Investigating Black Jelly-Like Exudate on Weeping Apple Tree Branches

Possible Causes

A black, slimy, jelly-like substance on branches could be bacterial ooze from fire blight (Erwinia amylovora), though typically accompanied by other symptoms (wilted blossoms, shepherd's crook shoots, cankers). Alternatively, it may be a yeast/fungal growth on sap from wounds or insect feeding.

Diagnostic Questions

Is the substance sticky or sweet? Are leaves deformed or discolored? Is there new growth? Fire blight ooze appears after the disease is established. A certified arborist can sample the exudate for lab confirmation.

Immediate Steps

Prune out any dead or cankered wood well below affected areas, sterilizing tools. Avoid nitrogen fertilization. Monitor for further symptoms. If fire blight is confirmed, follow strict sanitation and copper spray protocols during dormancy.