Knowledgebase
Fungus on Black Gold cherry tree fruit #563729
Asked May 22, 2019, 9:26 PM EDT
Montgomery County Maryland
Expert Response
It's difficult to confirm a brown rot diagnosis based on the photos submitted but it is a likely cause of the symptoms this time of year, especially based on plentiful rain and sufficiently warm temperatures.
Brown rot is a common, destructive fungal disease that makes growing stone fruit a challenge for Maryland homeowners. Sanitation and properly timed fungicide sprays help to combat the disease. The fungus overwinters in twig cankers and in mummified fruit that is left hanging on the tree or has dropped to the ground. So, pick off and dispose of infected fruit (and fruit stems) from the tree and rake up any that has fallen around the tree. Apply labeled fungicides when the blooms are between 5-10% open, at full bloom, and about 2 weeks prior to harvest. It is best to apply fungicides before a rain event is predicted instead of waiting until after. Additional cover sprays will be necessary if we are experiencing a cool, wet spring and summer. Rotating fungicides helps to reduce the fungus from becoming resistant to the preventative sprays.
Fungicides available to home gardeners can prevent but not cure infections. Organic fungicides like sulfur and copper can be somewhat effective but may damage new spring growth.
Information on brown rot:
https://extension.psu.edu/stone-fruit-disease-brown-rot
https://extension.umd.edu/hgic/topics/diseases-stone-fruit
Spray schedule from VA Tech (scroll down to stone fruit):
https://www.pubs.ext.vt.edu/content/dam/pubs_ext_vt_edu/456/456-018/ENTO-289C.pdf
Jon