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Common Diseases & Pests of Fruit Trees

As a fruit grower in the USA, you are sure to encounter some of these in your orchard, depending on your local growing conditions and your luck. The list is not comprehensive — you will probably encounter others that are not listed yet. Nor have we created a full guide to remedies, which would be too much to cover here, since management practices range from organic to conventional and everything in between. See our main Fruit Tree Diseases & Pests page, part of our Learn Trees section, for further resources.

Disease or Pest	Fruit Types Affected
Alternaria Leaf Blotch Alternaria leaf blotch is caused by the fungus Alternaria mali. It affects apples, and it is mainly encountered in southern states.<...	Apple
American Plum Borer and Dogwood Borer The American plum borer is the caterpillar of a grey-brown moth (Euzophera semifuneralis) with brown-red forewings. It infests plum, cherr...	Apple, Plum, Cherry, Apricot
Anthracnose Canker and Bull's-eye Rot Apple anthracnose is a fungal infection caused by Cryptosporiopsis curvispora (AKA Neofabraea malicorticis) and other closely rel...	Apple
Apple Blister Spot Apple blister spot is the name given to infections of Pseudomonas syringae pv. papulans on apple trees. Pseudomonas syringae<...	Apple
Apple Maggot The adult apple maggot, Rhagoletis pomonella, AKA "railroad fly," is a black-bodied fly that is slightly smaller than a hous...	Apple
Apple Scab Apple scab is caused by the fungus Venturia inaequalis. This fungus overwinters on fallen diseased leaves, and in spring, the fungi shoot ...	Apple
Bacterial Canker of Stone Fruit Bacterial canker (AKA gummosis and sour sap) is caused by two closely related strains of the bacterium Pseudomonas syringae, which is also...	Peach, Plum, Nectarine, Cherry, Apricot
Bacterial Spot Bacterial spot (AKA "bacteriosis" and "bacterial shot hole" and "XAP") is a disease caused by the bacterium Xanth...	Peach, Plum, Nectarine, Cherry, Apricot
Birds Most of us love birds and welcome them in our gardens; they are beautiful and we think of them as symbols of freedom and the spirit. But unless you...	Apple, Peach, Plum, Pear, Nectarine, Cherry, Apricot
Bitter Pit Bitter pit once went by the name "Baldwin spot" in America, and in Germany it is known as Stippen. This is not a disease, but a ...	Apple, Pear
Bitter Rot Bitter rot is a fungal infection of ripening fruit, primarily apples, pears, and grapes. It is caused by numerous species of Colletotrichum	Apple, Pear
Black Knot Black knot is a disease caused by the fungus Dibotyron morbosum, AKA Apiosporina morbosa. It affects primarily plums, but it is a...	Peach, Plum, Nectarine, Cherry, Apricot
Black Rot or Blossom End Rot or Frogeye Leaf Spot Black rot, AKA "Blossom End Rot" and "Frogeye Leaf Spot," is a disease primarily affecting apple and pear trees that are stress...	Apple, Pear
Brown Marmorated Stink Bug The brown marmorated stink bug (Halyomorpha halys), or BMSB, is a pest that is most problematic on the East Coast. It probably arrived in ...	Apple, Pear
Brown Rot, Blossom Blight, Fruit Rot Brown rot (Monilinia Fructicola and Monilinia laxa, AKA "blossom rot" and "blossom blight") is a devastating ...	Peach, Plum, Nectarine, Cherry, Apricot
Cedar-Apple Rust Cedar-apple rust (CAR) is the most common of the three rusts that infect apple trees (the other two being quince rust and hawthorne rust). CAR is a...	Apple
Cherry Leaf Spot Cherry leaf spot, AKA "shot hole disease" and "yellow leaf" is a destructive infection caused by the fungus Blumerilla jaap...	Cherry
Codling Moth This is the infamous worm in the apple. Codling moth (Cydia pomonella or Lepidoptera: Tortricidae) originated in Asia Minor, but ...	Apple, Peach, Plum, Pear, Nectarine, Cherry, Apricot
Crown Gall Crown gall is caused by a soil-born bacterium, Agrobacterium tumefaciens, and it affects all types of fruit tree. It enters the tree throu...	Apple, Peach, Plum, Pear, Nectarine, Cherry, Apricot
Deer Deer are cursed by almost every gardener in North America. They trample on flower beds, rub up against trees, and seem to eat practically everythin...	Apple, Peach, Plum, Pear, Nectarine, Cherry, Apricot
Fireblight Fireblight (or fire blight) is perhaps the most heartbreakingly destructive of the apple diseases. It is a widespread, highly infectious bacterial ...	Apple, Pear
Peach Leaf Curl Peach leaf curl is an infection caused by the fungus Taphrina deformans. It affects the blossoms, shoots, leaves, and fruit of peach and n...	Peach, Nectarine
Peach Tree Borer and Lesser Peach Borer Both peach tree borer and lesser peach tree borer are caterpillars of clearwing moths (Lepidotera: Sesiidae). These pests are extremely de...	Peach, Plum, Nectarine, Cherry, Apricot
Pear Psylla Pear psylla is a small insect that arrived in America from Europe in the 1830's. The adult female lays her eggs on a pear tree starting in late...	Pear
Pear Scab Pear scab is caused by the fungus Venturia purina. It is similar to apple scab but less common and less persistent. The fungus that causes...	Pear
Perennial Canker Perennial canker seems to have the most names of any fruit-tree disease. AKA "peach canker," "Cytospora canker," "Leucosto...	Peach, Plum, Nectarine, Cherry, Apricot
Phytophthora (Collar Rot, Crown Rot, Root Rot) Phytophthora, once considered fungi, are now classified as oomocytes or "water molds." These pathogens live in the soil, and if soil mois...	Apple, Peach, Plum, Pear, Nectarine, Cherry, Apricot
Plum Curculio The plum curculio (Conotrachelus nenuphar) is a "true weevil" or a "snout beetle" (look up a picture and you will see ...	Apple, Peach, Plum, Pear, Nectarine, Cherry, Apricot
Powdery Mildew Powdery mildew is a disease that afflicts a wide range of trees, vegetables, and flowers, and is caused by several different fungi, Podosphaera...	Apple, Peach, Plum, Pear, Nectarine, Cherry, Apricot
Pseudomonas Pseudomonas bacteria are found in moist conditions practically everywhere. You probably have a few between your toes right now. The specific bacter...	Pear
Quince Rust Caused by the fungus Gymnosporangium clavipes, quince rust affects apples and, to a lesser degree, pears. Like cedar-apple rust it require...	Apple, Pear
Replant Disease Replant disease is a sickness caused by a complex of soil-born pathogens that consists of fungi, oomycetes or "water molds," and nematode...	Apple, Peach, Plum, Pear, Nectarine, Cherry, Apricot
Rodents (Mice & Voles) Meadow voles (mice) and Pine voles are the #1 cause of fruit tree mortality. They are the heart disease of fruit trees. Meadow voles are 4.5-...	Apple, Peach, Plum, Pear, Nectarine, Cherry, Apricot
San Jose Scale San Jose scale is a destructive insect (Quadraspidiotus perniciosus) that probably arrived in America from China in the late 1800's. I...	Apple, Peach, Plum, Pear, Nectarine, Cherry, Apricot
Woolly Apple Aphid This aphid, Erisoma lanigerum, is a native to North America. The WAA or "woolly" may occur on the above-ground portions or on th...	Apple

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