Turf Diseases

Identifying these diseases

• Coloured patches in your turf?
• Has it been less than 7°C for several weeks?
• Has there been much rain or snow over the last few weeks?
• Is it springtime (March, April or May)?

If you can answer yes to those questions, it is likely that your turf is infected with a snow mould.

Background
Snow moulds are fungi that are attack your grass when the air and soil temperatures are cold and grass is incapable of much growth.

Many different fungi fall into this category, but they all need several months of cold, wet weather to flourish and are thankfully relatively rare as a result - even in the UK!

If the weather is warm and dry enough for the grass to grow, snow mould can't attack grass. These fungi naturally occur in your turf, making them difficult to control unless you regularly apply fungicides.

Amongst the many varieties of fungi that attack grass when it is are cold and wet, the most common are grey snow mould and Fusarium pink patch - which is also sometimes known as pink snow mould. Both of these diseases start to develop in the autumn, but can generally only be identified in the winter through to the early spring.

There are other, more rarely occurring snow mould diseases, but identifying them requires an expert eye. But - determining whether grey snow mould or fusarisum pink pathc is attacking your grass is very important. The two diseases develop differently and required different treatments.

Grey snow mould
If you are a bit of a scientist, you can identify grey snow mould by its grey mycelium, tan grass leaves, and formation of sclerotia! For us mere mortals, mycelia are very tiny hair-like tubes that form part of the fungus. Individually, they are almost microscopic. However, in large quantities they are visible with the naked eye. Your best chance of spotting and identifying them is on wet mornings.

Spiders, insects and other organisms can produce things that look like mycelium, so you do have to be a little bit careful in your diagnosis.

To help you, grey snow mould also produces sclerotia. These are small, hard bodies that protect the fungus from drought and heat, and are about the size of a pinhead. If you look amongst patches of dead blades you are most likely to be able to see them. Sclerotia are only found after 3-5 months of cool wet weather. Look for them in the early spring, but don't be surprised if they are not visible, sometimes they don't form at all.

Fusarium pink patch
Like grey snow mould, this disease also requires cold, wet weather. It is however faster growing, needing only around a month to appear. It also produces mycelium, but handily for identification purposes it is often pink or red - from which it takes its name.

Rather than produce sclerotia, this species of fungus actually produces millions of tiny spores - the method by which it reproduces and propogates.

Reducing the severity of snow moulds before it is visible
Put simply, prevention is the best cure.

• Stop fertilising your turf ahead of the time when the grass stops growing in the autumn.
• Ensure that your turf is evenly and frequently mown throughout the year ahead of your final autumn mow.
• Do not walk on grass when it is frozen turf. This can damages the blades and leave the grass vulnerable to snow mould fungi.
• If your lawn was infected with snow mould last year, then consider a fungicide treatment in the autumn. Timing the application of fungicides to is tricky, because you must figure out which snow mould disease you have and apply the correct fungicide about the time the disease starts developing. If you are worried about a recurring infection, it is best to consult a turfgrass expert for help.
• It is always advisable that you obtain advice about chemical grass treatment products from the manufacturer.

Reducing the severity of snow moulds before it is visible
Because snow moulds require cold, wet weather they can continue to develop into late winter or even early spring. However in most years as soon as the grass begins to regrow, snow mould diseases will disappear as they cannot thrive in living grass. Therefore, the best way to remove snow mould patches is to encourage grass growth by applying fertiliser and beginning mowing. If you like, raking infected areas will encourage the turf to grow quickly and shrug off the infection.