Problems of Apple Trees

 Problems of Apple Trees

Many backyard fruit growers have no major problems affecting the quality of their fruit harves.  In almost all these cases, the fruit tree is growing in soil that contains at least 5% organic material, is mulched with organic mulch 365 days a year, and is watered or fertilized only when needed. 

Commercial orchards suffer from attacks by dozens of different insects and disease.  Do not get discouraged because the home grower is seldom bothered by more than a couple of problems in any growing season. We cover here only the six most common in detail. 

While it is always a good practice to spray your apple trees in late February with a dormant oil spray, we see no reason to institute a general all fits all spray program for your apple trees.  Fix the soil, keep the mulch in place, and help your trees reduce stress. 

Reducing Stress In Apple Trees

As you will see in the caring for apple trees section, we recommend spraying your trees with a seaweed extract mixed with a product called Thrive which contains beneficial microbes on a monthly basis throughout the year.  These monthly sprays will help reduce any stress caused by weather or anything else.  A tree with less stress seldom is hit with a pest insect or disease.





Most Common Pest Insects Attacking Apples

There are a variety of insect pests that attack and damage apples. Apple maggots, codling moths and plum curculio are some of the most common pests that will reduce or destroy an apple crop.

Most Common Diseases Attacking Apples

There are many diseases that can attack apple trees, however the most common and destructive apple tree diseases include Powdery Mildew, Apple Scab and Fireblight. Fireblight can destroy an apple tree, while mildew and scab can dramatically reduce the apple crop and even cause the tree to (drop)all its leaves.






Apples have worms - Apple Maggots

Small Brown Spots on Fruit - Black Rot

Tunnels inside of apples - Codling Moth

Tiny Pale-yellow Spots on Leaves  - Cedar Apple Rust

Gray, Velvety Mold On Leaves - Powdery Mildew

Withered and Dead Blossoms - Fire Blight

Foliage curls, puckers, turns yellow - Aphids

Leaves Stippled Yellow, discolored and distorted, white dots appear [[L838::Mites]]

Twig Dieback; Foliage Loss - Scale

Leaf Buds and Early Bark Eaten - Weevils

Defoliated Tree; Egg masses appear on trunk and branches - Gypsy Moth Caterpillar

Apples Fall, Have Cuts in Skin - Plum circulio beetle

Olive Green Spots on Undersides of Leaves; leaves cracked and distorted; apples develop spots - Scab






Small Brown Spots on Fruit 

Black Rot  A fungus, black rot does not become evident until a few weeks before fruit maturity or after harvest when it appears as storage rot. Black rot symptoms show on the apples.  Small brown spots develop on the apples, frequently at a wound.  They later expand and darken, finally turning black.  Concentric zones of alternating shades of brown and black appear around these lesions.  Minute black pimples may later develop as the apples shrivel and mummify.  During the growing season, the fungus attacks bark, twigs, and fruit, and over-winters in these tissues.  Use an approved fungicide as directed.  Prune out infected wood and destroy mummified fruit.


Tiny Pale-yellow Spots on Leaves 

Cedar Apple Rust - Cedar apple rust causes pale yellow, pinhead-sized spots on the upper surfaces of apple leaves.  These spots enlarge and turn bright orange on foliage and fruit.  This rust originates on nearby cedar trees, forming swellings, or galls, on their bark.  Junipers and hawthorns can also spread cedar apple rust to apple trees.  Spray apple trees with fungicide when cedar galls are releasing spores in the early spring.  Remove all red cedar trees within 300 yards of the apple tree. Apple varieties resistant to Cedar Apple Rust include Liberty, Nova Easygro, Novamac, Priscilla, and Redfree.  


Gray, Velvety Mold On Leaves 

Powdery Mildew  Powdery mildew is a fungus that covers the tips of twigs, leaves, and blossoms with white to pearly gray velvety mold.  Twigs are dwarfed, and the terminal bud is killed, which causes staghorn growth of side shoots.  Young apples develop russeting or etching.  To control powdery mildew, apply an approved fungicide, such as 95 percent flowable sulfur, before bloom and every other week until June 15 (as described in the spray program).  Prune infected terminals for additional control.  Mildew gets worse with periods of high humidity.  You can prevent mildew problems by growing resistant apple varieties, spacing and pruning to improve aeration and reducing shade over the tree.  Water early in the day, taking care to avoid wetting the foliage.  Reduce nitrogen enriched feedings to avoid excessive late season growth.  Resistant varieties include Akane, Delicious, Discovery, Golden Delicious, Liberty, Lodi, Macfree, Prima, Priscilla, Red Delicious, Redfree, Sir Prize, Spartan, and Tydeman’s Red.


Withered and Dead Blossoms 

Fire Blight  Fire-blight fungus can be one of the most serious pests of apple trees.  Very few trees are completely resistant and those that are usually produce poorer fruit.  While it is a major problem, it is a disease that can be controlled with correct fertilization and pruning.


Shoots infected with fire blight turn brown or black as though scorched. The blossoms wither and die. Water-soaked reddish bark lesions appear, and on warm days they ooze an orange-brown liquid.  Later they become brown and dry.  The best defense against fire blight is diligent pruning. In the winter, look for affected branches with visible cankers, and prune them off just a few inches below the cankers. On limbs too large to remove, pare away diseased tissues, sealing the wounds with tree paint.  In the summer, watch for blackened leaves, stems, or fruits, and cut them off 12 inches below any sign of disease. Also snap off vigorous suckers thrown up along branches and from the rootstock. These parts are very prone to fire blight.  It is VERY IMPORTANT not to forget to disinfect your pruning tool in a bleach solution (one part household bleach to four parts water) after each cut!  Hold the shears in the solution for at least 2 seconds to disinfect.  Resistant varieties include Akane, Baldwin, Delicious, Liberty, MacFree, McIntosh, Northern Spy, Nova Easygro, Novamac, Prima, Redfree, Red Delicious, Winesap, and Stayman.  



Leaves wrinkled or curled; discolored, stunted, tend to fall off          Aphids

Black sooty mold on honeydew made by ants herding aphids.          Ants Herding Aphids

Many holes in trunk and branches; small limbs girdled sawdust at holes          Borers

Skeletonized leaves           Cankerworms

Ends of twigs die and fall off.          Cicadas

Small hole in fruit; sawdust-looking material around hole; interior of fruit dark, rotted.          Caterpillar Of Codling Moth

Holes chewed in leaves, leaf stalk, stems; plant wilts, dies.          Cucumber Beetles

Fruit falls, crescent –shaped cuts in skin of fruit          Curculios

Leaves and twigs webbed together          Fall Webworms

Small misshapen fruits          Fruit Flies

Trees defoliated, brown egg cases appear on trunk          Caterpillar Of Caterpillar Of Gypsy Moths

Holes in leaves and flowers          Japanese Beetles

Foliage yellowed or white mottling, glaze of honeydew; plant weakens          Leafhoppers

Tip of leaves brown, internal larvae trails visible. Sometimes leaves skeletonized and rolled up.           Leaf Miners

Holes in flowers; leaves rolled up          Leafrollers

Cottony white masses on roots, stems, branches leaves; reduced plant vigor          Mealybugs

Leaves yellowed and may drop          Psyllids

Weaken plant, stunting growth, fewer blooms and fruit.           Sawflies

Leaves yellow, drop; bumps on leaves and stems; sometimes sticky material on leaves          Scale

Leaves stippled, yellow, dirty; webbing on interior stems of plant          Spider Mites

Deformed or dwarf flowers.          Tarnish Plant Bugs

Webbed nest in tree branches filled with caterpillars          Tent Caterpillars

Leaves discolored; black fecal spots on underside of leaf.          Thrips

Much foliage is eaten starting from top of tree down          Caterpillar Of Caterpillar Of Tussock Moth

Mottled, crinkled foliage; brown specks appear on tubers, and plants may droop and die prematurely          Mosaic Virus

White spots on leaves; eventually entire leaf is covered with powder          Powdery Mildew, A Fungal Disease

Orange or brown pustules on leaves          Rust, A Fungal Disease

Blossoms turn brown, die; young twigs wilt, tips down, brown, die          Fireblight

Roots rot and plant dies          Southern Blight, A Fungal Disease

Skin of fruit pierced or partially eaten          Birds

Foliage and fruit disappears below ten feet          Deer

Bark on lower trunk peeled away          Rabbits

Bites taken out of fruit          Squirrels

Bark chewed near soil surface          Mice