Apple Harvest Time

Posted: January 12, 2012

Backyard orchardists are noticing a black sooty looking material on the surface of their apples as they harvest. It is a fungal disease which is appropriately named “sooty blotch”.

It is most prevalent in late summer and fall. Disease outbreaks are favored by extended periods of above-normal summer temperatures, combined with frequent rainfall and high humidity. Does that sound familiar? Another surface disease that is often found with sooty blotch is “fly speck”. A small patch of small black dots develops that, of course, looks like fly specks. Who thinks up these names? While these diseases make the surface of the fruit look unattractive, they can be rubbed off with a rag and dish detergent. If you use fungicides to protect your fruit trees, the fungicide Captan is recommended for control of sooty blotch and fly speck.

Cultural controls include the removal of alternate hosts such as brambles from the orchard and surrounding areas. Dormant-season and summer pruning that opens up the tree canopy and facilitates air movement and the drying of fruit after a rain period will help control these diseases. Thinning to separate the fruit clusters also will help prevent disease.

For more information contact your local extension office. In Lackawanna County call 570-963-6842 or email
John Esslinger, Extension Educator
Penn State Cooperative Extension