Lawns in damp conditions can suffer from these unsightly problems.
Lawn lichens and algae
The most common lichen found on lawns is Peltigera canina or dog lichen (left). This is a greenish-black or greyish leaf-like structure that grows horizontally in the turf.
Lawn algaes are usually dark green or blackish in colour, forming a gelatinous slippery layer over the surface of the lawn.
Lichens and algae flourish in poorly drained lawns but can develop during wet conditions and are frequently found on turf beneath trees.
Slime moulds
Wet weather in autumn or spring can also lead to the growth of slime moulds. These growths, which may be white, yellowish or orange, produce small grey fruiting bodies that subsequently release masses of purplish-brown spores. The growths are purely superficial and do not harm the grass but they are unsightly.
Reducing waterlogging
Localised compaction can cause waterlogging and may be relieved by spiking with a garden fork or solid-tine aerator. Repeat the treatment as necessary at four- or five-week intervals when the soil is moist. Hollow tining may be required on heavier soils and should be carried out in autumn.
If soils remain waterlogged all year, artificial drainage should be considered. Avoid walking on the lawn when it is waterlogged as this will only aggravate compaction.
Chemical control
There are few chemical controls but if lawn mosskillers that contain ferrous sulphate are used on the lawn to control moss, incidental control of lichens and algae should also result.
Helen Bostock