Cherry trees normally shed all their leaves in autumn, over a few weeks, as days shorten and temperatures fall.1Cherrytimes. Autumn leaf fall of cherry trees Before letting go, the tree pulls useful material back out of its leaves, so a normal autumn drop is part of how it prepares for spring. Leaves falling in mid-summer are a different story, and usually mean the tree is under stress or attack, from drought, heat, disease, mites, soggy soil, or a lack of nitrogen.
The Normal Autumn Leaf Drop
The trigger is a combination of shortening days and falling autumn temperatures.2Cherrytimes. Autumn leaf fall of cherry trees Once the drop starts, it takes about 15 to 30 days to finish.3Cherrytimes. Autumn leaf fall of cherry trees By winter the tree is completely bare and enters its winter rest.4Cherrytimes. Autumn leaf fall of cherry trees
In a yard, a healthy drop looks fairly even. Leaves turn yellow, orange or red across the whole canopy rather than in patches, though the sunniest or most exposed side may turn a few days earlier. Healthy autumn leaves are colored but not spotted, curled or speckled.
Warm autumns can push the drop later, although exactly how sensitive flowering cherries are to autumn warmth is still uncertain.5PubMed Central. Predicting the Timing of Cherry Blossoms in Washington, DC and Mid-Atlantic States in Response to Climate Change Leaves hanging on into late autumn in a mild year are usually not a problem.
Timing also varies from tree to tree. A tree in a sheltered, warm spot, such as against a south-facing wall, feels the cold later and may hold its leaves longer than one in open ground. Young trees and well-watered trees often keep growing and stay green later. Different cherry varieties can drop a week or two apart, so a neighbor’s bare tree does not mean yours is in trouble. A hard early frost, on the other hand, can end the season abruptly and bring leaves down in a few days.
The calendar is the best way to separate autumn from trouble. A healthy drop happens once the season has clearly turned, so leaves falling in July or August are outside the normal pattern, however yellow they look. Leaves that fall while still mostly green, or that are covered in spots, holes or speckling, point to a problem and not to autumn.
Why Autumn Leaf Drop Matters for Next Year
In autumn, sweet cherry leaves lose up to about half their nitrogen.6HortScience. Foliar Applications of Urea Affect Nitrogen Reserves and Cold Acclimation of Sweet Cherries (Prunus avium L.) on Dwarfing Rootstocks Much of it moves into the short shoots that carry next year’s flowers, which gain up to about a quarter more nitrogen.7HortScience. Foliar Applications of Urea Affect Nitrogen Reserves and Cold Acclimation of Sweet Cherries (Prunus avium L.) on Dwarfing Rootstocks Stored sugars in the roots, branches and trunk build up mainly after harvest and peak around leaf fall.8cherrygrowers.org.au. The Effect of Pre-Harvest Tree Management on Postharvest Fruit Quality Leaves lost early in summer can’t finish this transfer, which leaves the tree with less stored energy for spring.
Fewer reserves can mean sparser blossom and a smaller fruit crop the next year. A single bad year rarely kills an established tree, but repeated early drop wears it down.
Picking yellowing leaves off a healthy tree doesn’t help it, because those leaves are still handing over nutrients. Let them fall on their own so the tree can finish the job. Clearing the fallen leaves afterward is a good idea only if the tree had spots or disease.
Early Leaf Drop From Cherry Leaf Spot
Cherry leaf spot is a fungal disease that can make cherry leaves drop early.9Lawnstarter. 7 Common Cherry Tree Diseases and How to Treat Them It is a serious disease especially of sour cherries.10Plant Pathology. Assessment of the inheritance of resistance and tolerance in cherry (Prunus sp.) to Blumeriella jaapii, the causal agent of cherry leaf spot Infected leaves develop yellowed and dead patches. The damage goes beyond what you see, because even the green parts of spotted leaves make far less food.11PubMed. Effects of cherry leaf spot on photosynthesis in tart cherry ‘Montmorency’ foliage
On your tree, leaf spot usually starts as small purple to brown spots on the upper surface of the leaves, often in early summer. The tissue around each spot turns yellow, and heavily spotted leaves then fall. In wet weather you may find pale fungal growth on the underside of a spot, which helps separate leaf spot from other causes. Outbreaks are worse after wet, humid springs, so a rainy season should make you look more closely.
A bacterial disease can look similar but behaves differently. It causes spots that fall out, leaving leaves looking shot full of holes, and these symptoms can appear as early as May.12Journal of Phytopathology. Evaluation of cherry cultivar susceptibility to bacterial canker and leaf spot disease
Several steps reduce leaf spot. The fungus survives winter on fallen leaves, so rake them up and remove them in autumn instead of leaving them under the tree. Prune to open the canopy so air moves through and leaves dry faster after rain. Water at the soil and not over the foliage, since wet leaves favor the fungus. If the disease keeps returning, ask a local extension service about fungicide timing, because the right timing depends on local conditions.
Early Leaf Drop From Spider Mites
Spider mites suck the contents out of leaf cells.13UC IPM. Cherry Spider Mites Damage begins as fine pale speckling on the leaves.14UC IPM. Cherry Spider Mites Leaves can then bronze or turn yellow and drop off, although leaf drop usually comes only with heavy infestations.15Pacific Northwest Pest Management Handbooks. Cherry-Spider mite16WSU Extension. Cherry: Spider mites
To check, hold a sheet of white paper under a branch and tap it, then watch for tiny specks that move, which are likely mites. Look at leaf undersides for fine webbing, which shows a well-established population. Mites do best in hot, dry, dusty conditions, so expect trouble in mid to late summer.
A strong spray of water from a hose can knock mite numbers down. Avoid broad-spectrum insecticides, which kill the predators that normally keep mites in check and can make outbreaks worse. Horticultural oils or insecticidal soaps are a lower-impact option if numbers are high.
Early Leaf Drop From Heat, Drought and Waterlogging
High heat and drought can make cherry leaves drop.17Lawnstarter. 7 Common Cherry Tree Diseases and How to Treat Them A tree short of water sheds leaves to conserve moisture, and this often shows up in late summer dry spells, around August.18ask.extension.org. Cause for early leaf drop flowering cherry tree
Too much water harms the tree too. Waterlogged soil makes cherry leaves lose their green color, yellow, age early and fall, and the tree makes less food as a result.19PubMed Central. Oxygenation alleviates waterlogging-caused damages to cherry rootstocks Some rootstocks cope far better; one plum-based rootstock showed no damage after 30 days of flooding.20Scientia Horticulturae. Physiological and morphological responses of Prunus species with different degree of tolerance to long-term root hypoxia
To work out which problem you have, dig a small hole near the edge of the canopy and feel the soil several inches down, since the surface can mislead. Dry, crumbly soil points to drought. Soggy soil with a sour smell points to waterlogging.
During dry spells, water deeply once or twice a week and not lightly every day, so water reaches the deeper roots. Mulch around the base to hold moisture, keeping it off the trunk so the bark stays dry. In heavy clay, improve drainage or plant on a raised spot so the roots don’t sit in water. If your site stays wet, ask a nursery about flood-tolerant rootstocks before planting a new tree.
Early Leaf Drop From Nitrogen Shortage
Nitrogen-short trees have small, narrow, pale green leaves and short shoots.21PubMed Central. Nitrogen Nutrition of Fruit Trees to Reconcile Productivity and Environmental Concerns Older leaves then turn yellowish orange to purplish and drop early.22PubMed Central. Nitrogen Nutrition of Fruit Trees to Reconcile Productivity and Environmental Concerns
Yellowing has many causes, so a soil test is the way to confirm a shortage before you fertilize. Feed in spring and not late summer, so new growth has time to harden before winter. Too much nitrogen produces soft, lush growth that invites disease, so follow label rates. Compost and mulch release nitrogen slowly and improve the soil over time. If a test shows enough nitrogen, look elsewhere, because roots that are waterlogged or stressed can’t take it up. Expect improvement to show in the next season’s growth, not within days of feeding.
How to Tell Which Problem Your Tree Has
- Spots, then yellowing and drop in early summer: likely leaf spot.
- Holes punched through leaves in spring: likely bacterial spot.23Journal of Phytopathology. Evaluation of cherry cultivar susceptibility to bacterial canker and leaf spot disease
- Fine speckling and bronzing in hot weather: likely spider mites.24Pacific Northwest Pest Management Handbooks. Cherry-Spider mite
- Wilting and crisp leaves in a dry spell: likely drought.25ask.extension.org. Cause for early leaf drop flowering cherry tree
- Yellowing with soggy soil: likely waterlogging.26PubMed Central. Oxygenation alleviates waterlogging-caused damages to cherry rootstocks
- Pale small leaves with old leaves falling first: likely nitrogen shortage.27PubMed Central. Nitrogen Nutrition of Fruit Trees to Reconcile Productivity and Environmental Concerns
If the cause is still unclear, bring a bagged sample of affected leaves to a local extension office or nursery, ideally including some that are only partly affected. Photograph the whole tree and take close-ups of both sides of the leaves. Note when the drop began and what the recent weather has been.