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Late season fungicides needed to protect against fruit rot in storage. Photo: K. Peter, Penn State
Apple Disease, Pre- and Post-harvest - Keep Apples Free From Fruit Rot - Articles Articles
Management considerations are discussed for mitigating pome fruit rots before and after harvesting. More
Figure 1. Lodged corn seen from a distance.
Corn rootworms Suspected of Resistance to Bt Corn Varieties Discovered - Articles Articles
Western corn rootworms that developed resistance to some Bt corn varieties may now be a problem in PA. More
A declining tree with bark removed from graft union to show necrosis. Note numerous rootstock suckers. (Photo: K. Peter)
Apple Disease - Rapid Apple Decline (RAD) or Sudden Apple Decline (SAD)? - Articles Articles
There is a mystery surrounding rapid apple decline/sudden apple decline of young, dwarf apple trees. More
Plum Pox Virus
Plum Pox Virus - Articles Articles

Plum Pox Virus

Kari A. Peter, Ph.D.

Plum pox virus (PPV), or Sharka, is a viral disease that infects not only plum but other economically important Prunus species. More
Young galls are light in color and with age become dark and hard, ½ inch to 3 or 4 inches in diameter. Photo by B. Butler.
Tree Fruit Disease - Crown Gall - Articles Articles

Tree Fruit Disease - Crown Gall

Kari A. Peter, Ph.D.

Crown gall is caused by a bacterium, Agrobacterium tumefaciens, and affects apples, pears, quince, peaches, nectarines, apricots, plums, and cherries. 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
Pear Disease - Stony Pit
Pear Disease - Stony Pit - Articles Articles

Pear Disease - Stony Pit

Kari A. Peter, Ph.D.

Stony pit of pear is presumed to be caused by a destructive virus, but the virus has not been isolated. Affected fruit are unsightly and unmarketable. More
Photo by K. Peter.
Pear Disease - Sooty Mold - Articles Articles

Pear Disease - Sooty Mold

Kari A. Peter, Ph.D.

Sooty mold fungi of the genus Capnodium cause an unsightly blackening over the surface of fruit and leaves. 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
Source: Joseph OBrien, USDA Forest Service, Bugwood.org
Plum Disease - Plum Leaf Spot - Articles Articles

Plum Disease - Plum Leaf Spot

Kari A. Peter, Ph.D.

Leaf spot of plums and prune-type plums is caused by the fungus Coccomyces prunophorae. More
Source: William M. Brown Jr., Bugwood.org
Peach Disease - Powdery Mildew of Peach, Nectarine, and Apricot - Articles Articles
Powdery mildew, Sphaerotheca pannosa, sometimes called rose mildew (it affects some woody ornamentals), is not often serious. More
Source: Bruce Watt, University of Maine, Bugwood.org
Stone Fruit Disease - Powdery Mildew of Cherry and Plum - Articles Articles
The disease is caused by Podosphaeria oxyacanthae, one of the common species of the powdery mildew group of fungi. More
Source: Mike Schomaker, Colorado State Forest Service, Bugwood.org
Stone Fruit Disease - Plum Pockets - Articles Articles

Stone Fruit Disease - Plum Pockets

Kari A. Peter, Ph.D.

In the northeastern United States, the most important disease affecting American-type plums is known as plum pockets, or bladder plum. It is caused by Taphrina communis. More
Source: Mary Ann Hansen, Virginia Polytechnic Institute and State University, Bugwood.org
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: John Hartman, University of Kentucky, Bugwood.org
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
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