Red Thread

Red Thread is a fungal attack and appears as dead patches of grass. If you look closely you will see the pink fungus on the leaf. The best way of checking this is to pluck some grass from the lawn and look at it close up. Fortunately, it doesn't kill the grass and the cure is simple, just treat with granular or soluble iron. Red Thread spores reside in the soil and wait for the right damp conditions to develop. 

Fusarium, Dollar Spot and other fungal diseases

The photos show dollar spot and two fusarium attacks. These diseases can be controlled if caught at an early stage by applying Soluble Iron in a strong dilution (5kg per 50 litres of water). I had quite well developed fusarium last autumn which I treated with iron. It was a perfect cure and the grass fully recovered. My tip is to treat early and treat again if the problem returns. Iron is very low cost and avoids using a fungicide which is expensive and only available to buy if you have a pesticide certificate. The STRI now recommend Iron for this purpose. Dedicate is a product that kills fungal diseases and also provides some protection. It is listed on the Fungicide page of my shop.