Why Is My Apricot Tree Dropping Leaves in Summer?

An apricot tree losing its leaves in July or August — well before the natural autumn leaf fall — is telling you it is under significant stress. Complete or near-complete summer defoliation weakens the tree substantially because the leaves are responsible for producing the carbohydrates the tree stores in wood and root tissue over summer, building the reserves needed for next year's blossom and early growth. Identifying why leaves are dropping and addressing it promptly limits the long-term damage.

Shot hole disease defoliation

Shot hole disease (Stigmina carpophila) causes infected leaves to develop so many holes by late summer that they become functionally useless and the tree sheds them early. The pattern progresses from the interior of the canopy outward, and affected leaves show the characteristic round holes before dropping. By midsummer in a severe year, the tree may be almost bare. Prevention the following year requires copper fungicide at bud burst and leaf fall, plus collection and removal of fallen leaves.

Bacterial canker leaf loss

Bacterial canker can cause early leaf yellowing and drop from branches where the vascular tissue has been damaged by the pathogen. Leaves on a canker-affected branch often turn yellow and drop while leaves on healthy branches remain green. Examine the bark of branches whose leaves are dropping — sunken, dead-barked canker lesions confirm the diagnosis.

Water stress

Severe drought stress, particularly in wall-trained trees in summer, causes the tree to shed leaves as a water conservation response. The leaves may wilt first, then yellow and drop. Wall-trained trees against brick walls in hot, sunny positions are particularly vulnerable. Water deeply and consistently and apply a thick mulch to retain soil moisture during dry periods.

Natural late-summer leaf thinning

Some early yellowing and shedding of the oldest leaves from the interior of the canopy in late August and September is part of the tree's normal seasonal cycle. If the leaf drop is limited, affects only the oldest leaves, and the rest of the tree remains green, this is not a cause for concern and does not require treatment.