Your lawn can be susceptible to many diseases throughout the year, some are a result of poor lawn maintenance and care, which can be easily prevented and repaired, whereas others will appear with no fault of your own.
So even if you’re doing everything properly – mowing regularly, fertilising at the correct times of year, aerating, scarifying and watering exactly when your lawn needs it – you could still see a few Fusarium Patches popping up now and again.
Lawn diseases aren’t the prettiest of things to be seen on a lawn, so I think you’ll want to know how to limit your exposure to them as much as possible.
Below I’ve listed 5 most common lawn diseases to be seen in the UK, making it easier for you to identify and treat them.
This very common, cool weather disease enjoys the persistent drizzle and foggy conditions known all too well for us in the UK during the autumn and winter months. This is exactly when you’re most likely to see Fusarium Patch. But don’t forget about it for the rest of the year, it can cope with temperatures up to 12 – 19°C/54 – 66°F, so you may also see it popping up during spring and summer as well.
If you start seeing small, circular, yellow patches appearing on your lawn, that can sometimes grow to 30cm in diameter; you can be pretty sure it’s a Fusarium Patch. Once the patch is established it’ll begin to turn a darker and dirtier shade of yellow and can eventually kill the grass beneath it, but only in severe cases.
During wet conditions the disease will begin to get even worse as a white or pinkish cottony fungus can begin growing, especially at the edges of the patches. After the disease has become inactive, without treatment, the area left behind will appear pale and straw-like. Definitely something you’ll want to avoid so make sure you follow the tips below.
- Rake the damaged patches to clear the dead grass and expose the soil.
- Densely spike the affected area using garden fork to about 2cm to 5cm deep, this will let water, air and nutrients into the grass roots.
- Add a matching seed with some topsoil to the area, to make it flat at about 10 to 20 seeds per square 6cm to replace the old and dead grass roots.
- Brush then tread the seed in.
- You can then apply a fertiliser if the entire lawn isn’t affected.
- Make sure you keep this area damp and mow on a higher setting with sharp blades for the first 2 months.
- You might also want to prune any overhanging branches to improve airflow around the patch.
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For most homeowners that do take proper and regular care of their lawn, you’re unlikely to be affected by Fusarium patches. The disease is most commonly seen on lawns that have a high thatch layer, poor drainage and limited air movement, these are very poor conditions for grass growth which is why they are the most susceptible. So if you’re a keen gardener, you shouldn’t need to worry about Fusarium Patch.
This disease is very similar to Fusarium patches, in fact the only real difference between them is that Snow Mould will be seen after snow fall. It spreads rapidly during the cold seasons, especially if the lawn is covered by snow as air circulation is impossible. The disease thrives when the circulation is poor so it isn’t just snow that can be the culprit, if you have over 5cm of thatch lying on the lawn, then you’re likely to see it too.
If after the snow has melted you see white patches around your lawn then you probably have snow mould, which can even look pink in severe cases.
- Gently rake the grass so that air can get into the soil to promote new grass growth.
- Densely spike the affected area using garden fork to about 2cm – 5cm deep, this will let water, air and nutrients into the grass roots.
- Add a matching seed to the soil at about 10 to 20 seeds per square 6 cm to replace the old and dead grass roots.
- Brush then tread the seed in.
- You can then apply a fertiliser if the entire lawn isn’t affected. Make sure you don’t use a fungicide, in most cases they won’t be necessary and they aren’t organic so won’t be great for your lawn.
- Make sure you keep the repaired area damp and mow on a higher setting with sharp blades for the first 2 months.
- Also if thatch is the problem and not snow then make sure you scarify the lawn with a suitable scarifier or lawn rake.
- Make sure you carry out all of these procedures during spring, preferably around March.
To prevent the disease from appearing again the following year, I recommend applying a slow release nitrogen fertiliser (organic preferably) that has a good supply of potassium. Just make sure you don’t apply it too late in the year, as this can actually promote Snow Mould. For those in the South of the UK, it’s best for you to apply no later than November, and for those in Scotland in the North, we should apply it no later than October because of the colder weather.
Also known as leaf blight, leaf spot affects lawns all over the UK and can be caused by a number of different fungi. You’ll most likely see it appear at the end of spring and during summer as it favours warm and humid conditions, and will spread rapidly during times of rainfall as the spores of the fungi will be carried from leaf to leaf by water splash.
In most situations leaf spots won’t kill your grass and once it stops developing the turf will recover. But if the conditions get really wet and cold for a long period of time, say 2 weeks, then it can become so bad that it does kill the turf, especially if it is under fertilised. As it can be caused by a number of different fungi, most of them behave very similarly and because of that you can treat them pretty much the same.
Just watch out when you do notice Leaf Spots, they are easily spread if you are aerating, mowing or even just walking across the lawn. The spores are just too small for you to see, only after they’ve attacked your grass will you notice them. They produce small yellow spots on the leaves which can eventually turn tan or even black sometimes with a red border, which you should easily see – so keep your eye out for them.
A stressed plant is more likely to be affected than a healthy one, so if you make sure the grass is well maintained and properly watered then you should be OK. Also make sure when you’re mowing to have the blades nice and sharp and don’t cut the grass too short, this makes it easier for the disease to spread. Also, if your lawn suffers from thatch then consider aerating and scarifying it to ensure proper drainage, this will also allow nutrients and airflow reaching the grass roots.
This lawn disorder can be seen in a few varieties and can come in complete circles, ribbons or arcs. These are areas of stimulated growth that can be associated with bare patches of turf and toadstools (mushrooms). Even though the way these are contracted are quite similar and can often have the same effects, they do tend to look different.
There isn’t always an obvious cause explaining why these Fairy Rings appear, but in most cases it is because of rotting wood or root in the soil. As the roots rot under the soil, it develops mycelial spores that work their way up to the turf surface. This mycelial then become hydrophobic which in turn makes the soil water resistant, worsening the problem. It’s because of this why the disease is so hard to treat.
This is the most common kind and is most evident during dry weather. It is a ring of dead grass bordered by healthy grass and is often populated by moss and toadstools. If you take a sample of the affected area, it’ll smell musty and will have white specks of fungal growth upon it.
These specks cause the lawn to become water repellent, which is why you’ll notice the grass falling off, not because the fungus attacks the grass but because the grass cannot get any water. This makes it very hard to treat if the ring has completely dried out, the grass will be difficult to re-wet so you might have to wait for rain in the winter months.
This is seen as a perfectly green and luscious ring of grass that is sometimes growing toadstools. There isn’t much you can do about these rings as there aren’t many remedies for them. Although they can be masked to a certain degree by maintaining a good fertiliser and iron content.
This form is just a ring of toadstools, usually only seen during spring or autumn in times of wet weather. Again there is no known remedy for this kind of Fairy Ring but regular picking, brushing and mowing the affected area can prevent the spores from appearing again.
This lawn disease is probably the most well-known, it attacks leaves and will cause excessive damage, however it won’t attack the entire plant so recovery is usually pretty good. It thrives on plants that are suffering during stressful times, mainly during late summer or early autumn in the wet and warm weather.
This disease is usually seen as the grass leaves begin to turn yellow and if you look a little closer you’ll notice an orange speckling on the leaf surface. These are fungal spores that are ready to be transferred to a new set of grass leaves. However this colour can change, in autumn the fungus can turn black containing over-wintering spores.
If you happen to walk over an effected area then your shoes and clothes might turn orange as they become coated in the spores. Try your best not to drag the fungus to other areas as this will just cause more problems. I recommend that you wash your shoes.
In the most severe cases you will notice the grass leaves turning brown and shrivel up but it shouldn’t kill the grass.
- Feed the lawn on a regular basis during the growing season to help the lawn maintain its strength and health.
- Ensure you use appropriate seasonal fertiliser on your lawn to provide the grass with a boost of nitrogen. This will ensure the grass grows faster, allowing you to cut more regularly allowing you to remove the disease from the lawn through cutting.
- Mow regularly to reduce the number of affected leaves and always remove clippings.
- Aerate in spring and autumn to create holes for water, air and nutrients to penetrate deeper into the soil.
- Improve the air circulation around the affected area by pruning overhanging trees and shrubs.
Red Thread is a disease that is most common after periods of wet weather, especially near the end of summer when humidity is high. Just watch out though, the drying effect of summer can disguise the disease at which point most people just assume their lawn is suffering from drought and not Red Thread. The lawn will begin to show small patches of grey-brown turf at first, but if you look a little closer you’ll see little red straws sticking out from the leaves.
If you notice Red Thread in your garden, it is highly likely that thousands of other lawns are suffering from the same problem at the same time, as this is mainly due to climatic conditions.
The thing is not to worry too much about Red Thread, as it only affects the grass blades and not the roots.
Although humility is the main cause of Red Thread, poor lawn maintenance and condition will also exacerbate the disease. This includes poor cutting regime, thatch, soil compaction, poor drainage, lack of feeding and using a blunt lawn mower blade.
Even though the grass can start to look pretty poorly, this disease won’t kill it entirely. It just turns the grass a little straw like, especially when the disease is what caused the damage and dried up. Red Thread will rarely kill any of the grass.
To take care of the damaged areas there are a few thigs you can do:
- Applying nitrogen to the affected area will often be sufficient to control the disease. Just make sure you don’t apply after August, this will avoid the production of soft growth which is prone to snow mould.
- Scarifying the turf will remove thatch and moss and will increase aeration, which will reduce the threat of Red Thatch.
- Poor drainage and compacted soils can be alleviated by forking or by the use of a solid or hollow tined aerator, which also reduces the threat of Red Thatch.
- Make sure you dispose of the grass clippings gathered while mowing by throwing them away, don’t put them in your compost bin. This reduces the amount of fungus present to re-infect the lawn. (if you have a mower with a mulching plug do not use it at this time)
- If you’re fertilising on a regular basis and still receive Red Thread then this is just the lawn telling you that it’s still running a little low on nutrients. At this stage it is advisable to do a lawn soil test.
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In this article I have included the most common lawn diseases in the UK. Although these diseases do not look particularly attractive on your lawn, when they appear, it is not the end of the world as they can normally be eradicated by simply improving the health and condition of your lawn.
A mulching lawn mower is a great way to keep your lawn healthy and resilient to disease. Why not take a look at my best mulching mowers I have tested. Also you will need to ensure that the blade on your mower is sharp to ensure a clean cut. Avoid cutting your lawn too short, always follow the 1/3 rule (only cut 1/3 of the length of the blade).
It is also a good idea to carry out a soil pH value test to understand what is missing or what needs to be reduced in your soil to ensure healthy grass growth.
If you would like to learn more about seasonal lawn maintenance click on the links below, as prevention is always better than cure.
I hope you are now more knowledgeable about lawn diseases; if you have any questions please use the comment box below and I will be happy to respond.