Plant Disease Management Handbook

Cause Colletotrichum acutatum (syn. Glomerella acutata), C. coccodes, C. gloeosporioides (syn. G. cingulata) and C. truncatum (syn. C. capsici) have been reported on pepper.

See:

Greenhouse Plants, Ornamental - Impatiens Necrotic Spot

Via assay this sample was positive for Tobacco rattle virus.

OSU Plant Clinic, 2023.

The leaves in the lower right of this image with yellow ring spots and line patterns tested negative for TSWV and there were no rod shaped particles when viewed with an electron microscope which would have been indicative of TRV.

Jay W. Pscheidt, 2020.

Note the yellow line patterns on these Tomato Spotted Wilt Virus infected leaves.

Photo obtained from Tom Allen, 1941.

Image related to Peony (Paeonia spp.)-Viruses

These line patterns and chlorotic ring spots on the leaves are caused by an undetermined virus.

Photo by Jay W. Pscheidt, 1999.

See:

Dahlia - Wilt

Cause The fungus Sclerotinia sclerotiorum causes stem rot in many plants and occasionally attacks peony. Overwintering sclerotia can survive many years in soil. The disease develops in cool, wet conditions and is more prevalent when plants form a complete, compact canopy that holds high relative humidity. The fungus can colonize dead organic plant matter and survive many years. Plants can be infected when host tissue colonized by the fungus comes in contact with healthy tissues.

The fungus can be seen growing in this stem lesion as a fluffy white mycelium.

OSU Plant Clinic image, 2024.

See:

Peony (Paeonia spp.) - Peony Red Spot

Dark purple glossy spots on upper leaf surfaces.

OSU Plant Clinic, 2022.

Image related to Peony (Paeonia spp.)-Leaf Blotch

Note the necrotic leaf margins on the curled leaves and some leaf spots.

Photo by Jay W. Pscheidt, 1999.

Spots can be numerous on susceptible plants.

Melodie Putnam, 2008.

Cause The fungi Botrytis paeoniae (sometimes called early blight or bud blast) and B. cinerea (sometimes called late blight). Additional species have been found in the PNW including B. pseudocinerea that is resistant to fenheximide. Inoculum of B. paeoniae will be from previous or nearby peony crops while that of B.

Image related to Peony (Paeonia spp.)-Botrytis Blight

Flowers can collapse prematurely from infection by this fungus.

Robin Rosetta

Shoots are collapsing due to infection by Botrytis.

OSU Plant Clinic collection, 2012.

Numerous leaf spots due to Botrytis.

Melodie Putnam, 2007.

These shoots are collapsing due to Botrytis.

Melodie Putnam, 2007.

This shoot has been cut in half lengthwise to show the discoloration of tissue near the ground.

OSU Plant Clinic Collection, 2011.

See:

Crabapple (Malus spp.) - Stem Rot

Image related to Pear, Flowering (Pyrus spp.)-Phytophthora Canker

Note the dark canker on the side of this trunk.

Photo by Rich Regan, OSU, NWREC.

Callery pear (Pyrus calleryana) branches with Phytophthora canker. Note the discolored bark in the upper image and then the discolored vascular cambium once the bark has been removed in the lower image.

Melodie Putnam image collection, 1997 (top) and 2000 (bottom).

See:

Pear (Pyrus spp.) - Decline

Pear (Pyrus spp.) - Stony Pit

Image related to Pear (Pyrus spp.)-Virus and Virus-like Diseases

Pear stony pit.

B.C. Ministry of Agriculture and Lands (Jesperson)

Cause Vein yellows reportedly is incited by a long, flexuous virus that is identical to or very closely related to apple stem pitting virus. The virus is found in many noncertified European pear cultivars, many of which show few if any symptoms. vein yellows virus and red mottle virus are strains of the same virus.

Image related to Pear (Pyrus spp.)-Vein Yellows (Red Mottle and Sooty Ringspot of Quince)

Notice the color of the infected leaf on the right.

OSU Extension Plant Pathology Slide Collection.

See:

Apple (Malus spp.) - Storage Problems

Cause There are many storage disorders caused by abiotic problems beyond Bartlett Decay described below. Many of these are covered in a separate section on Apple-Storage Problems.