A Technical Report from The Bartlett Tree Research Laboratories 387
Tubakia leaf spot, also known as Actinopelte leaf spot, is a late season fungal disease that commonly attacks oaks, particularly those in the red oak group (black, red and pin oak). Tubakia has also been reported on chestnut, maple, elm, ash, hickory, tupelo, redbud, sassafras, sumac and sweetgum. Leaf symptoms consist of small to large, dark brown or reddish-brown spots that are circular to irregular in outline and may coalesce to form larger necrotic areas or blotches. This disease may be confused with Anthracnose, another leaf disease of oaks; however, symptoms of Tubakia typically develop late in the growing season when temperatures are warmer.