Necrotic leaf blotch on Golden Delicious apple leaves. Necrotic leaf blotch usually appears in late June or early July and is most severe in the latter part of the growing season. Mature leaves from the base to the center of upright, succulent, rapid-growing shoots are usually the only ones that show symptoms. Young, immature leaves on succulent shoots and mature or cluster leaves on fruiting wood are usually not affected. The effect of the disease varies among individual Golden Delicious trees, both from orchard to orchard and from tree to tree within the same orchard.
Defoliation can be severe.
Irregular brown blotches, usually 0.5 to 1.5 centimeters in diameter, suddenly appear on leaves. The blotches are usually restricted by the larger leaf veins. Many affected leaves turn yellow and drop all at once a few days after the necrotic blotches first appear. The most conspicuous symptom of necrotic leaf blotch is the large number of yellow leaves, on the tree and later on the ground, that suddenly appear during July and August. A distinctive characteristic of the disease is its appearance in two to four, or more, waves of these symptoms during certain periods that are scattered throughout the latter half of the growing season.