Other Leaf Diseases
Foliar Diseases of Hardwoods
Black Spot of Elm
Black spot of elm on an elm leaf in mid summer.
Black spot of elm on fallen leaves collected in autumn.
In the spring, perithecia are produced on the lower surfaces of fallen leaves where the black spots are located. The perithecia produce ascospores that infect new leaves.
Black fungal growth occurring on aphid exudates present on leaf surface.
Apple leaves showing symptoms caused be apple scab. Venturia inaequalis.
The fungus also attacks flowering crab apple trees. Leaves show symptoms like this in mid to late summer.
Aspen Twig Blight
Laboratory samples of leaf and shoot blight caused by Venturia tremulae (also has been called Venturia macularis). Brown to black lesions occur on leaves and the fungus progressively kills succulent, current year shoots.
Aspen twig blight in the field showing dieback of the current years shoots
Bur Oak Blight
Leaf veins turn brown and large necrotic lesions develop that are wedge-shaped and delimited by leaf veins. Fruiting structures, small black pustules, with conidia develop along leaf veins and on leaf petioles.