Pests and Diseases

Recommendations for managing weeds, insects and diseases in fruit crops such as apples, pears, berries, cherries, peaches, grapes, pears and plums. Tips on using fungicides, antibiotics, insecticides and miticides.

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Bitter rot occurs only on fruit and can penetrate unbroken fruit skin. Photo by K. Peter.
Apple and Pear Disease - Bitter Rot - Articles Articles
Bitter rot on apple and pear fruit is caused by the pathogenic fungi Colletrotrichum gloeosporioides and C. acutatum. More
Injuries to fruit, especially during picking and handling operations, are the primary points of entry. Photo by K. Peter
Apple and Pear Disease - Blue Mold - Articles Articles
Blue mold, a common rot of stored apples and pears, is caused by the fungus Penicillium expansum. More
Apple and Pear Disease - Fire Blight, Dormant Removal of Cankers
Apple and Pear Disease - Fire Blight, Dormant Removal of Cankers - Articles Articles
When it comes to managing fire blight, the first line of defense is good sanitation, which is removing the overwintering source for the bacteria: cankers. More
Once established in the wound, the fungus can quickly spread from infected fruit to adjacent healthy fruit during storage. Photo by K. Peter.
Apple and Pear Disease - Gray Mold - Articles Articles
Gray mold, Botrytis cinerea, is the most important postharvest disease of pears and is second to blue mold in importance to apple. More
The fungus survives in the soil as spores. Populations of these spores in the soil increase one to two months after fruit have been harvested. Photo by K. Peter.
Apple and Pear Disease - Mucor Rot - Articles Articles
Mucor rot is a fungal disease of apples and pears. The disease is a postharvest storage problem. More
Source: Dalphy O.C. Harteveld; Apple and Pear Australia Ltd. Used under Creative Commons 2.0 license:
Apple Disease - Alternaria Leaf Blotch - Articles Articles
Alternaria leaf blotch, caused by Alternaria mali, is a disease that affects apple leaves. More
Typical fruit lesions are distinct, almost circular, rough-surfaced, olive-green spots up to ¾ inch in diameter. Heavily infected fruits are usually misshapen and may crack and drop prematurely. Photo by K. Peter.
Apple Disease - Apple Scab - Articles Articles

Apple Disease - Apple Scab

Kari A. Peter, Ph.D.

Apple scab, Ventura inaequalis, is Pennsylvania's most important apple disease, attacking wild and cultivated apple and crabapple. More
Source: H.J. Larsen,
Apple Disease - Apple Union Necrosis and Decline - Articles Articles
Apple union necrosis, caused by tomato ringspot virus, affects the graft union of apple trees, resulting in gradual tree decline. More
Fruit rot usually appears at the calyx end of the fruit. There is usually one spot per fruit, a characteristic that distinguishes black rot from bitter rot. Photo by K. Peter.
Apple Disease - Black Rot and Frogeye Leaf Spot - Articles Articles
The black rot and frogeye leaf spot fungus, Botryosphaeria obtusa, covers a wide geographical range, attacking the fruit, leaves, and bark of apple trees and other pomaceous plants. More
Source: John Hartman, University of Kentucky,
Apple Disease - Blister Spot on Crispin (Mutsu) - Articles Articles
Crispin apples are highly susceptible to blister spot bacterial infection, Pseudomonas syringae, about 2 weeks after petal fall for a period of 2 to 4 weeks. More
Source: Mary Ann Hansen, Virginia Polytechnic Institute and State University,
Apple Disease - Blossom End Rot - Articles Articles

Apple Disease - Blossom End Rot

Kari A. Peter, Ph.D.

Blossom end rot, Botritis cinerea, is not a major problem in Pennsylvania orchards. Because it occurs only infrequently, very little is known about its cycle and control. More
Source: K. Yoder.
Apple Disease - Brooks Fruit Spot - Articles Articles

Apple Disease - Brooks Fruit Spot

Kari A. Peter, Ph.D.

Caused by the fungus Mycosphaerella pomi, Brooks fruit spot is also known as Phoma fruit spot. The disease attacks apple and crabapple trees and is rarely found in well-sprayed orchards. More
A characteristic symptom of shoot blight is the bending of terminal growth into the shape of a shepherd’s crook. Photo by K. Peter.
Apple Disease - Fire Blight - Articles Articles

Apple Disease - Fire Blight

Kari A. Peter, Ph.D.

Fire blight, Erwinia amylovora, is a destructive disease that can attack some 75 species of plants of the rose family. More
The fungi enter the developing fruit through an opening in the calyx. Photo by K. Peter.
Apple Disease - Moldy Core - Articles Articles

Apple Disease - Moldy Core

Kari A. Peter, Ph.D.

Moldy core is caused by several different fungal pathogens. Many cultivars of apples are affected, including Delicious, which is very susceptible. More
The canker typically exhibits a few pink or coral fruiting structures of the fungus in mid-summer. Photo by S. Weikert.
Apple Disease - Nectria Twig Blight - Articles Articles
Nectria twig blight, caused by the fungus Nectria cinnabarina, is a minor disease that breaks out occasionally. More
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