What goes for most lawn diseases also goes for fungal infestations: the better the lawn is cared for, the harder it is for weeds, fungi etc. to take hold. However, fungal infestations cannot be avoided entirely in this way, since the spores can be carried by the air and by rain, as well as through contact with people and animals. The number of fungal diseases is almost as numerous as their causes. These primarily include:
- Particularly dense growth
- Continuously intensive use (e.g. sports fields, but also walking on the grass too frequently during winter)
- High humidity, water-logging
- Excessively dense mulch
- Incorrect soil pH
- Lawn thatch
- Excessively short mowing
- Shady areas, high walls, wood
- Failure to collect leaves or excessively tall grass during winter
- Oversupply (water, fertiliser)
Combating fungi can therefore start with preparing the soil and selecting the right type of grass. In keeping with the motto "Do it right first time", this is not the place to economise: you should use standard seed mixtures. When selecting the type of grass, the future use plays a big role in addition to quality. For example, you should definitely use more resilient grasses if the local football team hold their daily training sessions in your garden!
But what to do if fungi still take hold? No need to worry; most fungal diseases are harmless and the only damage they cause is cosmetic. Fungi that become established in grasses can often be killed off simply by ventilating (scarifying) the lawn (e.g. snow mould). The pH should also be checked; if it is too low, a measure such as liming can help. However, it is imperative that the general condition of the soil is taken into consideration; sandy soil or loam have very different needs – what's good for one isn't necessarily good for the other.
For lawns where fungal colonies have already taken hold, the only thing that will help is to dig them out – making sure to take a large area and include all root remnants. Under no circumstances try to remove the fungi by mowing the grass short! Grass that is too short encourages the growth of the pests and, in a worst-case scenario, mowing the grass will distribute the pathogens further throughout the garden. You should only consider using fungicides, most of which require repeat applications, if the infestation keeps recurring. Caution should always be exercised when using chemical products as these can pose a risk to the ground water if used incorrectly. It is preferable to seek advice from experts here rather than rushing into action.