Plant Disease Management Handbook

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Apple (Malus spp.) - Crown Gall

Crown Gall Disease of Nursery Crops

Image related to Pear (Pyrus spp.)-Crown Gall

OSU Plant Clinic Collection, 2011.

Old Home x Farmingdale root stock with crown gall.

Larry Moore collection, 1991.

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Apple (Malus spp.) - Bitter Pit

Image related to Pear (Pyrus spp.)-Cork Spot

Note the subsurface discolored spots.

Neil Bell, 2008.

Anjou pears with cork spot.

OSU Plant Clinic Image, 2017.

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Quince (Cydonia oblonga) - Leaf Spot

Pear, Asian Cultivar Susceptibility

Image related to Pear, Asian (Pyrus spp.)-Fabraea Leaf Spot

Leaf spots on upper side of Asian Pear leaf.

Steve Castagnoli, 2011.

Leaf spots on lower side of Asian Pear leaf.

Steve Castagnoli, 2011.

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Pear (Pyrus spp.) - Pseudomonas Blossom Blast and Dieback

Pear, Asian Cultivar Susceptibility

Image related to Pear, Asian (Pyrus spp.)-Dieback

Joseph Postman, 2008.

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Cherry (Prunus spp.) - X-Disease

Pear (Pyrus spp.) - Decline

This slide is labeled Hale peach from The Dalles with western X disease."

OSU Extension Plant Pathology Slide Collection, 1950.

Tattered leaves due to X-disease.

OSU Plant Clinic Image, 2018.

Peach with tattered leaves due to X-Disease.

OSU Plant Clinic Image, 2018.

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Tree Wound Paints

Image related to Peach (Prunus persica)-Wood Decay

The interior of this tree trunk is almost completely rotted away.

Jay W. Pscheidt, 2007.

If you see any kind of fungal fruiting bodies such as these, there is wood decay in that branch.

Jay W, Pscheidt, 2008.

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Cherry (Prunus spp.) - Verticillium Wilt

Image related to Peach (Prunus persica)-Verticillium Wilt

The tree in the upper center has many dead branches due to Verticillium wilt.

OSU Extension Plant Pathology Slide Set, circa 1940's.

Discolored vascular system indicating Verticillium wilt.

David Sugar, 2008.

Discolored vascular system of these peach stems in cross section.

David Sugar, 2008.

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Apple (Malus spp.) - Fruit Rot, Phytophthora

Cause A physiological problem. The exact causes of pit breakage are unknown. Low temperatures and/or freeze damage during flowering and early fruit development may be factors. Fruit of most early peach cultivars enters the final swell of growth before the pit is completely hardened. As the fruit enlarges rapidly, stress exerted by the expanding flesh causes (or enhances) much of the pit fracturing.

Whole peach on the left has a split pit which can be see from the stem end as a hole. When cut open, fruit with split pits (as seen on the bottom) may be rotted, have insects or moldy growth inside when compared to healthy fruit (top).

Jay W. Pscheidt, 2007.

Cause Wilsonomyces carpophilus, a fungus that overwinters on infected peach (stone fruit) buds and twigs. When moisture is continuous for at least 24 hours and temperatures are above 36°F, infection can occur in the dormant season. When temperatures are higher during the growing season, shorter periods of moisture are required for germination and infection; for example, only 6 hours are needed at 77°F. Spores spread primarily by splashing water and can remain viable several months when dry.