Anthracnose lawn disease

Anthracnose is caused by the fungus Colletotrichum graminicola. It can attack most species of grass on the lawn butannual meadow grass (Poa annua) is very susceptible (hence the previous name of this disease was 'Basal rot of Poa annua'). Antracnose is a stress disease attacking grasses that are under stress due to environmental factors.

Identification of anthracnose

Anthracnose usually appears on the lawn during the late summer and can persist well into winter, even into the following spring. Be vigilant and look for annual meadow grass plants that are starting to turn yellow, with the youngest leaf turning an orange to red colour on infected plants. As the severity of this disease increases the patches can grow to 150mm in diameter and the base of the infected area turns black.

Causes of anthracnose

As we previously mentioned anthracnose is a stress disease so pay attention to keeping the lawn in a healthy condition with good lawn care practices.

• Ensure the lawn receives adequate nutrition, (however it is important not to over apply nitrogen during the late summer and autumn as it may lead to problems with fusarium patch disease).
  
• Soil compaction can also influence anthracnose.
  
• Prolonged leaf wetness will encourage anthracnose to spread.
  
• Hot and dry conditions leading to drought stress, will encourage anthracnose.
  

How to prevent and cure anthracnose

To put it simply pay attention to remedying the causes of anthracnose

• Ensure the lawn receives adequate nutrition to keep the grass in healthy condition.
  
• Relive compaction with aeration, in the form of slitting, spiking or even hollowtining.
  
• As anthracnose predominantly attacks annual meadow grass reduce the amount of this grass in the lawn by encouraging disease resistant grasses with good lawn care management practices.
  
• Raising the height of cut on the mower will also help reduce the stress levels of the grass and help combat the spread of anthracnose.
  
• Reduce the time that the leaf surface remains wet by removing early morning dews.
  

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Fusarium patch disease

Fusarium patch disease is the most common and one of the most damaging lawn and turf diseases. It predominantly occurs in the autumn and winter months between October & March, however it can strike at any time of the year especially if the conditions are favourable for fusarium.

The disease is less of a problem on general purpose lawns, fusarium patch disease attacks closely mown luxury lawns that contains a high percentage of annual meadow grass, this grass species being very susceptible to attack. The disease is a widespread problem on closely mown sports turf such as golf and bowling greens.

Identify fusarium patch disease

Fusarium patch disease initially appears on the lawn or in areas of turf as small patches that measure up to 50mm in diameter. The leaves turn an orangy - brown colour and are mushy. Sometimes during early mornig dews, white cobweb like fungal threads can be seen on the infected areas.

As the disease quickly spreads the patches increase in size into larger patches that measure up to 300mm in diameter. As the severity of the attack increases, these patches can join together causing widespread damage to the lawn.

Conditions that favour fusarium patch disease

• Fusarium patch disease is most active during the cool and damp weather conditions typically associated with the autumn and winter months.
• Excess levels of nitrogen caused by late season applications of high nitrogen feeds will encourage fusarium patch disease.
• Areas of turf and lawns that suffer from shade lack sunlight and air movement, encourage fusarium patch disease.
• An excessive layer of thatch or organic matter build up encourages water retentive turf which in turn encourages fusarium.
• Surface alkalinity (high pH) caused by applications of lime or other materials with a high pH leaves the grass susceptible to this disease
• A lawn that contains a high percentage of annual meadow grass will always be at risk from an attack of fusarium, as this grass species is very susceptible.

Prevention and control of fusarium patch disease

• Fungicides are available for turf care professionals such as golf green keepers. Unfortunately for amateur gardeners the use of fungicides is severely limited and in many cases not allowed, therefore preventing fusarium patch is all the more important.
• Excess nitrogen is a contributing factor in many diseases including Fusarium patch disease. Avoid applying fertilisers with a high nitrogen content to late in the growing season.
• Apply an autumn / winter fertiliser at the end of the growing season with a high potash content. Potash is an important element for the grass plant during this period as it helps harden the plants against disease.
• Where possible prune back vegetation to allow more air and light into the garden. This will help keep the leaf of the grass dry which is important in preventing this disease from spreading.
• Regular mechanical operations like aeration and scarification are important to help control the thatch layer, thus helping in the fight against fusarium patch disease.
• Applications of sulphate of iron based products will help lower the surface pH therefore discouraging fusarium.
• Encourage grasses that are able to tolerate the disease as the expense of annual meadow grass.

A proper lawn maintenance program will be geared towards encouraging bent and fescues at the expense of annual meadow grass. Annual meadow grass is very prone to fusarium patch, whilst bents and fescues are more tolerant to the disease Gear your lawn maintenance program to promote healthier sward helping it withstand disease and many other turf care problems. In the world of professional turf care fungicides are used to control fusarium. However amateur gardeners don't have access to these products, this makes the cultural preventative measures all the more important. Fungicides can only be applied by turf professions with the relevant spraying certificates.

Chemical control of fusarium patch disease

Turf professionals  such as golf greenkeepers and groundsmen have a big advantage over the amateur gardener, as they have access to a range of turf fungicides in their fight against disease. Many people prefer to spray a preventative application when the conditions are conducive to an outbreak of fusarium patch disease.

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Lawn Disease

A lawn disease or turf disease is often defined as anything that has a negative effect on the grass plant. Lawn Disease, the majority of which are caused by fungi can attack all types of lawns and turf areas. Different diseases attack luxury lawns and other will attack utility lawns depending on the environmental factors and types of grass in the lawn.

For a lawn disease to become active 3 factors must be present.

• Environmental factors - Grasses can become stressed by different climatic & maintenance conditions leaving them susceptible to lawn disease. It may be too cold, too dry or too wet, however these conditions are out of our control. Other factors such as mowing heights, drainage, turf nutrition and irrigation needs can be controlled by us and can play a big part in a successful prevention plan.
  
  
• The soil pathogens -Pathogens are the fungi or bacteria that cause lawn and turf disease. Many of these pathogens are already present in the organic matter, becoming active if favourable conditions occur to cause an outbreak of disease. Pathogens can also spread from outside agencies such as other lawns, playing-fields, parks amongst others.
  
  
• The grass species -Different species of grass are susceptible to different diseases. e.g. Annual meadow grass suffers from fusarium, and anthracnose, bents suffer from take-all patch, fescues from red thread etc.
  

This lawn disease section covers the most common diseases found on lawns and turf throughout the UK. These include:

• Fusarium Patch 
• Red Thread
• Take-all Patch 
• Anthracnose
• Dollar Spot
• Fairy Rings
• Slime Mould

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