if significant rain (>25 mm) falls between the final fungicide application and snow cover, consider making another application to maximize disease control and ensure a successful start to the 2020 season.
The following table shows recommended products or mixtures for greens, tees, and fairways based on the type of snow mould and length of snow cover expected.*