Plant Disease Management Handbook

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Fir, Douglas (Pseudotsuga menziesii) - Needle Cast, Swiss

Note the irregular pattern on the needles.

Dave Shaw, 2008.

Douglas-fir needles

Many spots coalesce and become deep red-brown with a mottled appearance in spring while new shoots are light green.

David Shaw, 2015.

New shoots look healthy while older needles show infection by Rhabdocline.

David Shaw, 2015.

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Fir, Douglas (Pseudotsuga menziesii) - Upper and Lower Stem Canker (Phoma Blight)

Image related to Fir, Douglas (Pseudotsuga menziesii)-Lower Stem Canker
The bark has been scraped away on this seedling to reveal the discolored cambium found at the ground line.
Photo by Everett Hansen, 1983.

Cause Coniferiporia sulphurascens is a native root pathogen and often found in forested areas, in large old tree stumps where it can live several decades as a saprophyte. Infection spreads from tree to tree through the stand and from stumps to roots of healthy seedlings or trees that contact infected wood. Root infections eventually lead to root and lower bole decay; the tree dies directly or as a result of windthrow. Infected trees may take several years to die, declining slowly over time.

Two people examining decay of tree

Root infections eventually lead to root and lower bole decay.

David Shaw, 2010.

Decayed wood separates at the annual rings giving the disease its name.
Shawn Mcmurtrey, 2020.

Masses of setal hyphae can been seen as a reddish-brown fuzz on the upper part of this decayed wood.

David Shaw, 2006.

Masses of setal hyphae can been seen as a reddish-brown fuzz on the upper center of this picture.

David Shaw, 2006.

Pitted wood that may be seen in the advanced decay, with the oval pits ranging in size from 0.5 - 1mm.
Shawn Mcmurtrey, 2020.

Decay appears as reddish-brown-to-chocolate-brown irregular patches or crescent-shaped stains, usually in the heartwood, on fresh cut stump.

Dr. Anna Leon, 2020.

Trees die directly or as a result of windthrow.

David Shaw, 2017.

Close up of forest from space.

Satellite imagery of root disease pockets or gaps within the forest due to laminate root rot near Waldo Lake, OR.

Image courtesy of Shawn McMurtrey captured using Google Earth.

Cause In most container and bareroot nurseries, the genus Fusarium is ubiquitous in nursery soils, on seeds of several conifer species, and on healthy and diseased conifer seedlings, especially Douglas-fir, western white pine (Pinus monticola), and ponderosa pine. Fusarium commune, however, is the primary species of Fusarium associated with root disease in conifers.

Image related to Fir, Douglas and True-Hypocotyl Rot and Root Rot

Rotted roots yielded Phytophthora, Pythium as well as Fusarium species from these seedlings. Also note height differences across the plants.

OSU Plant Clinic Image, 2014.

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Greenhouse Plants, Ornamental - Gray Mold

Image related to Fir, Douglas (Pseudotsuga menziesii)-Gray Mold
The plant on the right has dead foliage and some moldy growth after storage.
Photo by Everett Hansen, 1980.

These new shoots have died from this disease.

Photo by Melodie Putnam, 1990.

Yes, this is a Douglas-fir with Botrytis sp.

Photo by Melodie Putnam.

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Oak (Quercus spp.) - Mistletoe (a True Mistletoe)

Image related to Fir, Douglas and True-Dwarf Mistletoe
Dwarf mistletoe infection is becoming noticeable on these Douglas-fir branches. Note the browish male stems of the mistletoe among the green needles.
Photo by Everett Hansen, 1980.
Image related to Fir, Douglas and True-Dwarf Mistletoe
Douglas-fir with large mistletoe brooms.
Photo by Everett Hansen, 1999.

Occasionally large brooms may form on Douglas-fir with no apparent cause.

Jay W. Pscheidt, 2020.

Image related to Fir, Douglas and True-Dwarf Mistletoe
Not all brooms are due to dwarf mistletoe. This unknown growth occurred on Douglas-Fir in the Portland area where dwarf mistletoe is not know to occur.
OSU slide collection, 2009.

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Fir, Douglas and True - Hypocotyl Rot and Root Rot

Spruce (Picea spp.) - Cylindrocarpon Root Rot

Image related to Fir, Douglas and True-Damping-off

Douglas-fir seedling wilting due to infection with Pythium irregulare.

Jerry Weiland, 2012.
Image related to Fir, Douglas and True-Damping-off

Douglas-fir seedling with Pythium irregulare. Note wire stem symptom near ground line and algal growth on media indicating very wet conditions.

Jerry Weiland, 2012.
Image related to Fir, Douglas and True-Damping-off

Douglas-fir with Pythium irregulare (healthy plant on left, 3 diseased plants on right).

Jerry Weiland, 2012.

Cause The fungus Leptographium wageneri var. pseudotsugae in young Douglas-fir stands west of the Cascade Range that have been thinned (especially in the interior areas of southwest Oregon) and Grosmannia wageneri (formerly L. wageneri var. ponderosum) on old ponderosa pine stands east of the Cascade Range.

Image related to Fir, Douglas (Pseudotsuga menziesii)-Black-Stain Root Disease

Symptoms in xylem of four year old Douglas-fir seedling infected by the blackstain root disease fungus. Bark has been stripped to show black vascular streaking.

Jared LeBoldus, 2016.

Cause Armillaria ostoyae (may be referred to as A. solidipes in some publications) is the species associated with most conifer mortality in the Pacific Northwest, while A. mellea is considered rare.

Mycelial fans are thick, white layers of fungus that adhere to the inner root bark and/or the wood beneath the bark. This tree was found in a Laminated root rot center.

Jay W. Pscheidt, 2018.

Root rots are characterized by thin and/or chlorotic foliage and dieback of the crown.

Jay W. Pscheidt, 2018.

Notice the black rhizomorphs all over this log.

OSU Extension Plant Pathology Slide Collection.

The thick white plaques or fans of this fungus are found between the bark (phloem) and the wood (xylem).

Jay W. Pscheidt, 2018.

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Hazelnut (Corylus avellana)