University of Maryland Extension

Ornamental Fruit Trees: Preventing, Diagnosing, and Managing Problems

tree-flowering
Flowering crabapple (Malus ‘Camelot’). Photo: Dow Gardens, Bugwood.org

Key Points

  • Ornamental flowering fruit trees include cherry, plum, peach, apricot, hawthorn, crabapple, and serviceberry. All of these belong to the rose family of plants and have similar characteristics. 

  • These are attractive trees for Maryland landscapes, but they are subject to problems associated with insect pests, diseases, and weather extremes.

  • Most diseases are favored by wet seasons. Pest problems tend to be worse in areas where there are a significant number of active or abandoned orchards nearby. 

  • A large number of the problems observed by gardeners are not caused by pests or diseases. Abiotic problems may include: drought, excessive rainfall, weather extremes, low sunlight, compacted soil; planting too deeply; applying too much mulch; and/or root damage from cultivation. 

  • To establish and maintain ornamental fruit trees successfully, refer to information on:

  • The diagnostic chart below lists the symptoms of the most common problems and their management options.

Selecting Ornamental Fruit Trees

  • Make sure the species or varieties you select are well adapted to soil, water, light, heat, wind, and other prevailing conditions where they will be planted.

  • There are ornamental fruit trees that are native to Maryland including black cherry (Prunus serotina), serviceberry (Amelanchier canadensis), American wild plum (Prunus americana), and crabapple (Malus coronaria). Prunus and Malus species are especially valuable to native wildlife; they support high numbers of native butterfly and moth species (Tallamy, 2007). The caterpillars of these insects are essential food for young birds (Narango, et.al., 2018).

  • Select varieties that have resistance to diseases and pests. 

  • Stone fruits (cherries, peaches, plums, apricots) tend to have shorter lives than pome fruits (apples and pears). The average life of a peach tree, for example, is 12 to 15 years.

  • Avoid planting invasive plants such as ‘Bradford’ pears

Anticipating and Preventing Problems

  • Anything that stresses an ornamental fruit tree may directly injure a tree and encourage insect pests (especially borers) and disease problems. Stressors include drought, physical damage to the trunk, compacted or poorly drained soil, defoliation, winter damage, or poor planting.

  • Use an Integrated Pest Management (IPM) approach to monitor your tree(s) regularly for symptoms and take recommended action steps to manage problems early.

  • Keep weeds down around your fruit tree plantings to remove favorable habitats for pests.

  • Do not apply mulch too deeply. Mulch should be no more than 2-3” deep and keep it 6” away from the base of the trunk to prevent vole damage, borer problems, and trunk diseases. 

  • Prune out water sprouts and root suckers.

Protecting Trees From Wildlife and Mechanical Damage 

  • Ornamental flowering fruit trees may need protection from deer. Use hardware cloth to loosely enclose the trunks of trees vulnerable to deer feeding. Where deer pressure is heavy, try rotating various commercial repellents. Hanging small cakes of deodorant soap from branches may also be helpful.

  • Protect young trees from vole damage by surrounding the lower trunk with hardware cloth, which should extend 2-3 inches below soil level.

  • Protect trees from lawn mower and string trimmer damage. Place a 2-3” layer of mulch in a wide circle around the trunk to eliminate the need for close trimming of unwanted grass. Keep the mulch 6” away from the trunk.

Pruning and Training

  • Proper pruning can help prevent or minimize problems by:

    • improving air circulation within the tree, thus reducing the potential for foliar diseases; 

    • improving tree strength and inducing branching;

    • removing dead or broken branches which may encourage disease/insect problems.

  • Refer to our guide to pruning trees

  • Fire blight disease can be managed with a technique called ugly stub pruning.

Troubleshooting a Declining Ornamental Fruit Tree

Examine the 6-8 inch area just above and below the soil line and look for the following:

1. Is gummy sap present? Gummosis is extruded sap from any damaged area of the bark and can be caused by a variety of environmental conditions (e.g., soil saturated with water). Peachtree borers are associated with heavy gummosis along the lower trunk and may extend below the soil level. The tree produces the gum as an attack response to the borer. 

2. Is there evidence of vole feeding? Voles (meadow mice) can girdle and kill a tree by feeding at the base of the trunk. Damage is more likely during a cold winter with deep snow cover. 

3. Do you notice cankers and browning of the tissue under the bark? Scrape away some of the tree bark (especially on the most symptomatic side of the tree). This indicates Phytophthora root rot or Verticillium wilt. These soil-borne fungal diseases are more prevalent on wet soils. The foliage of infected trees tends to yellow gradually and drop during the summer.

4. With the bark scraped away, can you see white, fan-shaped fungal mats between bark and wood? This is Armillaria root rot. Infected trees tend to collapse in mid-summer.

5. Is the bark spongy and thickened? With the bark scraped away, small pits or grooves in the wood indicate stem pitting (tomato ringspot) virus which is spread by weeds and nematodes.

Key to Common Problems of Ornamental Fruit Trees

Location of Symptom

Symptom Details

Possible Causes

Comments/Management

Leaves

Spots, yellowing, or browning

Environmental factors: temperature and weather extremes, frost, bud injury

These are often minor symptoms. Reduce plant stressors to the extent possible (e.g., water during drought, improve drainage, choose plants suitable to the location).

Leaf spots or blotches

Apple and pear scab: olive-brown velvety fungal spots on leaves.

Plant resistant varieties. Rake up and discard all leaves, fruit, and debris.

Rust diseases: bright yellow or orange spots or fungal growths (cedar-hawthorne, cedar-quince, and cedar-apple rust diseases).

Plant resistant varieties. Cedar trees are the alternate host of these diseases.

Cherry leaf spot: small purple fungal spots on leaf surfaces. Leaves develop holes and turn yellow. Infected leaves often drop.

Plant resistant varieties.

Plum leaf spot: fungal leaf spot similar to cherry leaf spot but spots are smaller.

Plant resistant varieties.

Pear leaf blister mite: on apple and pear. Small green or yellow pimples turn into reddish-brown blisters. Tiny white or light-red mites can be seen on leaf undersides with a hand lens.

Apply dormant oil spray before bud break in the spring.

Burning from pesticide or fertilizer: light-colored spots from direct contact. Random or regular pattern of browning.

Follow mixing directions carefully. Apply on windless days. Shield valuable plants.

White powder on leaves and buds

Powdery mildew: white surface growth on leaves that may cause distortion.

Plant resistant varieties. Rake up fallen leaves in the fall. Remove damaged shoots and prune for improved air circulation. If powdery mildew was a problem the previous year, spray with wettable sulfur at bloom. Another option is to check horticultural oil labels for powdery mildew control listings.

Leaf yellowing or browning

Spider mites: period-sized pest feeds mostly on leaf undersides, causing stippling pattern of tiny white/yellow dots) and bronzing. Damage is more severe during hot weather.

Spray with dormant oil during pre-bloom period. Avoid broad-spectrum insecticides that kill mite predators and often worsen the problem.

San Jose Scale: gray to brown scale covers (1/16”) with central yellowish white bump. Found on bark where leaf wilting and dieback are first noticed. Yellow crawlers are present in early June, late July, and early September. Covers of overwintering immatures are gray with white central rings.

Produces a toxin that turns inner bark red. Light infestations may cause leaf wilting and branch dieback. Heavy infestations may kill trees. Prune off infested branches showing dieback. For heavy infestations, use a summer oil spray when crawlers are active. Spray with a dormant oil to control light infestations.

Green Peach Aphid: leaves curl, yellow and drop. Aphids secrete honeydew which may lead to sooty mold on foliage.

Primarily an early-season problem. A strong water spray will dislodge aphids. Apply a dormant oil spray at bud swell.

Fire Blight: bacterial disease that causes entire shoots to quickly die. Leaves turn brown/black but do not fall off. Shoot tips may curl over giving a “shepherd’s crook” appearance.

Plant resistant varieties. During the growing season, prune out infected parts using the “ugly stub” pruning method. (See tip at end of this publication.) Otherwise, dormant pruning of cankers is recommended. Spray Bordeaux or fixed copper spray at bud break for severe infections. Reduce or eliminate nitrogen applications.

Cankers, Phytophthora, Verticillium wilt, Armillaria root rot: dark or loose bark usually sunken. Fungal growth is sometimes visible under loose bark.

Remove tree.

Excessive water: older leaves uniformly yellow.

Modify soil for better drainage.

Drought stress: first observed on newer growth.

Keep trees well watered during extreme drought.

Leaf scorching /marginal burning

Drought stress: marginal (leaf edge) browning.

Upper leaves affected first. Irrigate during dry weather.

Fertilizer burn/root damage: upper leaves affected first. Excessive fertilizer applications can cause root dieback.

Avoid over-application of fertilizers.

Pesticide burn: including soaps and oils. Stressed plants are more likely to be burned. Emulsifiable concentrates are more likely to burn than wettable powders.

Leaf margins are affected first. Leaves are particularly susceptible to burn when temperatures exceed 80-85°F. Copper, sulfur and other organic fungicides may cause leaf burn.

Damage from herbicides (including dicamba and glyphosate): stunted, off color growth caused by drift onto foliage or absorption by roots.

Symptoms from fall-applied herbicides may not appear until spring.

Leaves curled, twisted or rolled

Peach leaf curl: fungal disease on unfolding leaves in spring. Leaves are thickened, malformed and brightly colored (purple, red, orange). Severe when spring weather is cool and wet. May cause significant defoliation. Plum pockets is a similar disease affecting plum.

Apply a pre-bloom spray of liquid-lime sulfur on all tree parts. If leaf curl was severe the previous year, apply Bordeaux mixture before buds swell in the spring.

Green Apple Aphid, Rosy Apple Aphid: also feeds on buds. Black sooty mold growing on honeydew  may be observed.

Early season problem. Aphids spread fireblight. A strong water spray will dislodge aphids. Reduce or eliminate nitrogen applications.

Herbicide injury: new growth appears twisted and curled.

Tree should recover from moderate damage.

Leaves drop in late spring

Stressed trees with reduced winter food reserves are unable to sustain new growth.

Provide good tree care during the growing season. Water during drought.

Leaves with black/sticky coating

Sooty mold: fungal growth on honeydew (sticky excrement) from aphid or soft scale feeding.

If problem is severe, spray a summer rate of horticultural oil to control aphids. Apply a dormant spray of horticultural oil to control soft scale infestations.

Holes in leaves

Shothole: disease on many trees in the genus Prunus. Brown spots on leaves eventually fall out leaving circular holes.

Disease rarely affects the health of tree.

Leaves chewed

Various caterpillars: holes in leaves or portions of leaves missing.

Inspect trees throughout the growing season. If severe, handpick or spray young larvae with a Bt product.

Japanese Beetles: skeletonize leaves.

Handpick or use a registered insecticide if necessary.

Serpentine trails or blotches in leaves

Various leafminers (maggots or small caterpillars): feed between the upper and lower leaf surfaces.

Control is difficult on large trees. Usually no control is necessary. Pick off infested leaves if damage is significant.

Webbed or tented foliage

Tent caterpillars, webworms, leafrollers and leaf tiers: various caterpillars found within webbed leaves or silken tents.

If numerous caterpillars are present, use a Bt product when the caterpillars are small. Knock down or prune out webs on terminal branches and destroy caterpillars.

Wilted foliage

Drought stress: foliage wilts, droops and drops prematurely.

May lead to twig and limb dieback. Provide adequate water during summer and fall months.

Root damage: freeze, drought, mechanical injury or root diseases.

Prune out affected areas and keep trees well watered and protected.

Wet, poorly drained/heavy clay soils: limits root growth. May also lead to root diseases.

Select suitable, well-drained planting sites. Standing water drowns roots.

Dry sites/insufficient watering: especially important for newly transplanted trees.

Keep young and newly transplanted trees well watered.

Peachtree Borer: (primarily on peach, cherry and nectarine.) White larvae 1 1/4 inches long with brown head. Female adult clear wing moth is large, with a black band on the tip of each front wing. Larvae feed in tunnels below bark at base of tree and overwinter, renewing activity in early spring.

Larvae can be speared with thin wire inserted into holes. If no sap is oozing from holes and frass is observed, beneficial nematodes (Steinernema carpocapsae) may be used for control. 

Reduce tree stress. Avoid injuries, damage, and soil compaction. 

Oriental Fruit Moth: 3/8-inch long larvae with brown-black head bores several inches into new shoots. Larvae overwinter in tree crevices and groundcover. Young, rapidly growing trees are more severely affected.

Prune out and dispose of wilted tips 6 inches below visible damage. Remove fallen fruit debris from the ground at the end of the season.

San Jose Scale: gray to brown scale covers (1/16”) with central yellowish white bump. Found on bark where leaf wilting and dieback are first noticed. Yellow crawlers are present in early June, late July, and early September. Covers of overwintering immatures are gray with white central rings.

Produces a toxin that turns inner bark red. Light infestations may cause leaf wilting and branch dieback. Heavy infestations may kill trees. Prune off infested branches showing dieback. Spray with a dormant oil to control light infestations. For heavy infestations, use a summer oil spray when crawlers are active.

Shoots, Branches, Trunk

Shoots wilt and bend at ends (shepherd’s crook); sunken, black or wine colored cankers

Fire Blight: bacterial disease that causes entire apple and pear shoots to quickly die. Leaves turn brown/ black but do not fall off. Shoot tips may curl over giving a “shepherd’s crook” appearance.

Plant resistant varieties. During the growing season prune out infected parts using the “ugly stub” pruning method. (See tip at end of this section.) Otherwise, dormant pruning of cankers is recommended. Spray Bordeaux or fixed copper spray at green tip stage of bud development for severe infections. Reduce or eliminate nitrogen applications.

Dark, sunken cankers; gummosis may be observed

Various fungal and bacterial diseases (especially Cytospora canker): Enters through insect feeding or lawnmower wounds, frost cracks, or hail damage.

Prune out and dispose of infected wood below visible damage. Prune on dry, warm days in early spring. Do not leave stubs. When necessary, fertilize only in late winter or early spring. Apply outdoor white latex paint to trunk and large branches after leaf fall to prevent frost cracks.

White, woolly, waxy material on new growth

Woolly Apple Aphid: dark aphids under fluffy white wax on exposed roots, wounds on trunks and branches, and at the bases of new shoots. Heavy infestations on the roots of small trees may kill them. Heavy infestations on large trees may deform twigs and branches and cause the trees to be unthrifty.

Usually controlled by parasitic wasp (Aphelinus mali). Horticultural oil or soap sprays in spring reduce large infestations until wasps appear. Parasitized aphids turn into black mummies and the white wax disintegrates.

Silken webs/tents in branch crotches

Eastern Tent Caterpillar: caterpillars found within silken tents

Manually destroy the web contents in the evening during April. Prune out egg masses during the dormant season. (Egg masses look like black styrofoam on twigs.)

Black, gnarled swellings along twigs and branches

Black knot: (Prunus species) fungal disease of plum and cherry

Prune out and dispose of infected wood below visible damage.

Gum oozes from holes at base of trunk or lower branch crotches; sawdust-like frass may be observed.

Peachtree Borer: (primarily on peach, cherry and nectarine.) White larvae 1 1/4 inches long with brown head. Female adult clear wing moth is large, blue and orange, with a black band on the tip of each front wing. Larvae feed in tunnels below bark at base of tree and overwinter, renewing activity in early spring.

Larvae can be speared with thin wire inserted into holes. If no sap is oozing from holes and frass is observed, beneficial nematodes (Steinernema carpocapsae) may be used for control. 

Reduce tree stress. Avoid injuries, damage, and soil compaction.

Stress: weakens tree and makes it more susceptible to insect and disease problems.

Gummosis is extruded sap from any damaged area of the bark especially from insect borers.

Numerous small round holes in twigs and branches (gum may be evident)

Shothole Borers: numerous tiny holes along branch or trunk caused by small beetles.

Remove and destroy infested wood promptly.

Shoot/twig/branch wilting/ dieback

Fire Blight: bacterial disease that causes entire shoots to quickly die. Leaves turn brown/black but do not fall off. Shoot tips may curl over giving a “shepherd’s crook” appearance.

Plant resistant varieties. During the growing season prune out infected parts using the “ugly stub” pruning method. (See tip at end of this section.) Otherwise, dormant pruning of cankers is recommended. Spray Bordeaux or fixed copper spray at the green tip stage of bud development for severe infections. Reduce or eliminate nitrogen applications.

Root damage, drought or mechanical injury: affects water and nutrient uptake.

Prune out affected areas and keep trees well-watered and protected.

Wet, poorly drained soil: limited root growth.

Select suitable, well-drained planting sites.

Herbicide damage: stunted off color growth.

Avoid spray drift.

Oriental Fruit Moth: 3/8 inch long, larvae with brown-black head. Bore several inches into new shoots. Larvae overwinter in bark crevices and ground cover. Young, rapidly growing trees are more severely affected.

Prune out and dispose of wilted tips 6 inches below visible damage. Remove fallen fruit debris from the ground at the end of the season.

San Jose Scale: gray to brown scale covers (1/16”) with central yellowish white bump. Found on bark where leaf wilting and dieback are first noticed. Yellow crawlers are present in early June, late July, and early September. Covers of overwintering immatures are gray with white central rings.

Produces a toxin that turns inner bark red. Light infestations may cause leaf wilting and branch dieback. Heavy infestations may kill trees. Prune off infested branches showing dieback. Spray with a dormant oil to control light infestations. For heavy infestations, use a summer oil spray when crawlers are active.

Twigs/limbs broken or injured

Ice, wind or hail damage: disease cankers may develop. Small twigs may be pruned by squirrels for nest-building.

Prune out affected parts.

Bark cracked longitudinally, usually on south or west side

Frost/freeze cracks, sunscald: due to differential freezing and thawing of water in tree.

Consider wrapping trunks of young trees, especially on exposed sites. Apply outdoor white latex paint to trunk and large branches after leaf fall to prevent frost cracks.

Trunk gouged or scarred

Lawn mower or string trimmer injury: bark removed near base of tree.

Can lead to disease and borer problems. Mulch a wide circle around the tree but keep the mulch 6 inches from the trunk and less than 3 inches deep.

Embedded wires or collars: from tree support apparatus left on too long.

Remove wires or collars embedded in the trunk. If they cannot be pulled out, cut the wire or collar in several places to relieve the pressure.

Small reddish-brown and black bumps on 1-3 year old wood

Lecanium Scale: reddish-brown to black, 3/8 inch long bumps usually found on young wood.

Scrape off small colonies by hand. Spray with dormant oil and prune out damaged wood.

Roughened bark, clusters of hard, graycolored specks

San Jose Scale: gray to brown scale covers (1/16”) with central yellowish white bump. Found on bark where leaf wilting and dieback are first noticed. Yellow crawlers are present in early June, late July, and early September. Covers of overwintering immatures are gray with white central rings.

Produces a toxin that turns the inner bark red. Light infestations may cause leaf wilting and branch dieback. Heavy infestations may kill trees. Prune off infested branches showing dieback. Spray with a dormant oil to control light infestations. For heavy infestations, use a summer oil spray when crawlers are active.

White encrustations on large branches and trunk

White Peach Scale and White Prunicola Scale: crawlers feed on foliage. High populations can cause branch dieback, especially on Japanese flowering cherry.

Apply a dormant rate horticultural oil spray before bud break. For light infestations, scrape away scales with a soft brush.

Water sprouts, small vertical shoots along a branch or trunk

Response to environmental stress or removal of large branches and limbs: excessive green shoot growth.

Promptly pull or cut all water sprouts at point of attachment.

Suckers, proliferation of young shoots.

Numerous green shoots: at base of tree, grow from root stock.

Promptly pull or cut at point of attachment.

Shoots chewed, trunk girdled, bark stripped from trunks and branches

Deer feeding and antler rubbing by bucks: worse during very cold snowy winters.

Where appropriate, electric fences are very effective. Repel deer by hanging one or more of the following from mesh bags on trees: small soap bars, human hair, or dried blood meal. Commercial repellents are also available. Wrap the trunks of newly planted trees with commercial tubes or wraps, or make cylinders from hardware cloth or chicken wire 

Roots and base of young trees chewed

Voles (meadow mice), rabbits: nest in mulch, weeds and plant debris around trunk. More serious problem during very cold winters.

Keep grass mowed and mulch pulled back from the trunk. Place tree guards (18 inch high cylinders formed from hardware cloth) around trees which should extend 2-3 inches below the soil line. Use mouse traps to reduce vole populations.

Bulging or deformity of trunk at graft union

Scion wood overgrows or undergrows the rootstock: causes an enlarged swelling.

Normal on grafted trees. Remove all suckers that arise below the graft union. If graft union is damaged or killed, sucker growth may outgrow desired scion stock.

Flowers/Fruits

Blasted or damaged blooms

Winter kill of buds: sustained cold temperatures.

Avoid planting in low areas or frost pockets.

Spring frost damage to buds and flowers: trees may leaf out without flowering. Leaf buds are hardier than flower buds.

Avoid planting in low areas or frost pockets. 

Misuse of dormant oil sprays or pesticide sprays: may kill leaf and flower buds.

Over-spraying pesticides, especially dormant oil, and liquid lime-sulfur, may damage buds and blooms. Sprays should be applied when temperatures are expected to be above above 40°F for 24 hours. Do not apply oil sprays 30 days before or after pesticide applications such as captan, carbaryl, dimethoate, or products containing sulfur. Check product label carefully

Blossom drop

Spraying pesticides on open blooms: may damage tender tissue.

Spraying pesticides may damage buds and blooms. Follow label directions.

Water stress: may cause desiccation of buds.

Irrigate during dry periods.

Stressful conditions: drought, wind, low temperatures.

Avoid planting in problem sites.

Over-use of nitrogen fertilizers prior to bloom period: promotes excessive vegetative growth.

Reduce applications of high nitrogen fertilizers.

Failure to flower

Winter kill of buds: sustained cold temperatures.

Avoid planting in low areas or frost pockets.

Spring frost damage to buds and flowers: trees may leaf out without flowering. Leaf buds are hardier than flower buds.

Avoid planting in low areas or frost pockets.

Low light conditions.

Follow proper thinning and pruning guidelines. Situate plantings for optimum light exposure.

Over-use of nitrogen fertilizers prior to bloom period: promotes excessive vegetative growth.

Avoid excessive nitrogen application.

Severe pruning: will reduce number of blooms.

Do not prune spring flowering trees after July.

Spots on fruits

Scab: olive-brown velvety fungal spots on fruit. Lesions become corky

Plant resistant varieties. Rake up and discard all leaves, fruit and debris.

Fire Blight: bacterial disease that causes brown spots. Fruit eventually shrivels.

Plant resistant varieties. During the growing season prune out infected parts using the “ugly stub” pruning method (see tip at end of this section). Otherwise, dormant pruning of cankers is recommended. Spray Bordeaux or fixed copper spray at the green tip stage of bud development for severe infections. Reduce or eliminate nitrogen applications.

Orange growths on fruit

Rust: on Hawthorne, crabapple and Bradford pear fruit.

Plant resistant varieties. Do not plant cedar trees, the alternate host of the disease.

Authors: Mary Kay Malinoski, Jon Traunfeld, David Clement, University of Maryland Extension Specialists, Home and Garden Information Center, 2006. Revised 3/2020.

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