Disease

How to Recognize

The first signs appear soon after flowering, usually in June. On the upper side of leaves, small reddish-brown dots appear, gradually enlarging and merging into irregularly shaped spots. On the underside of the leaf, a whitish-pink coating forms at these sites — this is the fungal sporulation (Krivko, 2014). Heavily affected leaves turn yellow and fall prematurely — sometimes the tree loses up to 80% of its foliage before fruit ripening. Fruits on such trees become smaller, watery, and tasteless. Spots on the fruit itself are rare, but they become deformed and fail to ripen.

The fungus overwinters on fallen infected leaves. In spring, with the onset of warm, humid weather, spores mature and are carried by wind and raindrops, infecting young leaves. Secondary infection occurs throughout the summer, so the disease progresses rapidly (Quero-García et al., 2017).

Control Measures

1. Fall leaf collection — mandatory and the most effective preventive measure. All fallen leaves should be raked and burned or buried deep in the soil. The fungus overwinters on them, and their removal sharply reduces the infection load for the next season (Mikheev and Revyakina, 2004).

2. Fungicide treatments. The first spraying is carried out before bud break with a 3% Bordeaux mixture solution (so-called "blue spraying") to destroy overwintering spores. The second — immediately after flowering (at the "green cone" stage or bud separation phase) with a 1% Bordeaux mixture or copper-based preparations (copper oxychloride). With severe disease development, treatments are repeated every 2–3 weeks, especially during rainy summers, alternating preparations from different groups (e.g., copper-containing and systemic fungicides) to avoid pathogen resistance (Webster, 1996; Long et al., 2021).

Important: the last treatment should be carried out no later than 20 days before harvest if the fruit is intended for fresh consumption.

3. Choosing resistant varieties. Some cherry and sweet cherry varieties are significantly less affected by coccomycosis. When establishing an orchard, give preference to zoned resistant varieties — their list can be obtained from local nurseries or specialists (Mikheev and Revyakina, 2004).

How to Recognize

In early spring, during flowering, affected flowers suddenly wilt, turn brown, and dry up, but do not fall off — they remain hanging on the tree, often together with adjacent leaves, creating a picture of a "scorched" branch. From the branches, the infection spreads to young shoots, causing them to wither. Wet cankers with gum exudation appear on the bark. Later, during fruit ripening, brown rapidly enlarging rot spots appear on them, covered with an ash-gray spore coating. Affected fruits mummify and remain hanging on the tree all winter, becoming a source of infection for the following year (Buckingham, 2010).

Disease Cycle

The fungus overwinters in mummified fruits and affected branches. In spring, in wet weather, spores are released and land on opening flowers. A few hours of wet weather at temperatures above +5 °C are sufficient for infection. Secondary spore spread occurs during rains, infecting ripening fruit (Quero-García et al., 2017).

Control Measures

1. Sanitary pruning. Early spring (before sap flow begins), cut out all dry, blackened, and damaged branches, taking 10–15 cm of healthy tissue, and burn them. Also remove mummified fruits remaining on the tree from the previous year (Mikheev and Revyakina, 2004).

2. Protective sprays. The first treatment is carried out before bud break with 3% Bordeaux mixture or iron sulfate solution (300 g per 10 L of water) to kill overwintering spores. The second — at the pink bud stage (immediately before flowering) and immediately after flowering — apply 1% Bordeaux mixture, copper oxychloride, or modern systemic fungicides (e.g., from the triazole group). In rainy years, a treatment 10–15 days after flowering is also necessary (Agustí, 2010; Webster, 1996).

3. Pest control. Insects (weevils, codling moths, wasps) damage the fruit skin, creating "entry points" for the fungus. Effective pest control also reduces the risk of moniliosis.

How to Recognize

In spring, small reddish-brown spots with a dark border appear on young leaves. After 1–2 weeks, the tissue in the center of the spot dies and falls out, forming through-holes of irregular shape — hence the name "shot hole disease." On shoots and branches, reddish spots appear, the bark cracks, and gum exudes. Affected fruits become covered with dark depressed spots, become deformed, and dry out. The disease develops especially strongly in warm, humid weather (Krivko, 2014).

The fungus overwinters as mycelium in affected one-year-old shoots and branches. In spring, spores are spread by raindrops and wind, infecting young leaves. Several generations of spores are produced per season, so without treatment the disease progresses rapidly.

Control Measures

1. Sanitary pruning. Remove and burn all affected shoots and branches. Treat gumming wounds (clean and apply garden wax).

2. Chemical protection. The same preparations as for moniliosis: autumn-spring spraying with 3% Bordeaux mixture, during the growing season — with 1% Bordeaux mixture or copper oxychloride. The first treatment is carried out before bud break, the second after flowering, and the third after 2–3 weeks if the disease is severe.

3. Removal of fallen leaves — mandatory, as fungal spores persist on them.

How to Recognize

The disease primarily affects fruit. During ripening, dull rounded spots appear on the skin, gradually pressing into the flesh. On the spots, concentric rings form — small dark bumps — fungal sporulation. In wet weather, these formations look like pink slimy pads; in dry weather, they dry into a pink crust. Often several such spots occur on one fruit. In dry weather, fruits mummify, giving the impression that they have "dried in the sun" (Quero-García et al., 2017).

The fungus overwinters in affected shoots and mummified fruits. Primary infection occurs during flowering and fruit growth, but symptoms appear only on ripening fruit — so-called latent infection.

Control Measures

1. Preventive sprays. The first treatment is carried out before flowering (at the pink bud stage) with contact or systemic fungicides, the second — immediately after flowering, the third — after 10–14 days (Mikheev and Revyakina, 2004; Borve et al., 2017). In rainy years, an additional treatment may be required before fruit ripening.

2. Removal of mummified fruits and affected branches. As with moniliosis, this is a mandatory autumn and spring procedure.

3. Choosing resistant varieties. Although resistant varieties to anthracnose are still few, relatively tolerant forms can be selected in some regions.

Powdery Mildew (Podosphaera clandestina)

This disease is more common on sweet cherries but can also affect sour cherries. It appears as a white powdery coating on leaves, young shoots, and fruit. Leaves become deformed, curl, and fall prematurely. Hot, dry weather with heavy dews favors disease development. Control: treatment with sulfur-containing preparations (e.g., colloidal sulfur) or modern fungicides during the growing season (Long et al., 2021; Webster, 1996).

Cytosporosis (Leucostoma spp.)

Pathogens of the genus Leucostoma affect bark and cambium, causing bark death, gum exudation, and branch dieback. Particularly dangerous for weakened, frost-damaged trees. Infection occurs through wounds and cracks. Control: cutting out and burning diseased branches, cleaning wounds and treating with garden wax, as well as creating optimal growing conditions — watering, fertilization, protection from sunburn (Quero-García et al., 2017; Webster, 1996).

Gray Mold (Botrytis cinerea)

Less common, but in wet years can affect flowers and fruit, especially with mechanical damage. A fluffy gray coating appears on fruit. Control — the same measures as for moniliosis, since these diseases develop under similar conditions (Borve et al., 2017; Buckingham, 2010).

Verticillium Wilt (Verticillium dahliae)

A soil-borne fungus that infects the root system, causing gradual wilting of branches and tree death. It appears in mid-summer: leaves on one branch turn yellow and dry, then the process spreads to the entire tree. Control is extremely difficult; the main prevention is not to plant cherries where Solanaceae (potatoes, tomatoes) or strawberries previously grew, which serve as pathogen reservoirs (Webster, 1996).

Root and Crown Rots (Phytophthora spp., Armillaria spp.)

Pathogenic fungi live in soil and infect the root collar and roots, especially on heavy, waterlogged soils. Symptoms: wilting, yellowing of leaves, death of young trees. Prevention — good drainage, planting on elevated sites, use of resistant rootstocks (Quero-García et al., 2017).

Bacterial Canker, or Bacterial Blight (Pseudomonas syringae)

This is perhaps the most serious bacterial disease of sweet and sour cherries worldwide. It can kill up to 75% of young trees under unfavorable conditions, especially in wet and cold regions. Losses of 10–20% in young orchards are considered typical (Long et al., 2021; Pulawska et al., 2017).

Symptoms appear on all above-ground parts:

• On the bark of trunks and branches — sunken, dark, dead areas of bark (cankers), from which amber or dark brown gum often oozes. Under the bark, the wood has orange-brown longitudinal streaks. If a canker girdles a branch, the part of the crown above it dies (Long et al., 2021; Pulawska et al., 2017).

• On buds and flowers — buds do not open, turn brown and die; flowers wilt, turn brown, but remain hanging on the tree — this resembles moniliosis but without the gray coating.

• On leaves — small angular dark brown spots appear, often with a yellowish border. In wet weather, spots enlarge, tissue dies, and the leaf becomes "tattered."

• On fruit — small dark sunken spots that can cover a significant part of the surface, making fruit unmarketable.

The bacterium lives on the surface of leaves and bark without causing symptoms until "entry points" appear: frost cracks, pruning wounds, insect or hail damage. Particularly dangerous are prolonged rains and fogs during flowering and in autumn during leaf fall (Pulawska et al., 2017).

1. Prevention is key. Plant cherry only on healthy, well-drained soils, avoid lowlands and stagnant air. Do not allow canopy crowding — ensure good air circulation.

2. Prune only in dry weather. The canker bacterium is active in wet weather. Prune trees during dry, preferably cool weather (but not in frost). Summer pruning in dry weather is significantly safer than winter pruning in wet regions. All pruning wounds should be smooth and covered with garden wax (Long et al., 2021; Webster, 1996).

3. Remove diseased branches. When cankers are found, cut the branch at least 15–20 cm below the visible lesion (into healthy tissue) and burn it. Disinfect tools after each cut (with alcohol or a 10% bleach solution).

4. Copper-based preparations (Bordeaux mixture, copper oxychloride) reduce bacterial numbers on the surface, but in some regions the bacterium has already developed copper resistance. In such cases, copper is not only useless but may worsen the disease by suppressing beneficial microorganisms. Check with your local plant protection service whether copper remains effective in your region (Long et al., 2021; Webster, 1996).

5. Protection against frost cracks. In autumn or late winter, whitewash trunks and the bases of scaffold branches with lime mixed with copper sulfate (as directed). This protects the bark from sunburn and cracking — the main "gateways" for the bacterium (Krivko, 2014).

6. Choosing resistant rootstocks and varieties. For example, the Colt rootstock is considered more resistant to bacterial canker than Gisela 6. Regina and Rainier varieties are generally less susceptible than Bing and Sweetheart. Check resistance with local nursery growers (Long et al., 2021).

Bacterial Leaf Spot (Xanthomonas arboricola pv. pruni)

This disease is more common on peach and plum, but can also affect cherries, especially in warm, humid regions. It appears as dark, angular, water-soaked spots on leaves, which then die and fall out, creating a "shot hole" appearance similar to clasterosporiosis, but the spots are usually more angular and confined by veins. Dark sunken spots form on fruit. The bacterium is spread by rain and wind (Pulawska et al., 2017).

• Mainly preventive: use of healthy planting material, removal and burning of affected leaves and branches, tool disinfection.
• During the growing season, copper-based preparations are used, but their effectiveness is moderate.
• In regions where this disease is widespread, it is better to choose relatively resistant varieties.

Crown Gall (Agrobacterium tumefaciens)

The bacterium lives in soil and enters through wounds on roots and the root collar, causing the formation of galls (tumors) — initially soft, then woody, with a rough surface. Galls disrupt the tree's water and nutrient supply. In nurseries, infected seedlings are discarded; in the orchard, the disease usually appears on young trees. Control — prevention: avoid damaging roots during planting and soil cultivation; do not plant cherries where crown gall previously occurred. A biological preparation based on the Agrobacterium radiobacter K84 strain protects roots when seedlings are soaked before planting (Pulawska et al., 2017; Webster, 1996).

Plum Pox Virus (PPV)

Sharka is one of the most dangerous viral diseases of stone fruits. It is less common on cherries than on plums or peaches, but in some regions (especially in Europe) it can cause serious damage (James et al., 2017). Symptoms: chlorotic spots and rings on leaves, leaf blade deformation, necrosis and rings on fruit, premature fruit drop. Transmitted by infected scions and aphids (non-persistently). No cure. The only measure — use certified healthy planting material; if found in the orchard — remove and burn infected trees. Many countries have sharka eradication programs.

Prunus Necrotic Ringspot Virus (PNRSV) and Prune Dwarf Virus (PDV)

These two viruses are widespread worldwide and often occur together. They are transmitted by pollen and seeds, as well as by aphids and thrips, and can cause a variety of symptoms: chlorotic rings and spots on leaves, "shot hole" (resembling fungal), leaf deformation, stunted growth, reduced yield, and poor fruit quality (James et al., 2017; Webster, 1996).

For example, with PNRSV infection, severe necrosis and "shothole" may be observed in the first year, then symptoms often disappear, but the virus remains. Prune dwarf virus can cause "blind" buds (without leaves) and narrow, deformed leaves. Both viruses reduce yield by 18–30%. No cure. Prevention: use of healthy planting material, removal of infected trees, especially before flowering (to prevent pollen-borne spread) (Webster, 1996).

Cherry Leaf Roll Virus (CLRV)

Found on cherries in Europe and North America. Causes yellowing and curling of leaves, shoot dieback, and can lead to tree death. Transmitted by pollen and seeds, as well as through infected material. Dangerous in mixed infections — for example, together with PDV causes enations (outgrowths) on the underside of leaves, and with PNRSV leads to rapid death (James et al., 2017). Same measures: healthy planting material and removal of infected trees.

Other Viruses

Many other viruses have been described on cherries, for example:

• Cherry Raspberry Leaf Virus (CRLV) — causes leaf deformation with characteristic outgrowths, reduces yield, transmitted by nematodes.
• Little Cherry Viruses 1 and 2 — fruits become smaller, paler, and tasteless; transmitted by mealybugs and graft material.
• Viruses of the genus Robigovirus — cause various necroses, mosaic, leaf deformation.

A general rule applies to all viruses: cannot be treated, prevention is mandatory. The main line of defense is purchasing seedlings from certified nurseries that test for major viruses.

X-Disease (Western X disease, Eastern X disease)

One of the most dangerous phytoplasma diseases of cherry in North America. Symptoms: fruit become smaller, bitter, poorly colored; leaves turn red and fall prematurely. On Mahaleb rootstock, the tree may die in the first year; on Mazzard rootstock, yield declines and the tree gradually dies. Vectors — leafhoppers. Reservoir — wild chokecherry (Prunus virginiana). Control: removal of diseased trees, elimination of wild chokecherry around the orchard, leafhopper control (in some states this is a mandatory program) (Webster, 1996; James et al., 2017).

European Stone Fruit Yellows (ESFY)

In Europe, this phytoplasma affects cherries, peaches, and plums. On cherries, it often runs latently or with mild symptoms (yellowing, leaf curling, reduced growth), but on some varieties it can cause death. Vector — the psyllid Cacopsylla pruni. Control is limited to using healthy planting material and removing diseased trees, as chemical control of the vector is often ineffective (James et al., 2017).

Aster Yellows (16SrI group)

A widespread phytoplasma affecting many plants. On cherries, it can cause dwarfing, yellowing, and witches' brooms. Transmitted by leafhoppers. No effective measures except removing diseased plants and controlling leafhoppers.

How a Gardener Can Distinguish Phytoplasma Disease from Others

Symptoms are often similar to viral or fungal diseases, but there are characteristic signs: witches' brooms (numerous thin shoots growing from one place), yellowing of veins or the entire leaf, sometimes proliferation (transformation of flowers into green leaflets). If you suspect phytoplasmosis, it is best to contact a diagnostic laboratory (such services are available in larger regions). No cure — the tree must be removed.

Infectious Causes

Gummosis almost always accompanies the following diseases:

• Bacterial canker (Pseudomonas syringae) — the most common "culprit" of profuse gummosis on trunks and scaffold branches. Cankers are always accompanied by gum exudation, especially in wet weather (Long et al., 2021; Pulawska et al., 2017).

• Cytosporosis (Leucostoma spp., Cytospora spp.) — the fungus affects the bark, causing its death and profuse gummosis, often with dark-colored gum (Quero-García et al., 2017; Webster, 1996).

• Clasterosporiosis (shot hole disease) — cracks and cankers form on shoots and branches, from which gum also oozes (Mikheev and Revyakina, 2004; Krivko, 2014).

• Moniliosis — when branches are affected (especially at the transition from flowers to shoots), gummosis is often observed.

• Root rots (Phytophthora, Armillaria) — when the root collar is affected, gum exudation is noticeable at the base of the trunk (Quero-García et al., 2017).

• Viral and phytoplasma diseases rarely cause direct gummosis but can weaken the tree, making it more susceptible to secondary infections that then cause gummosis.

Non-infectious (Abiotic) Causes

• Frost cracks and sunburn — sharp temperature fluctuations in winter and early spring lead to bark tissue rupture, and gum exudes from the cracks. The southern and southwestern sides of the trunk are particularly affected (Krivko, 2014).

• Mechanical damage — from garden tools, hail, animals, windthrow.

• Improper pruning — too large wounds, leaving stubs, bark tearing.

• Waterlogging or drought — stress from water imbalance weakens tissues and can trigger gummosis even without obvious pathogens.

• Excess nitrogen fertilizers — stimulates loose, succulent growth that is more prone to cracking and infection.

• Heavy clay soils — poor root aeration is also a stress factor.

1. Assess the Extent of Damage

• If gum is exuding from a small wound on a branch and the tree is generally healthy — you may try to save the branch.
• If a canker girdles the trunk or a large scaffold branch by more than 50% of its circumference — such a branch will most likely have to be removed. If the trunk is involved, the tree may die, and it is better to replace it, especially if it is a young tree.

2. Wound Cleaning

This is the main technique used for gummosis of any etiology (Mikheev and Revyakina, 2004; Krivko, 2014):

• With a sharp garden knife, clean the wound — remove all dead, cracked bark and gum down to healthy, light-colored wood. The wound edges should be smooth.
• Take 1–2 cm of healthy tissue around the perimeter.
• Disinfect the cleaned surface with a 1–3% solution of copper sulfate (or Bordeaux mixture). This suppresses pathogens on the surface.
• Allow the wound to dry for 1–2 hours, then cover with garden wax or a special wound-healing paste. This protects against new infections and prevents further tissue desiccation.

Important: do not cover a fresh, wet wound — rotting may occur under the wax. Wait until the surface dries.

3. Treat the Underlying Disease

If the cause of gummosis is bacterial canker or cytosporosis, cleaning alone is not enough:

• Bacterial canker — in addition to cleaning, perform systematic pruning of diseased branches (in dry weather), as well as copper treatments at recommended times (see section 3.1). In regions with copper-resistant bacteria, follow local recommendations; other permitted bactericides may be required (Long et al., 2021).
• Cytosporosis — wound cleaning and treatment, as well as strengthening the overall condition of the tree with watering and potassium-phosphorus fertilization (without excess nitrogen).

4. Strengthening the Tree

Any gummosis is a signal of stress. For recovery, it is necessary to:

• Provide regular watering during dry periods, but without waterlogging.
• Balance nutrition: avoid excess nitrogen; apply potassium and phosphorus fertilizers (potassium increases tissue resistance, phosphorus stimulates root formation).
• Mulch the root zone to retain moisture and improve soil structure.

Removal of Fallen Leaves

Fallen leaves are the main overwintering site for the coccomycosis pathogen. The fungus Blumeriella jaapii overwinters specifically on them, and in spring, spores disperse throughout the orchard, infecting young leaves. If leaves are left under the tree, infection accumulates year after year (Quero-García et al., 2017).

What to do:

• In autumn (or early spring, before bud break), thoroughly rake and remove all fallen leaves. The best method is to burn them (if permitted in your region) or bury them deep in the soil outside the orchard.
• Do not use diseased leaves for compost unless you are certain that the compost will decompose properly at high temperatures (above +60 °C), which kills spores.

Removal of Mummified Fruits and Diseased Branches

Mummified fruits (dry, blackened, hanging on the tree) are a source of moniliosis. Fungal spores persist in them throughout the winter and infect flowers the following spring. Diseased branches with cankers are a source of bacterial canker and cytosporosis (Mikheev and Revyakina, 2004; Long et al., 2021).

What to do:

• In autumn, after leaf fall, carefully inspect the tree and remove all mummified fruits and dry, blackened branches.
• Cut diseased branches with a margin of 10–15 cm of healthy tissue. Cover cut sites with garden wax (especially if the wound diameter exceeds 1 cm).
• Burn all collected material — do not leave it in the orchard or put it in compost.

Weed Control

Weeds can be reservoirs of viruses, bacteria, and fungi. For example, bedstraw is an intermediate host for the cherry aphid, which transmits viruses (Mikheev and Revyakina, 2004). Verticillium fungus affects many weed species and Solanaceous crops (Webster, 1996).

What to do:

• Regularly remove weeds in the root zones and between rows, especially in young orchards.
• Use mulching (sawdust, mown grass, bark) to suppress weeds and retain moisture.
• In commercial orchards, herbicides are used, but for an amateur garden, mechanical weeding and mulching suffice (Krivko, 2014).

Tool Disinfection

Pruning and grafting are the main routes of virus and bacteria transmission. One infected tool can carry infection from a diseased tree to dozens of healthy ones (Mikheev and Revyakina, 2004; Webster, 1996).

What to do:

• After working with each tree (especially if disease is suspected), wipe pruner or saw blades with alcohol, 10% bleach solution, or a special disinfectant.
• Between cuts on the same diseased tree, also disinfect the tool to avoid spreading infection within the canopy.
• Regularly sharpen tools — a sharp pruner leaves smooth wounds that heal faster.

Site Selection and Planting

Cherries are demanding about growing location. Mistakes made when establishing the orchard are almost impossible to correct later.

Rules for site selection:

• Sunny, wind-protected location. Cherries love light; in shade they bear less fruit and are more affected by fungal diseases.
• Good drainage. Cherries cannot tolerate water stagnation — roots rot and the tree dies. If the soil is heavy, clayey, plant on mounds or install drainage.
• Elevated areas. Avoid lowlands where cold air accumulates — there, spring frosts damage flowers, creating "entry points" for moniliosis and bacterial canker (Agustí, 2010).
• Soil pH — 6.0–6.8. On overly acidic soils (pH below 5.5), roots absorb nutrients poorly; on alkaline soils (above 8.0), chlorosis develops (Mandai et al., 2021).
• Do not plant cherries after Solanaceous crops (potatoes, tomatoes, peppers, eggplants) — they are reservoirs of Verticillium (Webster, 1996).

When planting:

• The root collar (graft union) should be 2–5 cm above ground level — burying it provokes gummosis and root rots.
• Do not add fresh manure or nitrogen fertilizers to the planting hole — they burn roots and stimulate weak, loose growth susceptible to disease.
• After planting, water thoroughly and mulch the root zone.

Watering

Cherries are sensitive to both lack and excess of moisture.

Watering rules:

• During dry periods be sure to water — especially in phases: after flowering (for fruit set), during fruit growth, and after harvest (for next year's flower bud formation).
• Do not overwater. Water stagnation at the roots provokes root rots and gummosis. Water infrequently but deeply, so that water penetrates the root zone (40–60 cm), not just the surface.
• Best method — drip irrigation or furrow irrigation (not overhead sprinkling), keeping leaves dry. Wet foliage promotes coccomycosis and other fungal diseases (Agustí, 2010).

Fertilization (Balanced Nutrition)

Excess nitrogen is one of the main causes of cherry weakening. Nitrogen causes rapid growth of succulent, tender shoots that are easily affected by diseases and, in winter, freeze, creating entry points for bacteria (Krivko, 2014; Webster, 1996).

Fertilization rules:

• Do not overfeed with nitrogen. Nitrogen fertilizers (urea, ammonium nitrate) should be applied only in spring, in moderate doses (e.g., 30–60 g/m² active ingredient for a mature tree). The second half of summer — no nitrogen!
• Potassium and phosphorus for resistance. Potassium increases tissue strength and winter hardiness; phosphorus stimulates root formation and fruit bud set. Apply potassium-phosphorus fertilizers in autumn, when digging the root zone.
• Organic matter — only well-rotted. Do not use fresh manure. Apply humus or compost once every 2–3 years, not close to the trunk, but under the crown projection, incorporating to a depth of 15–20 cm.
• Microelements. Deficiency of boron, zinc, or manganese reduces immunity. Apply foliar feeds with complex fertilizers containing microelements in spring and early summer.
• Leaf diagnostics. If you are unsure of the tree's needs, have leaf analysis done. This will help determine exactly which elements are lacking (or, conversely, in excess) (Mandai et al., 2021).

Pruning

Pruning is a most important preventive tool. A properly formed canopy is well lit and ventilated, meaning it dries faster after rains, reducing the risk of fungal infections (Agustí, 2010; Krivko, 2014).

Pruning rules for health:

• Prune in dry weather — moisture promotes infection of wounds by bacteria and fungal spores.
• Remove crowding branches, those growing into the canopy, crossing, dry, and diseased. The canopy should be "transparent" to air and light.
• Cover all wounds over 1 cm in diameter with garden wax — this protects against pathogen entry.
• Disinfect tools after working with diseased trees.
• Do not leave stubs — cut branches "to the collar" (at the base, to the ring of bark swelling) so the wound heals faster.

Root Zone Care

• Mulching. A layer of mulch (peat, humus, bark, mown grass) 5–8 cm thick suppresses weeds, retains moisture, and improves soil structure. Mulch should not touch the trunk to avoid rot at the root collar (Agustí, 2010).
• Periodic loosening (no deeper than 10–15 cm to avoid root damage) improves aeration.
• In autumn, after leaf fall, dig over the root zone to spade depth — this destroys overwintering stages of pests and fungal spores in the topsoil.

Resistance to Coccomycosis

Breeders have developed cherry varieties that are relatively resistant to coccomycosis. They vary by region — check with local nurseries.

Resistance to Moniliosis

Completely resistant varieties do not exist, but some are affected less severely. For sweet cherries, for example, Regina and Lapins have been noted as possibly more tolerant, although this strongly depends on weather conditions (Long et al., 2021).

Resistance to Bacterial Canker

Varieties and rootstocks differ significantly in susceptibility (Long et al., 2021):

• More susceptible: Bing variety, Gisela 6 rootstock.
• More resistant: Regina variety, Colt and MaxMa 14 rootstocks.
• In regions with high bacterial canker pressure, choose Colt or MaxMa 14 rootstocks and varieties that show the least susceptibility in your area.

Resistance to Viruses

Resistant varieties generally do not exist. The only protection is the use of certified healthy planting material. Nurseries that monitor phytosanitary status test seedlings for major viruses (PNRSV, PDV, CLRV, plum pox, and others) (James et al., 2017; Webster, 1996).

Rootstocks and Their Influence

Rootstock affects not only growth vigor but also disease resistance (Long et al., 2021; Mandai et al., 2021):

• Mahaleb (Prunus mahaleb) — winter-hardy but sensitive to root rots (Phytophthora) and bacterial canker on heavy soils.
• Mazzard (Prunus avium, F12/1) — less sensitive to root rots but more susceptible to viral diseases.
• Colt — more resistant to bacterial canker and root rots; good for wet regions.
• Gisela 5 and 6 — dwarf rootstocks, early-bearing, but sensitive to bacterial canker and require good care.
• Krymsk 5 — resistant to bacterial canker and winter-hardy, good for dense planting.

Important Caution

There is no variety resistant to all diseases. Resistance is often narrow (e.g., to coccomycosis, but not to moniliosis). Moreover, resistance may not manifest in all regions or under all weather conditions. Therefore, relying only on the variety is not enough — a combination of measures is needed (sanitation + agronomy + sensible treatments).

Microbiological Preparations (Biofungicides)

These are preparations containing live cultures of beneficial microorganisms that suppress the development of pathogenic fungi and bacteria. They work through several mechanisms: compete for nutrients on the plant surface, produce antibiotic substances, and stimulate the plant's own immunity (Borve et al., 2017; Webster, 1996).

Most well-known preparations:

• Fitosporin-M — based on the bacterium Bacillus subtilis. Effective against many fungal diseases (powdery mildew, coccomycosis, moniliosis). Applied both to soil (watering) and for spraying. It is advisable to start treatments in early spring, repeating every 10–14 days, especially after rains. Works well in tank mixes with growth regulators and microelements.

• Trichodermin — based on the fungus Trichoderma harzianum. Suppresses root rots and other soil-borne infections (Phytophthora, Armillaria, Verticillium), and is also effective against pathogens persisting in soil and plant debris (Quero-García et al., 2017). Applied to soil in spring and autumn (around root zones) or used for wound treatment (as a paste). Especially useful on heavy soils with waterlogging risk.

• Planriz — based on the bacterium Pseudomonas fluorescens. Suppresses root rots and a range of foliar fungal infections (including powdery mildew). Can be used for root treatment before planting and during the growing season.

• Baktofit — based on Bacillus subtilis and other strains. Effective against powdery mildew, moniliosis, coccomycosis. Notable for being usable even in cool weather (at +5 °C).

• Alirin-B, Gamair — preparations based on bacteria Bacillus subtilis and B. licheniformis. Suppress fungal and bacterial diseases, including bacterial canker (in initial stages). Used for spraying and watering.

Practical recommendations:

• Biofungicides are incompatible with chemical fungicides and copper-containing preparations — use them separately or with a 5–7 day interval.
• Spray in cloudy weather or in the evening — beneficial bacteria are sensitive to ultraviolet light.
• For effectiveness, contact of the preparation with the pathogen is necessary, so spray thoroughly, especially the underside of leaves.
• Biopreparations work preventively; once disease is established, their effectiveness is lower.

Biological Protection Against Bacterial Infections

Biological control is most effective against crown gall. A preparation based on the non-pathogenic strain of Agrobacterium radiobacter (strain K84, commercial names — Galltrol-A, Norbac 84C) protects seedling roots when soaked before planting. This strain produces the antibiotic agrocin 84, which suppresses pathogenic strains (Pulawska et al., 2017; Webster, 1996). However, in some countries the use of this strain is restricted due to the risk of plasmid transfer; the mutant strain K1026 is recommended instead.

Against bacterial canker (Pseudomonas syringae), biological preparations (e.g., based on strains of Bacillus subtilis, B. amyloliquefaciens) have so far shown only moderate effectiveness and are mainly used as a supplement to chemical or preventive measures (Pulawska et al., 2017).

Attracting Beneficial Insects

Although this topic relates more to pest protection, it indirectly helps in disease control: many insects (aphids, mealybugs, leafhoppers) are vectors of viruses and bacteria. Their natural enemies reduce vector numbers.

• Lady beetles and their larvae — effective aphid predators.
• Lacewings — also feed on aphids, thrips, mites.
• Parasitoid wasps (e.g., Aphidius) — parasitize aphids.

To attract them, plant nectar-producing plants near the cherry orchard (dill, phacelia, mustard, buckwheat) that bloom throughout the season and serve as shelter and food sources for beneficial insects (Buckingham, 2010).

Plant Infusions and Decoctions (Folk Remedies)

These are often used in amateur gardening as an alternative to chemicals, but it is important to understand their limitations. They act more as repellents or weak contact agents, but cannot cope with severe infection (Mikheev and Revyakina, 2004).

Examples:

• Ash infusion (fill 1/3 bucket of wood ash with 10 L of water, steep for 2 days, strain). Effective against aphids and to some extent powdery mildew. Apply at the beginning of infection, repeat after 5–7 days.
• Onion peel infusion (150–200 g peel per 10 L water, steep for 4–5 days) — against aphids and mites.
• Tobacco or shag infusion (400 g per 10 L hot water, steep for 2 days, add 40 g soap) — against aphids and small caterpillars.
• Wormwood decoction (half bucket fresh wormwood, fill with 10 L water, steep for a day, boil for 30 min, strain, dilute 1:1 with water, add 40 g soap) — against caterpillars and aphids.
• Mustard infusion (100 g dry mustard per 10 L hot water, steep for 2 days, dilute 1:1 with water) — against aphids, mites.

All plant decoctions are best used immediately after preparation, in the evening. Be sure to add soap (household, 40 g per 10 L) as a sticker — without it, the solution runs off the leaves.

Important limitation: no plant infusion treats fungal and bacterial diseases systemically. They only wash spores from the leaf surface and temporarily suppress development in the initial stages. With severe coccomycosis, moniliosis, or anthracnose, folk remedies are useless.

Groups of Fungicides and Their Purpose

Fungicides are divided into:

• Contact — do not penetrate plant tissues, act only on the surface, washed off by rain. More environmentally safe but require frequent applications (especially after rains). Examples: copper-containing preparations, sulfur, Bordeaux mixture.
• Systemic — penetrate tissues, spread through the vascular system, protect new growth. Longer-lasting, less dependent on rain. Examples: triazoles (difenoconazole, tebuconazole), strobilurins, anilinopyrimidines.
• Translaminar — penetrate the leaf but do not spread throughout the plant. Intermediate between contact and systemic.

Main preparations for cherry protection:

Treatment Schedule

Chemical protection of cherries is built around phenological stages (Agustí, 2010; Mikheev and Revyakina, 2004):

1. Dormant phase (before bud break, early spring) — "blue spraying" with 3% Bordeaux mixture or 4% urea solution (400 g per 10 L water) + copper sulfate to kill overwintering stages of fungi (coccomycosis, moniliosis, clasterosporiosis) and bacteria. Treat both the canopy and the soil in the root zone (Krivko, 2014).

2. "Green cone" (beginning of bud break) — if signs of coccomycosis or clasterosporiosis are found: spray with 1% Bordeaux mixture or copper oxychloride. If the weather is dry, this treatment can be skipped.

3. "Pink bud" stage (immediately before flowering) — treatment against moniliosis (flower protection) with a systemic preparation (Chorus, Topsin-M). This is one of the critical timings. Important: do not use copper in hot weather — burns may occur.

4. After flowering (petal fall) — treatment against coccomycosis (Skor, Chorus) and repeat against moniliosis (if flowering was wet and cold). Depending on the variety and weather, 1–2 more treatments may be needed at 10–14 day intervals.

5. Fruit growth stage — if there were outbreaks of coccomycosis or anthracnose in previous years, carry out preventive treatments with systemic fungicides (Skor, Strobi) or contact ones (Polyram). Interval — 10–14 days. Important: stop treatments 20 days before harvest.

6. After harvest — treatment against coccomycosis (in the south — the second wave of the disease) and cytosporosis (to protect trees weakened after fruiting). Use contact or systemic fungicides as directed.

Features of Chemical Application

Bordeaux mixture and copper:

• Copper-containing preparations are phytotoxic (can cause burns) in hot weather (above +25 °C) and on young leaves. Therefore, 3% solution is used only before bud break, and during the growing season — only 1% and only in cool weather.
• In regions where Pseudomonas syringae has developed copper resistance, copper treatments may be useless or even harmful (Long et al., 2021). Check local recommendations.

Alternation of preparations — a mandatory rule for systemic preparations to avoid resistance development in pathogens. Do not use the same preparation more than twice consecutively in a season. Alternate preparations from different chemical classes (e.g., Chorus → Skor → Strobi). This is a key principle of anti-resistance strategy (Long et al., 2021; Borve et al., 2017).

Safety precautions for chemical treatments (Buckingham, 2010):

• Work in protective clothing, rubber gloves, goggles, and a respirator.
• Spray in calm weather, in the morning or evening (when bees are not actively flying).
• Do not exceed the concentration of preparations.
• Strictly observe the waiting period (the time from treatment to harvest, indicated on the package). For most fungicides, this is 20–30 days.
• After work, wash your hands thoroughly and change clothes.

Use of chemical preparations in amateur gardens:

• In small gardens, 2–3 treatments are often sufficient for many fungal diseases (before flowering and after flowering + if necessary during fruit growth).
• Purchase preparations from specialized stores in small packages — for an amateur garden, 10–20 g or 10–20 mL per 5–10 L of water is usually enough.
• Never store dissolved preparations — use freshly prepared solution within a few hours.

Principles of Integrated Protection

1. Monitoring — regular orchard inspections for early disease detection. Inspect leaves from both sides; pay attention to fruit and bark. Use traps for insect vectors.

2. Economic threshold — the decision to use chemical preparations is made only when the disease or pest has reached a level that could cause economic damage. For example, detection of single coccomycosis spots is a reason for spraying if the weather is wet; if dry, you may wait.

3. Priority to non-chemical methods — first use prevention, proper agronomy, resistant varieties, biological preparations. Chemicals — only when there is a clear threat.

4. Selective use of chemicals — use the safest and most narrowly targeted preparations, in minimally effective doses, at optimal times.

5. Alternation of preparations with different mechanisms of action — to prevent resistance.

6. Preservation of beneficial organisms — avoid treatments during flowering; choose preparations that are gentle on bees and other entomophages.

Practical Algorithm for a Cherry Orchard

Spring (before bud break):

• Sanitary pruning: remove dry, diseased branches, mummified fruits.
• Removal of fallen leaves from the previous year.
• "Blue" spraying with 3% Bordeaux mixture or iron sulfate solution (to kill overwintering stages).
• Whitewashing of trunks to protect against sunburn.

Green cone – pink bud period:

• If signs of coccomycosis or clasterosporiosis are present — treatment with 1% Bordeaux mixture or copper oxychloride (if spring is wet).
• If there was severe moniliosis in the previous year — spray with Chorus or Topsin-M before flowering.

Flowering:

• Chemical treatments are not carried out — they are dangerous to bees. Treatment with biopreparations (Fitosporin) in the evening is permissible if there is a threat of moniliosis.

After flowering (first 2–3 weeks):

• First treatment against coccomycosis and moniliosis: systemic fungicide (Chorus, Skor, Strobi) + if necessary, insecticide against aphids and weevils.
• Second treatment — after 10–14 days, alternating the preparation. If the weather is dry and there are no signs of disease, the interval can be extended to 3 weeks.

Fruit growth period (until ripening):

• Monitoring for coccomycosis and anthracnose. In wet weather — treatment with contact or systemic fungicides, observing the waiting period (at least 20 days before harvest).
• Use of traps for monitoring vectors that transmit diseases.

After harvest:

• Treatment against coccomycosis (if needed) — especially in the south, where the second wave of the disease occurs in August-September.
• Prevention of cytosporosis and other fungi that affect trees weakened after fruiting.
• Fertilization (potassium + phosphorus) to improve winter hardiness.

Autumn:

• Removal of all fallen leaves and fruits.
• Final treatment (if necessary) — with 3% Bordeaux mixture after leaf fall (to kill overwintering spores).
• Mulching of the root zone (to retain moisture and protect roots from frost).

Organic Gardening and IPM

If you follow organic farming principles, your options during the growing season are limited:

• Before flowering: copper application (Bordeaux mixture) is permitted in organic farming but limited in the number of treatments and doses (no more than 3–4 kg of copper per hectare per year). Use only as a last resort.
• During the growing season: sulfur-containing preparations (colloidal sulfur), biopreparations (Fitosporin, Trichodermin), plant infusions are permitted.
• For an organic orchard, the following are especially important: selection of resistant varieties, proper agronomy, thorough sanitation, and creation of conditions for beneficial insects.

However, in years with high infection pressure, organic cherry growing in humid climates can be extremely challenging. In such cases, only local preventive measures and possibly abandoning susceptible varieties are possible.