Wikipedia
Cherry leaf spot is a fungal disease which infects cherries and plums. Sweet and sour cherries are susceptible to the disease; however leaf spot is much more prevalent in sour cherries. The variety of sour cherries that is the most susceptible are the English Morello cherries. This is considered a serious disease in the Midwest, New England states, and Canada. It has also been estimated to infect 80 percent of orchards in the Eastern states. It must be controlled yearly to avoid a significant loss of the crop. If not controlled properly, the disease can dramatically reduce yields by nearly 100 percent. The disease is also known as “yellow leaf” or “shothole disease” to cherry growers due to the characteristic yellowing leaves and shot holes present in the leaves upon severe infection.