Snow mold is a fungal disease that appears in the early spring as the snow melts; while usually not alarming, there are ways to treat and prevent it.
One of the easier to diseases to identify, Red Thread shows up often for lawns with low fertility. This means a good lawn fertilization program is the best treatment.
In the early stages of the disease you will notice spots that look like burns on the blades of the grass, then turns brown and looks dried out. The melting out phase begins as weather begins to get hot and dry and your lawn will have areas that look drought damaged.
Dollar Spot looks how it sounds, round patches about the size of a one dollar coin. However, the patches can blend together forming larger areas.
This lawn disease usually occurs when grass growth is slowing down. It can weaken the grass and cause other disease problems.