Cherry Leaf Spot (Blumeriella jaapi) is a fungal infection that typically starts to form in the spring when temperatures are between 60-68 degrees Fahrenheit with rainfall and high humidity (Jones). The disease has been estimated to infect 80% of Eastern United States orchards and can reduce crop yields by nearly 100% (Grant).

Cherry Leaf Spot spreads by airborne spores that infect the bottom of leaves when it rains (Ellis).

Cherry Leaf Spot may often be identified by its dark spots on the top side and symmetric brown spots on the underside of the leaf. As the disease progresses, more spots will be produced and the leaf will eventually turn yellow and fall off the tree.

Cherry Leaf Spot is most active in the summer, but it starts to form in the spring (May). The leaves will begin to fall off throughout the growth season and will remain on the ground over the winter (Wise).

Cherry Leaf Spot has little risk until after bloom occurs. MSU Extension estimated bloom at 5/7/2020 and around a GDD of 320 at Base 42. Although, Cherry Leaf Spot becomes more infectious as the rainfall (wetting period) increases (East).

It is best to spray 100 gallons per acre with fungicide diluted in water. The label on the fungicide will tell you a maximum use rate per acre.

Fungicides that treat Cherry Leaf Spot most often have an active ingredient of myclobutanil or captan. For organic options, there is an active ingredient of copper (Grabowski).