Lawn Problems & Advice

Weeds are the bane of most lawn lovers' lives; even using the finest herbicides available and the best application methods, it is not possible to remove all weeds in one go. There are a number of reasons for this: to eradicate weeds they have to receive a direct spray of herbicide, but where the weed count is high, the leaves of some weeds will cover and protect others. Also, the growing seasons and therefore the susceptibility of weeds to herbicides, vary between types of weeds.

Generally, you can expect over half of your weeds to deteriorate in any one treatment, therefore, after three or four treatments, most of your weeds will have disappeared. However, it is a never-ending battle to keep your lawn weed-free as seeds lie dormant and others are blown in from neighbouring locations; resulting in re-contamination of your lawn, so continued treatment is necessary.

Here is a selection of the most common lawn weeds, although your local operative will be able to advise you when he carries out a lawn analysis if you have anything more 'exotic'!

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Creeping Buttercup

Scientific Name: Ranunculus repens

Flowers fairly early on in the year, around April time and has vigorous rooting runners; common in damp lawns and clay soils.

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Lesser Celandine

Scientific Name: Ranunculus ficaria

A low growing perennial with heart shaped leaves. Flowers between February and May with a single yellow flower which only opens in bright sunshine.

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Common Mouse-ear Chickweed

Scientific Name: Cerastium fontanum

This is a prostrate annual with weak stems, which can grow up to 40cm long. It has white flowers, which flower from February to November.

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White Clover

Scientific Name: Trifolium repens

The bane of many gardeners' lawns, this weed has rooting stems which creep along the soil surface. Flowers are white and appear between May and October.

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Daisy

Scientific Name: Bellis perennis

One of the most common, and popular, lawn weeds, the daisy is a tufted perennial with tightly packed flowers. The flowers appear all through the year, peaking towards the late spring, and have a yellow central disk with white petals.

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Dandelion

Scientific Name: Taraxacum officinale

Easily recognised lawn weed with a single, solitary yellow flower, which sits on a fairly weak hollow stalk, and flowers from March to October.

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Plantain

Scientific Name: Plantago lanceolata/major

There are various species of plantain, which are common on bare ground but equally happy on grassland. This broad leaf weed grows close to the ground and is tolerant to trampling and mowing.

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Germander Slender Speedwell

Scientific Name: Veronica Chamaedrys

Very common in amenity grassland and turf, with creeping stems and small lilac flowers, with a white centre; flowers from April to June.

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Lesser Trefoil

Scientific Name: Trifolium dubium

Low growing but can reach lengths of up to 50cm. With 3 small, oval leaves and a tiny yellow flower, which appears between May and August.

Lawn disease comes in many forms; it is generally caused by fungus which attacks the grass and deprives it of vital nutrients. Red Thread is the most common disease, as well as Fusarium, Leaf Spot, Snow Mould and Rust, to name a few. They can all affect the lawn, causing discolouration, weakening of the plant and ultimately killing it altogether.

What causes lawn disease?

Disease is caused by the grass plant becoming stressed and therefore more vulnerable. Stress can be caused by many reasons such as: drought, moss, compaction or incorrect mowing.

It is recognised by a pink/reddish tint on the grass blade. Upon closer inspection, very fine needles can be identified protruding from the grass blades. In very severe cases you will see pink mycelium, almost like small flocks of cotton wool.

How can GreenThumb help?

Maintaining a healthy lawn is the best way to prevent lawn disease. Fortunately, if a lawn disease has taken hold, we can treat it with a fungicide which should bring it under control. However, prevention is always better than cure, so it is important to look at reducing the conditions which favour lawn disease.

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Red Thread

Red Thread can be seen through late spring and summer months during periods of high humidity. It occurs mostly after periods of wet weather, especially towards the end of summer, when humidity is high.

The lawn will begin to show small patches of grey-brown turf initially; on closer inspection, the grass plant will have small, red ‘needles’ protruding from the diseased leaf.

Although high humidity is the main cause of Red Thread, it can also be seen in lawns that are suffering from plant stress. This is usually caused by: poor cutting regime, drought, thatch, compaction, or lack of feeding. By ensuring a good care programme of feeding, cutting with a sharp blade on the mower, thatch reduction and aeration, this will help to keep it in check.

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Microdochium Patch (Fusarium)

Microdochium Patch (Fusarium) is another very common lawn disease, seen mainly, but not exclusively, during the autumn and winter months. This is a cool weather disease and enjoys persistent drizzle and foggy/misty conditions with low air movement.

Symptoms appear as small, circular, yellow patches which can spread up to about 30cm in diameter. Once established, the patches turn a yellow/brown colour and in severe cases can kill the grass. After the disease becomes inactive, the area appears pale and straw-like.

Lawns that have a high thatch layer and poor drainage, as well as enclosed lawns with little air movement, are the most susceptible to this disease.

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Leaf Spot

Leaf Spot is a very common lawn disease that affects lawns across the UK. It can also be known as leaf blight or net blotch. The disease can be caused by numerous different fungi and spreads rapidly. Warm and humid weather conditions are favoured by this disease and spores of the fungi are disseminated by water splash.

A stressed plant is more likely to be affected than a healthy one, so ensuring the grass is well fed and watered will help. Also ensure the mower blades are sharp and do not cut the grass too short. If the lawn suffers from thatch, consider having machine work - Aeration and Scarification will help to keep the sward healthy, thus reducing the likelihood of disease.

There are other pests that you may come across, and your local operator will be able to advise you accordingly.

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Dollar Spot

It was always thought that this disease was not found extensively in the UK, however reports are indicating that it is more prevalent than first thought. The fungus that causes this disease is known as Sclerotinia homoeocarpa.

Patches are usually very distinctive and often circular, and can coalesce to form large affected areas. Within the patches, dead grass is bleached white or straw coloured and they may also be sunken.

Conditions which favour this disease are warm and humid, plus heavy dews and low nitrogen nutritional levels. The disease also favours certain grass species such as slender or creeping red fescues. It has also been identified on many other species but these seem to be the most susceptible.

Culturally, the best advice is to cut the grass regularly at a high setting with a sharp blade, ensuring that there is not a lot of thatch present in the turf surface.

The best results are always achieved when the turf surface is kept dry so aeration may also play an important role.

Due to the fact that it is also encouraged when Nitrogen levels are low, then fertilising is important, particularly on light sandy soils, due to the potential for leaching.

The other approach to control is the use of an approved fungicide; the key to this working correctly is application and timing. The product that we use is an azoxystrobin, which works by systemically moving through the plant not only as a cure, but works to keep the plant healthier for longer.

In cooler weather, the suggested fungicide is Fludioxonil. As a contact this will work better during the dormant part of the season.

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Rust

This is possibly one of the oldest known turf diseases. It attacks the leaf plant and causes extensive damage. It rarely attacks the whole plant, so recovery is usually good.

This disease thrives on plants suffering from stress, and is most prevalent in autumn or early spring, when the weather is warm and wet.

If your lawn is looking under the weather, tired and not the right colour, speak to your local GreenThumb expert who will be able to offer great advice and solutions.

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Snow Mould

Very closely related to Microdochium Patch (Fusarium) is Snow Mould, another cool weather disease that thrives in lawns with poor air circulation. This fungal disease spreads rapidly during cool weather, especially under a blanket of snow, where there is no air circulation. When snow settles on a lawn for any length of time, it incubates the disease which can only be seen once the snow has melted.

The fungus produces white, dish-like patches which, in severe cases, can turn pink. It is not possible to keep snow from the lawn so be prepared to deal with this once the snow has melted. What will help is to get the air moving in the lawn as quickly as possible so a hollow-tine aeration can help, along with an application of a micronutrient to help the grass. The other option is an application of a fungicide which will stop its activity and, as the weather improves then, if necessary, action can be taken to help with the recovery of the lawn.

There are two specific pests that cause large issues on lawns in the UK, Leatherjackets and Chafer Grubs; some pests can cause minor issues such as worms and ants. The treatment we use for controlling Leatherjackets and Chafer Grubs is the biological control - Nematodes. The treatment we use for worms is an irritant that reduces the surface activity and this lessens the amount of casts produced. At the time of writing we have no specific control for ants however, we would advise using a spade, slicing into the lawn where the activity is and applying ant powder into the nest, pull out the spade and restore the crevice.

Worms are generally good for the lawn; there are 25 species however, there are only 3 that cause casts in the lawn. The process worms have by moving through the soil is good for microbial activity and aeration. The cast that they return to the surface can look ugly and be a good seed bed for weeds.

The liquid spray we apply acts like sand, which irritates the worms and by removing them from the surface; generally it does not kill them. This spray will need to be applied twice per year, once in the autumn and again in the spring when activity is at its height.

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Leatherjackets

Leatherjackets are the larval stage of what is commonly known as Daddy Longlegs (Crane fly).

Their one-year life cycle begins when the female lays her eggs in the lawn, around September time; they then hatch 2-3 weeks later.

Over the winter period, when the weather is still wet and warm enough, the larvae starts to feed on the top part of the grass plant’s root system.

At this time, the damage is not normally seen as the Leatherjackets are still quite small. It is important to note that secondary damage to the lawn can also be caused by birds and animals rooting for the grubs.

By February and March, the grubs will have grown in size and the damage will be much more extensive.

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Chafer Grub

Chafer grubs are the larvae of the Chafer beetle (May bug) and have a life cycle of 1-3 years, dependent on the species.

The females lay their eggs in the lawn. When first hatched, the grub is very small and at its most vulnerable. They are curved like the letter C, with white fleshy bodies, light brown heads, 3 pairs of legs and will grow to 10-15mm in size.

The grubs feed on the roots of the grass plant resulting in the turf becoming detached from its soil moorings, allowing the lawn to be pulled back, like lifting a carpet. Birds, badgers and a number of other animals enjoy eating these grubs so damage to the lawn can be extensive.

What is Dry Patch?

Dry Patch is best described as a waxy coating found in soils making the area hydrophobic; resistant to water. There is no clear reason why lawns get Dry Patch. It is not a disease as its not caused by a pathogenic organism.

Being hydrophobic, Dry Patch has a great impact on the grasses ability to use water and grow. Its effect is similar to polish on a car. Water just runs off.  

With water being very important to a lawns health, indeed any plant, then this disorder needs to be addressed.

How can I tell if my lawn has Dry Patch?

There are various ways of doing this:

• Looking at your lawn from an elevated position you notice areas of the lawn looking a darker colour than other parts of the lawn. This could be an indication of Dry Patch.
• If you water an area of your lawn and it stays on the surface this is an indication that dry patch may be underlying in the soil. If it does permeate the soil but very slowly it could be a drought issue which if not corrected, could deteriorate into Dry Patch.
• Examination of the soil- by taking samples- reveals the soil is extremely dry (sometimes almost powder like).
• Another identifying mark might be the presence of a whitish substance that looks chalky, known as mycelium. This will be related to Dry Patch too.

Does GreenThumb have a treatment which is specifically tailored to treat Dry Patch?

Of course, we do. This is our Oasis Treatment.

How can I prevent Dry Patch from happening in the future?

This is very challenging but using a good programme such as our Nutragreen of treatments regular aeration and scarification to ensure good soil movement along with the Oasis treatment programme and watering the lawn this should keep the incidence of Dry Patch to very low.

Toadstools/Mushrooms are the fruiting bodies produced by fungi that can be found in the lawn; most are generally harmless and occasionally can be beneficial to the eco system. Although the fruiting bodies are clearly visible it will take an expert to distinguish whether they are edible, so it is not advisable to eat them.

Toadstools in the lawn are not always a cause for concern, however when you get mushrooms in a circle then this could be evidence of a fairy ring, this is discussed on a separate leaflet.

What to do?

Before cutting the lawn try and remove these from  the lawn using either a rake or if the lawn is short enough a still brush will help, if you cut the lawn with them on you increase the risk of spreading the spores and increasing the numbers that may already be there.

We generally find good maintenance of the lawn with aeration and scarification reduces the numbers the following year, we also see high incidence of these when we are seeing extremes of weather, for example when it goes from dry and cold to warm and wet, the humidity will stimulate their activity.

It is also a sign that the microbial activity within the soil is high, this is good as it helps to ensure that when we are feeding the lawns the microbes are helping to share the food around the grass plant.

Fungicide

If you have heard that it is wise to apply a fungicide please ignore this practice, fungicides will have an impact on the fruiting bodies that are there for a short time; they will have no impact on the ones beneath the soil which can pop up over night.

What are Fairy Rings?

At one time there was a popular belief that when you see a darkening ring in your lawn this had been caused by fairies dancing on the lawn. We now know this is not a fact! There are typically three types of Fairy Rings on a lawn.

A ring of:

• mushrooms only
• darker coloured grass with mushrooms at the edge of the circle
• dead grass, with mushrooms at the edge.  This is the worst type.

How do I know if my lawn has a Fairy Ring?

Look for the signs outlined above. Trying to water the area would probably show that it is not allowing water to penetrate the surface due to the soil becoming hydrophobic. Taking a soil sample from the area will show white fungus in the soil and no moisture in the area at all.

What can be done if my lawn has a Fairy Ring?

Fairy Ring are not easily controlled due to challenges caused by their source, a measure of control can be gained by treating the areas with a soil fungicide and a good water conserver.

GreenThumb will recommend the best approach as the treatment will be commensurate with the severity of the condition. There isn’t a one size fits all solution and we would like to give you the best advice for your Fairy Ring.

Mowing is the most important practise in maintaining your lawn. Correct mowing can make a huge difference to its health and how good it looks, even with lawn treatments.

Mowing tips:

• Cutting the grass very short can have a negative impact, as it will weaken the grass plant and encourage lawn disease, weeds and moss
• Don’t cut your lawn too short - less than 25mm (1”). This should be increased to at least 50mm (2”) during dry spells
• Remove grass clippings as they contribute to surface thatch if left on the lawn, which in turn encourages moss
• Always sharpen or replace your lawn mower’s blade regularly, so it doesn’t tear the grass blade
• Clean and remove grass from the underside of the mower after use
• Never remove more than one third of the total height of the grass in any one cut.

Does GreenThumb have a treatment which improves the lawn and recudes mowing? - Yes it's called SlowMow.

Plants love water. Lawns are plants too. Lawns love water.

Thankfully our climate means that occasions we actually have to get the hosepipe out are not more than a few times in a year.

Today there are inexpensive and clever little timers you can attach to a hosepipe which time and regulate the amount of watering without you having to stand on your lawn waving our arms from side to side. Your local garden centre and even Amazon sell them.

Watering in Dry Weather

In periods of dry weather, the lawn will thank you for a drink. Earlier in the morning or evening is probably the best time to set the timer for the sprinkler to come on.

Water the lawn long enough for the lawn to have had a good soaking. Its difficult to say how long this is as lawns differ in their exposure and makeup. But if you pushed us to make a recommendation it would probably be between 20-30 minutes.

So, set the timer for 20 minutes every day or 30 minutes every other day depending on how hot the weather is.

Lawn Mowing in Dry Weather

The most common mistake we come across in periods of dry weather is homeowners cutting the lawn too short. In periods of dry weather our advice would be please, please don’t cut your lawn. If you have to… set the mower height to at least two inches.

The lawn will thank you. It will stay greener much longer, make more efficient use of the watering and recover quicker.

Does GreenThumb have a special treatment to help with dry weather and make the best use of lawn irrigation?

Funny you should ask… Yes we have. It’s called Oasis.