Cherry Tree Diseases: What's Wrong With Your Cherry and How to Fix It

Cherry trees attract a different roster of diseases than apples or peaches. Some of them, like brown rot, are shared across all the stone fruits. Others, like cherry leaf spot and X-disease, are cherry-specific and require management strategies that don’t transfer from other species.

Before you can treat anything, you need to know which cherry you’re dealing with. Sweet cherries (Prunus avium: Bing, Rainier, Lapins, Stella) are more susceptible to bacterial canker and X-disease. Tart or sour cherries (Prunus cerasus: Montmorency, North Star) are more susceptible to cherry leaf spot. Three diseases hit both species without favoritism: black knot, brown rot, and Cytospora canker (the last one being the disease most likely to kill the tree outright if you prune it at the wrong time of year).

Here’s how to tell what you’re looking at, what to do about it, and which problems mean replacing the tree is the right call.

How to tell which disease you’re looking at

Match the most obvious symptom and jump to the section below.

• Small purple-to-brown spots on leaves that turn the leaf yellow, then drop early through summer: cherry leaf spot
• Tan or gray fuzzy spore tufts on rotting fruit, brown wilted blossoms in spring: brown rot
• Black, hard, warty galls swelling on branches: black knot
• Sunken bark with amber gum, black pinhead dots in wet weather: Cytospora canker
• Branch dieback, gummy oozing lesions on young trees, blossoms wilting in spring before any fruit forms: bacterial canker
• Small pale-pink misshapen fruit that never colors up properly, scattered limb decline year after year: X-disease (phytoplasma)

Most cherry diseases either launch at bloom or build their spore load during the previous growing season. Strong sanitation in fall, smart pruning in late winter, and the right cultivar choice solve most of these before they start.

Cherry leaf spot

Cherry leaf spot (Blumeriella jaapii) is the most common cherry disease in North America and the one that turns up first every year. It’s a fungal disease that hits both tart and sweet cherries, but tart cherries take the worst of it. According to the University of Minnesota Extension, “all tart cherry varieties are susceptible.”

What it looks like

Small purple-red spots appear on the upper leaf surface in early summer, about a quarter-inch across. As they age, the spots turn reddish-brown and develop a yellow halo around the edge. Heavy infections cause the spots to fall out, leaving a “shothole” appearance, and the whole leaf eventually yellows and drops.

The economic damage isn’t from the spots themselves but from the defoliation. A tree that loses most of its leaves by July can’t store enough carbohydrates to survive the winter. The next spring it leafs out weakly, fruits poorly, and is vulnerable to other diseases.

Why it happens

The fungus overwinters in fallen cherry leaves on the ground. First infections happen about two weeks after bloom, when ascospores from those leaves splash up onto new growth during rain. From there, secondary infections cycle through the canopy all summer long. A wet June or July can take a tree from healthy to half-defoliated in three weeks.

What to do about it

This is a sanitation-plus-spray disease. Skip either step and you’ll be fighting it every year.

• Rake every fallen cherry leaf in autumn. Compost them in a hot pile, or bag them for trash. Removing the leaf litter cuts next year’s primary spore source dramatically.
• Spray timing: a copper fungicide or chlorothalonil application two weeks after bloom (when leaves are fully unfolded) protects the new growth from primary infections. Repeat on label intervals through the growing season. One post-harvest application also reduces overwintering inoculum. Bonide Copper Fungicide is the home-garden choice that doesn’t carry the regulatory baggage of commercial fungicides.
• Open the canopy to dry the leaves faster after rain. An open-vase trained cherry resists leaf spot far better than a dense one.

How to keep it from coming back

Cultivar choice helps if you’re planting new. Among tart cherries, North Star tolerates leaf spot reasonably well, though no commercial tart cherry is fully resistant. For sweet cherries, the disease is rarely as severe in the first place, so cultivar matters less than sanitation.

Brown rot

Brown rot is the same disease on cherries as on peaches: caused by Monilinia fructicola and sometimes Monilinia laxa, with three distinct symptom phases. Our peach tree diseases guide covers the full brown rot cycle and treatment protocol. On cherry, the differences are:

• Sweet cherries crack easily in rain near harvest, and brown rot bombs through cracked fruit overnight.
• The blossom blight phase is often more severe on cherry than on peach, especially in the Pacific Northwest where M. laxa dominates.
• Mummified cherries are smaller and harder to spot than peach mummies, so the winter cleanup is more tedious.

What it looks like

• Blossom blight: blossoms collapse, turn brown, and hang on the tree instead of falling. A clear gum bead often forms at the spur.
• Twig dieback: the small fruiting spur behind the blighted blossoms dies back, leaving dead tissue that becomes next year’s overwintering site.
• Fruit rot: a brown spot expands within days of appearing, often with tan or gray powdery spore tufts. The fruit shrivels into a hard mummy.

What to do about it

The protocol mirrors the peach approach. Spray at full bloom, repeat every 10-14 days through fruit development, tighten to 7-day intervals as fruit colors up. Remove every mummified cherry from tree and ground in winter. Prune out twig dieback with sterilized Felco F2 Bypass Pruners in late winter.

On sweet cherries specifically, the harvest-window control is the difference between losing 5% and losing 50% of the crop. If a heavy rain hits within a week of harvest, get the fruit off the tree, even at slight underripe, to keep brown rot from exploding.

Black knot

Black knot (Apiosporina morbosa, formerly Dibotryon morbosum) is one of the easiest tree diseases to identify on sight: hard, black, warty galls growing on the branches. It hits plums, cherries, and chokecherries hard, and once a neighborhood has it, you cannot fully eliminate it because every wild Prunus in a half-mile radius is a spore reservoir.

What it looks like

In year one, look for swollen olive-green areas on small branches, often missed because they look like normal growth oddities. By year two, the swelling has matured into a black, hard, distinctly knobby gall, often 1-6 inches long. The galls release spores from spring through early summer, infecting that year’s new shoots, which won’t show symptoms until the following year.

Why it happens

The fungus exists in a sleeper-to-sleeper cycle. First-year infections grow internally for months before showing any visible swelling. By the time you see the obvious black knot, the tree has been infected for a year or more. The U Minnesota Extension notes that infections can occur during wet periods as short as 6 hours during the active spring sporulation window.

What to do about it

This is a winter pruning disease. Late winter, before bud break, is the only practical control window.

• Cut at least 4-6 inches below every visible knot, into clean wood. The fungus grows beyond the visible gall, often 4 inches or more, so a cut right at the knot edge leaves the disease behind. Some sources recommend 6-8 inches for safety.
• Sterilize between cuts with 70% alcohol or 10% bleach. The blade carries spores from one branch to the next.
• Use anvil pruners on dry, dead galls: Felco F31 Anvil Pruners handle the hard woody knots cleanly where bypass pruners would crush and tear.
• Burn or bag the prunings. Don’t compost. Spores survive composting.
• Plan two pruning passes the first year. Knots you missed (the small first-year swellings) will show up obvious by the next winter.
• Remove wild plum or chokecherry within 500 feet if you have any access to do so. Wild Prunus are spore factories that re-infect your cultivated trees every spring.

Chemical control is rarely worth pursuing on backyard trees. Captan or chlorothalonil applied during the spring spore-release window can reduce new infections, but you’d need a sprayer, accurate timing, and multiple applications. The pruning approach handles 90% of cases on a manageable backyard tree.

How to keep it from coming back

Cultivar choice helps. Among plums, Damson and President show better resistance than European prune-types. Among cherries, sweet cherries are less susceptible than tart cherries and chokecherries. Sour cherry cultivars vary widely. If you’re starting fresh in a black-knot-heavy neighborhood, consider switching to a stone fruit other than plum or cherry.

Cytospora canker

Cytospora canker on cherry is the same disease as on peach: caused by Cytospora leucostoma, entering through pruning cuts and winter-injured bark, no chemical cure once established. The full management protocol is in our peach tree diseases guide, and the rules transfer directly to cherry:

• Prune in dry late-winter weather only (February or early March)
• Cut 12 inches below the canker into clean wood
• Sterilize tools between cuts
• Whitewash trunks of young cherries to prevent sunscald entry points
• Whitewashed trunks reflect heat and prevent the south-side bark splitting that gives Cytospora its main entry route

One difference worth noting: cherry trees are more sensitive to the timing rule than peaches. A fall-pruned cherry is at much higher risk for Cytospora infection than a fall-pruned apple. Never prune cherries in October, November, or December. Wait for February.

Bacterial canker

Bacterial canker (Pseudomonas syringae) is the disease that kills young cherry trees. It’s worst in the first 5-7 years after planting, hits sweet cherries harder than tart cherries, and produces a symptom complex that overlaps confusingly with both Cytospora canker and brown rot blossom blight.

What it looks like

Multiple symptoms, often appearing in combination:

• Blossom blast: blossoms wilt and die during bloom, often blackened at the base, without producing fruit. Looks like brown rot but happens earlier and in cool wet weather rather than warm wet weather.
• Gummy lesions: amber gum oozing from sunken dark patches on the trunk or scaffold limbs. Often multiple small cankers rather than one large one, distinguishing it from Cytospora.
• Leaf spotting and “shothole”: small angular dark spots on leaves, sometimes falling out to leave holes. Less prominent than the bark symptoms.
• Dead buds and dieback: buds that fail to open in spring, often with visible gum at the base.
• Sour-smelling cambium: scrape the bark under a fresh canker. Bacterial canker has a noticeably sour or fermented smell that Cytospora doesn’t.

Why it happens

The bacterium overwinters in cankers and on healthy bud surfaces. Wet, cool spring weather lets the bacteria multiply and infect through natural openings (lenticels, leaf scars) and any wounds. Young trees are more vulnerable because their bark is thinner and their wound response is slower than mature trees.

Sites with poor drainage, sandy soil, or exposure to cold winter winds dramatically increase the risk. Trees stressed by drought in late summer don’t cold-harden properly and become highly susceptible the following spring.

What to do about it

Once a tree has bacterial canker, the goal is to manage it down rather than cure it. There is no eradication.

• Fall copper application: Oregon research cited by university extensions shows that a 10% lime sulfur or copper application at leaf drop in fall reduces bacterial populations significantly heading into the next spring. This is the single highest-impact management step on a young cherry.
• Withhold late-summer water: gradually reduce irrigation in August and September so the tree hardens off and cold-tolerates better. A drought-stressed tree in late summer cold-hardens better than a lush late-summer tree.
• Don’t interplant new cherries with old ones. Existing trees are the bacterial reservoir. Plant new cherries at least 50 feet from any existing stone fruit with a canker history.
• Control grass weeds around the tree. Pseudomonas populations build up on grass and splash to the trunk during rain. Maintain a clean mulched ring at least 4 feet wide around young trees.
• Prune in February or March only, with sterilized blades, in dry weather. Same protocol as Cytospora.
• Plant resistant rootstocks: Mazzard rootstock (Prunus avium seedling) is more bacterial-canker-tolerant than the precocious dwarfing rootstocks like Gisela. The trade-off is a much larger tree.

How to keep it from coming back

Site selection at planting prevents most bacterial canker. Well-drained soil, full sun, protected from cold winter winds, and away from older cherry trees. Our guide to where cherry trees grow best covers the climate and soil conditions that minimize disease pressure.

X-disease (phytoplasma)

X-disease is the cherry disease nobody wants to find on their tree. It’s caused by a phytoplasma (a bacterium-like organism without a cell wall), and there is no cure. The Pacific Northwest tree fruit industry treats it as a quarantine-level threat. Backyard growers should know about it because removing infected trees promptly is the only thing that protects neighboring cherries.

What it looks like

X-disease symptoms vary by strain and by location, which makes it tricky to diagnose without lab confirmation. Common signs:

• Small, pale, misshapen fruit that don’t color up at harvest. Often pink rather than deep red on sweet cherries.
• Leathery or pointed fruit shape rather than the normal round shape.
• Scattered limb decline: one limb declines this year, another the next, while the rest of the tree looks fine.
• Premature leaf drop in some strains.
• Bunchy growth with shortened internodes on affected limbs.

The Pacific Northwest strain often produces fruit symptoms only, with no leaf symptoms or stunting, which makes it harder to spot before fruit develops.

Why it happens

X-disease is spread by leafhoppers (Colladonus geminatus and C. reductus are the main vectors in the West). The leafhoppers pick up the phytoplasma when feeding on infected trees or on wild alternative hosts (chokecherry, bitter cherry), then transmit it during feeding on healthy trees. The phytoplasma can also move through grafting and through nursery stock, which is why certified disease-free planting material matters.

What to do about it

There is no chemical or pruning fix.

• Remove infected trees promptly. Per WSU Tree Fruit X-disease management, the only effective control is identifying and removing infected trees while leafhopper activity is high enough to spread the disease. Tag confirmed infected trees, treat with insecticide to kill resident leafhoppers, then remove the tree within a few weeks.
• Plant disease-free stock. Any new cherry should come from a nursery that certifies its scion wood and rootstock as virus and phytoplasma free.
• Remove alternative hosts. Chokecherry, bitter cherry, and wild plum within a 500-foot radius are leafhopper reservoirs and X-disease hosts. Removal of these alternative hosts is part of the standard PNW orchard management protocol.
• Leafhopper control. Insecticide applications targeting leafhoppers from July through October reduce vector populations. For backyard growers, this is rarely a primary strategy, but it’s part of commercial protocols.

How to keep it from coming back

The geographic distribution of X-disease is shifting. Historically a Pacific Northwest problem, the phytoplasma has now been confirmed in the northern San Joaquin Valley of California. For homeowners in cherry-growing regions, the practical step is to source new trees from certified nurseries and report suspect symptoms to your county extension agent for confirmation. Lab testing through a university plant diagnostic clinic runs $30-75 and gives you a definitive answer.

Sweet cherry vs tart cherry: disease susceptibility cheat sheet

The two cherry species differ enough in disease vulnerability that the right tree for your yard depends on which diseases are common locally.

Sweet cherries (Prunus avium: Bing, Rainier, Lapins, Stella, Black Tartarian):

• Higher susceptibility to bacterial canker
• Higher susceptibility to brown rot, especially in cracked fruit
• Lower susceptibility to cherry leaf spot
• Higher susceptibility to X-disease
• Crack easily in rain near harvest

Tart cherries (Prunus cerasus: Montmorency, North Star, Meteor):

• Higher susceptibility to cherry leaf spot
• More winter-hardy
• Lower susceptibility to bacterial canker
• Self-fertile (only one tree needed)
• Less crack-prone but smaller fruit

If you live in the upper Midwest or Northeast with cold winters and wet summers, tart cherries are the safer bet. If you live in California, the dry-summer western states, or the Carolinas, sweet cherries handle the disease pressure better, with the major exception of harvest-time rain that triggers brown rot.

When to call an arborist

Three situations warrant a professional visit. First, a young cherry with progressive bark canker that may be bacterial canker, where confirmation matters because the long-term prognosis is different from Cytospora. Second, a cherry with X-disease symptoms (small misshapen fruit, scattered limb decline), where lab testing and rapid removal protect the rest of your stone fruit. Third, an established backyard cherry over 20 years old with multiple cankers or major dieback, where deciding between heroic surgery and replacement matters financially.

An ISA-certified arborist consultation runs $75-200 in most US markets. Find one through the Trees Are Good arborist locator or read our guide to what an arborist does before you call.

If the tree is past saving, tree removal on a mature cherry typically runs $400-1,500 depending on access and what’s around it.

Prevention checklist

Seven habits handle most cherry disease problems:

• Site selection first. Well-drained soil, full sun, protected from cold winter winds, away from older cherry trees. Most disease problems trace back to a poor site choice that no spray schedule can fix.
• Buy certified disease-free trees from a reputable nursery. Free X-disease and bacterial canker bonuses don’t exist.
• Rake every fallen leaf in autumn. Single highest-leverage cherry leaf spot prevention. Twenty minutes a year.
• Two dormant copper sprays: one at leaf drop (October-November), one in late winter just before bud swell. Knocks back bacterial canker, brown rot, and leaf spot inoculum simultaneously.
• Prune in February or March only. Never in fall, never in summer except for fire-blight-like emergency cuts on infected wood. Always in dry weather, always with sterilized tools.
• Remove mummified fruit every winter. Same as peach. Single highest-leverage brown rot control.
• Walk the tree every February with pruners. Cut out any black knot, any visible canker, any dead wood. Two passes the first year (some knots are too small to spot on the first pass).

For nutrient timing through the season that supports tree vigor without overstimulating soft late-season growth, see this fruit tree fertilizing guide on mklibrary.com. For broader fungal disease patterns across the rest of your yard, see our tree fungus guide. If you also grow apples or peaches, the apple tree diseases and peach tree diseases guides cover the related problems on those species (brown rot, Cytospora canker, and bacterial canker cross between all the stone fruits).

Frequently asked questions

What is the most common cherry tree disease?

Cherry leaf spot is the most common. Purple-brown spots on leaves through summer, premature defoliation, weakened tree the following year. Tart cherries get it worst. Brown rot is the most economically damaging because it ruins the crop, and bacterial canker is the most likely to kill a young cherry tree before it produces.

Can I save a cherry tree with bacterial canker?

Sometimes. The strategy is management, not cure. Reduce bacterial populations with fall copper sprays, prune affected wood in dry late-winter weather, control grass weeds, and harden the tree off properly in late summer. Many trees stabilize and live productively for years with bacterial canker present. Others decline and die within 5-7 years despite best efforts.

What’s the difference between bacterial canker and Cytospora canker?

Both produce amber gum and bark damage. Bacterial canker (Pseudomonas syringae) tends to show up in young cherries (5-7 years old) after wet cool spring weather, with multiple smaller cankers, sour-smelling cambium under the bark, and additional symptoms like blossom blast and dead buds. Cytospora canker (Cytospora leucostoma) shows up on sun-injured or pruning-wounded bark of any age, with single larger cankers, often producing pinhead-sized black fruiting structures with reddish spore tendrils in wet weather. Both require the same pruning protocol (late winter, 12 inches below canker, sterilized tools) but bacterial canker also benefits from fall copper sprays while Cytospora doesn’t.

Will black knot kill my cherry tree?

Slowly. Each black knot girdles the branch it grows on, killing the wood above it. A heavily infected tree gradually loses its productive scaffold limbs over 3-5 years and stops producing meaningfully. Aggressive winter pruning (cut 4-6 inches below every knot) keeps the tree alive and productive for decades, but the disease cannot be eradicated once it’s established in a neighborhood because wild Prunus trees re-infect every spring.

Are cherry tree diseases contagious to other trees?

Some. Brown rot crosses all stone fruits (cherry, peach, plum, apricot, nectarine). Black knot crosses cherries, plums, and chokecherries. Cytospora canker can move between cherry, peach, and apricot. Bacterial canker hits all stone fruits but rarely apples or pears. X-disease infects cherries, peaches, and some ornamental Prunus. If you grow multiple stone fruits, treat them as one disease system: same sanitation, same spray schedule, same pruning protocol.

Should I plant a cherry tree if my neighbor has black knot?

Plant tart cherry instead of sweet. Sour cherries handle black knot pressure better than sweets, and most home growers don’t notice the fruit yield differences until they’ve had the tree for years. The alternative is to plant a different stone fruit (peach, apricot) that black knot doesn’t infect. The third option, removing the neighbor’s infected wild cherry, is the orchardist’s preferred solution but rarely socially possible.

When is the best time to spray a cherry tree?

Two anchor sprays handle most disease pressure: one at leaf drop in October or November (knocks back bacterial canker and brown rot inoculum), and one in late winter at bud swell (handles leaf spot primary inoculum). Add a third spray two weeks after bloom for active leaf spot control on susceptible tart cherry varieties. More than three home-garden applications per year is rarely worth the time or material cost.