This disease, caused by the fungus Taphrina caerulescens (a relative of the peach leaf curl fungus) is quite noticeable this late spring and into summer on a range of oak species. The fungus overwinters in infested buds and twigs and causes infection during moist periods in the spring as leaves emerge. On upper leaf surfaces the "blister-like" somewhat raised spots are greenish to yellow-green, eventually turning brown. On lower leaf surfaces these blistered areas appear as depressions in the leaves. Damage is typically not severe and controls (which to be effective would have to be applied in spring as leaves emerge) are generally not recommended. Some leaf drop may occur and releafing is common in such situations.

The maple tar spot fungi (Rhytisma acerinum and R. punctatum) cause black spots on leaves of their silver maple and Norway maple hosts. The spots start out as greenish-yellow spots and that is what we are seeing now. Eventually the black "tar-like" stroma of the fungus become prominent as we move into late summer and fall. With R. acerinum the tar-like spots may be as much as 1/2" across, but with R. punctatum there are clusters of much smaller "punctuated" tarry spots.

Considerable spotting, leaf yellowing, and leaf drop can occur, especially in wet years and in areas with poor air movement, Fortunately, much of the leaf drop tends to occur in August and September after much of the critical photosynthetic food production in the plant leaves has already occurred for the season. Thus, as Wayne Sinclair of Cornell University wrote, "Tar spot of maple is one of the most spectacular - and least damaging - diseases of maple." The fungus overwinters on fallen leaves, producing fruiting bodies which release spores to new foliage the next spring, so raking up affected leaves can help break the disease cycle from year to year.

This fungal leaf spot disease (Blumariella jaapii), formerly known as Coccomyces leaf spot of cherry, was quite common on wild cherries this spring and summer and is a major problem for edible cherry growers who have regular fungicide spray programs for this disease. Symptoms involve development of purplish leaf spots with necrotic brown centers, leaf shot-holing weeks later where leaf tissue in the affected lesions drops out, and leaf drop associated with yellow, orange, pink-red and brown leaves. Signs of the pathogen can often be seen as masses of spores oozing from the lower leaf surfaces.

For a few backyard or naturalized wild cherry trees, cleaning up fallen leaves in fall and planting in areas with good air movement are helpful. For those controlling fruiting or ornamental cherries with fungicides, sprays must be targeted for primary infections in spring during leaf emergence and for secondary infections occurring throughout the season. Labeled products that include fungicides such as propiconazole , myclobutanil or mancozeb + thiophanate methyl are used in spray programs, but again this is a control program that needs to start early.