Q What is snow mould?

A Snow mould is a turf disease commonly seen on lawns that have been damaged by frost and snow. Snow mould is caused by the fungus Monographella nivalis. This fungus has had several different names in the past, including Fusarium nivale, so the disease is also known as fusarium patch.

Caption: Snow mould usually occurs in winter or spring

Q How do I recognise snow mould?

A Snow mould first appears as round, brown patches about 30cm across, which may be scattered over a wide area, or merge to create larger areas of dead grass. The affected grass can feel slimy, and pale-grey or pinkish fungal growth can often be seen.

Q Could I mistake snow mould for anything else?

A Dead patches in lawns can have many causes. Snow mould is the most likely disease to appear in winter or spring, and the appearance of fluffy fungal growths helps to confirm the diagnosis.

Q What damage does snow mould do?

A Snow mould can wreck the appearance of a lawn in winter or spring, but it rarely kills the grass, so the effect is only temporary. As the weather improves, with good cultivation, the grass will recover. Snow mould also affects winter cereals, particularly winter barley.

Q What is the life cycle of snow mould?

A The greyish or pinkish growths are the fungal mycelium, which can survive on plant debris. The mycelium can also produce spores that are able to survive in the soil, and can be spread by air or water.

Q When do snow-mould attacks occur?

A Snow mould often appears on lawns as they are exposed by melting snow, and is generally worse in spring after cold, wet weather, though it can appear at any time when conditions are cool and damp. Bentgrass, fescues and perennial rye grass can all be affected.

Q How do I control an attack of snow mould?

A The fungicide trifloxystrobin, available as Lawn Disease Control from Bayer Garden, will help to control snow mould and can be useful in dealing with minor outbreaks before they spread. Otherwise good cultivation is just as effective, encouraging the grass to grow out of the problem. In particular, anything that will improve air movement, such as raking up leaves and cutting back overhanging plants, should help recovery.

Q How do I prevent snow mould in future?

A Aerate the turf to improve drainage, therefore reducing the damp conditions in which the disease thrives. Avoid applying nitrogen-rich fertilisers in autumn, as these encourage soft growth that is more susceptible to the disease. Try not to walk on grass covered in frost or a thin layer of snow as the frozen grass is easily bruised, giving easy access to the disease. Keep the it strong and healthy with a good care routine.