Plant Disease Management Handbook

Cause Pectobacterium carotovorum and Dickeya chrysanthemi, bacteria that can spread by workers' hands, cutting tools, or contaminated water supplies. It also can survive in plant debris. Wounds are a common entry way for the bacteria. Any factor that stresses cuttings favors the disease such as long shipping times. Cool temperatures may delay symptoms until warm weather occurs.

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Geranium (Pelargonium spp.) - Bacterial Blight

Cause Curtobacterium flaccumfaciens pv. poinsettiae, a bacterium that can be spread by cutting tools, and hands, working from infected to healthy plants, splashing water, and in contaminated growing media, Infection of leaves occurs through stomates. Warm growing conditions and high-nitrogen fertility have been associated with the disease. Has become a rare problem but can still be found to cause problems.

Image related to Poinsettia (Euphorbia pulcherrima)-Bacterial Canker

Spots and blotches may be on leaves, which fall prematurely.

OSU Plant Clinic Image, 2014.
Image related to Poinsettia (Euphorbia pulcherrima)-Bacterial Canker

Elongate cankers on the stems may be discolored and crack.

OSU Plant Clinic Image, 2014.
Image related to Poinsettia (Euphorbia pulcherrima)-Bacterial Canker

Spots and blotches may be on leaves, which fall prematurely.

OSU Plant Clinic Image, 2014.

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Cherry, Flowering (Prunus spp.) - Brown Rot Blossom Blight

Image related to Plum, Flowering-Brown Rot Blossom Blight

Can see sporulation of the fungus on these blighted tissues.

Robin Rosetta, 2009.
Image related to Plum, Flowering-Brown Rot Blossom Blight

Brown rot blossom blight on purple leaf plum.

Robin Rosetta, 2009.

Shoot dieback and dead flowers due to brown rot.

Jay W. Pscheidt, 2007.

Image related to Plum, Flowering-Brown Rot Blossom Blight

Shoot dieback on purple leaf plum from brown rot infection in the spring.

Robin Rosetta, 2009.

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Prune and Plum (Prunus spp.)

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Gooseberry and Currant (Ribes spp.) - Blister Rust

White pine exhibiting symptoms of blister rust infection, including swelling, flagging, and remnants of resinosis. 

Zolton Bair, 2014.

Western white pine needle spots.

Jeff Stone.

Early symptoms of rust showing pycnial ooze on white bark pine. Also note needle spots in lower right part of image.

Jeff Stone.

Resinosis associated with blister rust infection on white pine. 

Zolton Bair, 2014.

Aecial pustules emanating from bark around blister rust canker on white pine

Zolton Bair, 2014.

Image related to Pine, White-White Pine Blister Rust
This shows the active aecia of this rust fungus.
Photo by Everett Hansen, 1981.

Orange aecial pustules emerging from white pine blister rust stem canker.

Zolton Bair, 2014.

One pine seedling

Suspected White Pine Blister Rust damage on needles of white pine seedling.

Zolton Bair, 2014.

Cause Endocronartium harknessii (formerly Peridermium harknessii), a fungus. The disease is commonly found on the hard pines, particularly those with two needles in the fascicle. Shore pine (Pinus contorta), lodgepole pine (P. contorta var. latifolia), mugo pine (P. mugo), Scots pine (P.

Numerous galls can occur in susceptible trees.

Jay W, Pscheidt, 2008.

Note the swollen lodegepole pine trunk.

Photo by Kathy Merrifield, 1989.

Image related to Pine (Pinus spp.)-Western Gall Rust
Orange pustules are the active aecia (spore producing body) of this fungus.
Photo by Everett Hansen, 1980.
Image related to Pine (Pinus spp.)-Western Gall Rust
This is a typical gall produced by this disease.
Photo by Everett Hansen, 1999.

Cause Diplodia sapinea (formerly Sphaeropsis sapinea), a fungus. Has become more of a problem in Idaho and Oregon on ponderosa pine. Also is a problem on Austrian, Scots, red, and mugo pine. The disease normally does not kill trees but allows other organisms (such as pine beetles) to gain entry, which may kill the tree. Generally a problem on older trees. Trees that are stressed because of poor site, drought, snow damage, or insect activity are very susceptible.

The shoot tip dies back to the main stem. Diplodia on red pine.

Melodie Putnam, 1990.

Image related to Pine (Pinus spp.)-Tip Blight
Tip blight on Austrian pine.
Photo by Melodie Putnam, 1990.
Image related to Pine (Pinus spp.)-Tip Blight
Note how the shoot dies from the tip backwards.
Photo by Melodie Putnam, 1987.

Austrian pine cone scales with Diplodia (Sphaeropsis) sp.

Photo by Melodie Putnam, 1993.

Image related to Pine (Pinus spp.)-Tip Blight
Ponderosa pine on a marginal site with Spaeropsis tip blight.
Max Bennett, 2010.

See:

Spruce (Picea spp.) - Tip Blight

Cedar (Cedrus spp.) - Needle Blight

Image related to Pine (Pinus spp.)-Sirococcus Shoot Blight

Needle tip dieback due to Sirococcus on this Ponderosa pine.

OSU Plant Clinic collection, 2012.
Image related to Pine (Pinus spp.)-Sirococcus Shoot Blight

Small, dark pycnidia can be seen on the stem of this Ponderosa pine.

OSU Plant Clinic collection, 2012.

Dieback on these whitebark pine (Pinus albicaulis) shoots due to Sirococcus sp.

OSU Plant Clinic, 2022.

Cause Salt damage to shore pine is a common phenomenon along the coast in certain years. Violent storms and high winds along the coast pick up salt spray (usually in winter) and can blow this inland a considerable distance. Salt interferes with normal biological function of the needle and will kill part or all of a shore pine needle.

These pines have brown needles due to salt injury. Snow was plowed from parking lot but piled beneath trees. Snow melted away leaving behind salt (MgCl) used to melt ice from the road in the winter.

Jay W. Pscheidt, 2019.