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