Plant Disease Management Handbook

See:

Greenhouse Plants, Ornamental - Gray Mold

Canker in the middle of the stem caused by Botrytis.

Oregon State University Plant Clinic image, 2020.

Image related to Poinsettia (Euphorbia pulcherrima)-Gray Mold

This stem canker is caused by Botrytis cinerea.

Photo by Melodie Putnam, 1997.

Lesions are often noticed first on the edges of young leaves and bracts.

Photo by Melodie Putnam, 1992.

See:

Dracaena - Tip Burn

Note: Domestic water that contains chlorine and/or fluoride is usually not harmful to poinsettias. Toxicity of fluoride at >0.4 ppm in the water results in necrotic spots on the tips and margins of young leaves and bracts.

See:

Greenhouse Plants, Ornamental - Black Root Rot

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.

See:

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.

Image related to Poinsettia (Euphorbia pulcherrima)-Bacterial Canker

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

OSU Plant Clinic Image, 2014.

Elongate cankers on the stems may be discolored and crack.

OSU Plant Clinic Image, 2014.

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

OSU Plant Clinic Image, 2014.

See:

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.

Brown rot blossom blight on purple leaf plum.

Robin Rosetta, 2009.

Shoot dieback and dead flowers due to brown rot.

Jay W. Pscheidt, 2007.

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

Robin Rosetta, 2009.

Go to:

Prune and Plum (Prunus spp.)

See:

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.

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.

This is a typical gall produced by this disease.

Photo by Everett Hansen, 1999.