Certified GKH Gardening Expert
This can happen for a few reasons. Cooler than normal temperatures will cause wind burn, which is very common. Fungal infection from overly wet conditions will also be common. Windburn will treat itself, but a fungal infection will need to be addressed. 1/4 normal dose of dolomitic lime in tandem with wettable sulfur will take care of a fungal infection, and is good to apply each year, anyways, as a preventative.