Flowering cherry trees (Prunus spp.) are desirable for their masses of light pink or white spring flowers. The Higan cherry (P. subhirtella), Yoshino cherry (P. x yedoensis) and the Japanese cherry (P. serrulata) are all popularly grown in the United States, according to Clemson University. Unfortunately these beautiful trees are susceptible to a number of common diseases.
Cherry Twisted Leaf
This disease is a virus but not much is known about how it spreads, according to Oregon State University. The leaves of cherry trees afflicted with this disease appear to be kinked or twisted. Sometimes, the leaves are deformed, small or do not develop properly. The virus spreads through the tree at a rapid pace, affecting every branch, and will also spread through an orchard. Once a tree is infected, the symptoms will appear each year with varying degrees of severity.
The only way to treat this disease is to remove and destroy the infected tree. Prevent this and other viral diseases by making sure you plant rootstock that is certified disease-free.
Phytophthora Root Rot
Most cases of root rot are caused by one of the many species of phytophthora fungi, according to Oregon State University. The fungi, which attack the roots of the tree, thrive in very wet, poor-draining soil. Cherry trees planted in well-draining soil or on hillsides rarely suffer from this disease.
As the disease progresses, the feeder roots of the tree are damaged or destroyed, causing an overall decline in the growth of the tree. Above the surface of the soil, the home gardener may notice the tree wilting and dying. Once symptoms are noticed, it may be too late to save the tree, although drenching the soil with fungicide may help trees that are showing minor symptoms.
This fungal disease (Podosphaera clandestina) affects the newly uncurling leaves of the tree. The spores overwinter on the tree or even on nearby dead leaves. Spring rains and winds release the spores, which land on the new leaves and begin to multiply, covering the leaves and the twigs with a fine layer of fungus that resembles powder. This fungus spreads rapidly, especially in warm, humid weather.
Prune infected shoots if they are isolated. Water at the soil level to avoid wetting the leaves and make sure the tree has plenty of room around it for air to circulate so that water is not left standing on the leaves after a rainstorm. Spray the tree with a systematic fungicide, one that does not contain copper, as this can adversely affect the fruit, according to Oregon State University, every year to prevent this and other fungal diseases from developing. Apply according to the directions on the package according to the size and age of your tree.
Cherry Leaf Spot
The fungus Blumeriella jaapii, which travels on air and water, causes this disease. Affected leaves develop asymmetrical spots, which can range in color from shades of brown to deep purple. In time, the spots grow more numerous and merge, killing the leaf from the center outward. The leaf may shrivel, turn yellow or brown, drop off the leaf prematurely or exhibit all of these symptoms.
Plenty of air circulation around the tree can help reduce the incidences of this disease. Rake up and destroy affected leaves so that the fungus does not overwinter in the soil. Treat the tree with systematic fungicidal treatment in the spring, before leaf out and throughout the summer.