by Leslie Cox; Friday; January 6, 2017
This is a little bit of follow-up information to my article “Beware of Snow Mould”, which appeared in my Duchess of Dirt column, in the Comox Valley Record, on January 5, 2017
Snow mould is a fungus disease that attacks your lawn after it has been buried under a load of snow for long periods of time. Hence its name. But it can also occur if you have left leaves and other debris on your lawn over the fall and winter periods.
There are actually four types of snow mould:
- Sclerotinia – Sclerotina borealis; Myriosclerotina borealis
- Pink – Microdochium nivale; Fusarium nivale
- Grey – Typhula incarnata
- Cottony – Coprinus psychromorbidus
The two which typically attack urban lawns and golf courses in our part of the country are grey and pink moulds. Grey mould is more common than pink, thankfully, as the pink variety is more deadly to our lawns.
Symptoms of grey mould infection will start to show up sometime after the snow has melted. Patches of light brown appear in a rough circular shape which can be up to two feet (60 cm) in diameter. The infected grass may be matted and show a greyish-white fungal growth. As bad as it may look, it rarely kills the grass.
The disease cycle for Typhula blight is reversed to most other fungi species. It lies dormant in the ground in resting structures, called sclerotia. Late fall, when conditions are more favourable to Typhula blight growth, the sclerotia start producing basidiocarps which produce spores. The mycelium from these spores are what grow to infect new blades of grass which are covered over with deep snow.
Once infected, repeat infections are likely to occur if remedial action is not taken. So…how to cure? Luckily, much can be done organically, without resorting to chemicals.
First, do not fertilize your lawn after August….even if lawn care gurus tell you it is mandatory for healthy lawns. Adding nitrogen, including spreading compost on your lawn, coming into the fall season only presents ideal growing conditions for the fungus.
Second, keep mowing your lawn…right up until it has stopped growing…then mow it at least one more time.
Third, rake up all leaves and debris off the lawn. It is called good housekeeping!
Fourth, if you get a dumping of snow…or a whole many dumpings of snow…do not pile the snow on the lawn area when you shovel the walkways and driveway. Try to find somewhere else to pile the accumulation of white stuff, but not on your neighbour’s yard.
If you have followed all of those steps, but still find infected patches come spring thaw…rake the matted grass area in order to encourage new growth. You may also want to throw down some new grass seed.
Unfortunately, all grass varieties are susceptible to infection from Typhula blight. However, some are a little more resistant than others.
These include: red fescue, Kentucky blue grass, and perennial ryegrass. Creeping bentgrass, velvet bentgrass, and tall fescue are more prone to infection.
Hope this has been helpful…should your lawn be infected this year…or in any other heavy snow year. But hopefully not!
