A fungicide is a chemical or biological product that can be applied to grass to reduce the effects of unwanted fungal diseases. Common fungal lawn diseases include anthracnose, red thread, fusarium, take-all patch, brown patch, pythium blight, dollar spot, fairy rings, leaf blight, and rust. The term ‘fungicide’ covers a variety of products from chemical compositions that directly target and kill fungus to a manufactured fungus that lives within the plant to prevent other unwanted fungus hosting within it. Most readily available domestic fungicides come in chemical form.

As with all chemical products, there are discussions online both for and against the use of fungicides.  Chemical fungicides should always be used with caution as they are not something that should be sprayed abundantly over your plot. Nevertheless, if used correctly and in moderation fungicides can be beneficial for managing and preventing fungal attacks.

As with many lawn related ailments, an established good healthy lawn which is well maintained will be better equipped to deal with fungal attack. The first step to prevent disease in your lawn is therefore to ensure that it is as healthy as it can be. This should be done by regularly using a balanced, steady, slow release nutrition (such as Stripy Green fertiliser); cutting regularly at a good cutting height; aerating and removing thatch and scarifying. Other useful fungal prevention tips include; try not to walk on lawns when they are damp or wet as this can spread fungus; try not to boom and bust the lawn with nutrition as this stresses the grass and allows fungus to strike; always clear grass clippings as when left on top of the lawn, the clippings will rot and encourage fungus. It is also worth noting that grass breeders also use fungal resistance as part of their selection process for new varieties so by choosing turf or seed from suppliers that are using modern grass species you are one step closer to a disease free lawn.

Another benefit of using a fungicide on your lawn is that it will have a more even colour that is vibrant as fungicides can increase the greenness of the grass by aiding nutrition absorption. Additionally, one of the more prevalent grass fungal disease, fusarium, can often take hold after an application of nitrogen rich fertiliser. However, if a systemic fungicide has been applied, the active ingredient within the plant can prevent this fungal attack.

Chemical fungicides currently available, such as Bayer’s Lawn Disease Control, are much better at preventing the fungal attack from happening, rather than curing an existing disease. Once a fungal attack has already started and gotten a hold it will mean that you are already on the back foot in terms of treatment. Therefore, by incorporating the use of fungicides into an integrated maintenance programme for your lawn, fungal attacks can be kept at bay or even prevented.

The timing of fungicide application can be tricky as there are two main seasonal ‘hotspots’ for fungal attacks; the first is from May/June into July and the second is August/September.  By carefully timing the application of systemic fungicides (these are absorbed within the plant and remain active for approximately six weeks) you can prevent fungal attacks happening. Depending on the season, one application could take you through one of the ‘hotspots’, but as with anything horticultural, the weather plays a huge role in the timing and severity of fungal attacks. With warmer, damper conditions you get more severe and prolonged fungal attacks and you may need repeat applications.  There are now certain Apps and retailers where you can purchase ‘hotspot’ indicators which may help with timing of fungicide application.