Plant Disease Management Handbook

Air Pollution (Ozone)

Smoke can be seen during the Columbia gorge fire of 2017. Particulates in smoke are not harmful to plants as they are to humans.

Jay W. Pscheidt, 2017.

Ozone damage to Jeffery pine (Pinus jeffreyi) shows here as small chlorotic flecks on the needles.

David Shaw, 2012.

Chlorotic spots on onion leaves due to ozone damage.

OSU Plant Pathology slide collection.

The leaf damage is unknown but ozone is suspected due to the distribution of symptoms on plants and leaves. Note the damage is worse on the upper leaf surface and between veins.  

OSU Plant Clinic image, 2012.

close up of grape leaf

Unknonw grape cultivar with angular dark spots on the top side of older leaves due to ozone. Viognier grape is sensative to ozone.

2021.

Sarcococca spp. experienced significant green leaf drop over a few days after the heavy smoke event of 2020.

OSU Plant Clinic, 2020.

Cause Sphaerulina taxi, a fungus that has been reported from all states and considered common in Washington. A problem when yew is used as a hedge.

Symptoms The needles of the current season are killed. Infected needles become light green and finally grayish or reddish brown. The upper surface of an infected needle is covered with minute black fruiting bodies (perithecia) of the fungus. The infected needles are cast.

See:

Tree Wound Paints

A species of Gymnopilus fruiting on Salix scouleriana.

Jay W. Pscheidt, 2021.

A species of Gymnopilus fruiting on Salix hookeriana.

Jay W. Pscheidt, 2021.

A Ganoderma applanatum conk from a willow which indicates the presence of a white rot in the tree.

OSU Plant Clinic image, 2015.

See:

Cherry (Prunus spp.) - Silver Leaf

See:

Willow (Salix spp.) - Marssonina Leaf and Twig Spot

Willow (Salix spp.) - Rust

Black, tar-like thickened spots are produced on the upper leaf surfaces which is smooth and shiny early in the season, but becomes dull black and ridged in the fall.

OSU Plant Clinic image, 2019.

See:

Seed Crop, Crucifers (Brassica, Eruca, and Raphanus spp.) - Downy Mildew (Staghead)

By C. M. Ocamb

Cause The fungus, Phoma destructiva var. destructiva, can infect tomato and peppers and survives in soil or infected plant debris. This fungus can be seedborne in tomato, paprika, and perhaps other crops in the family, Solanaceae. Plant injury, including by insects, enhances infection.

See:

Sword Fern (Polystichum munitum) - Diseases

Upper image is from June 2011 while the lower image from the exact same location is from May 2017. Note lack of sword ferns.

See:

Alyssum - Downy Mildew

Discolored and deformed leaf symptoms due to Peronospora sp.

Melodie Putnam, 2000.

Downy mildew symptoms on top of leaf (top image) and underneath leaf (bottom image).

Photos by Melodie Putnam, 2000.

Cause Sparassis crispa (formerly Sparassis radicata) , a fungus reported to be common in Washington on Engelmann spruce. Can also occur on Douglas-fir, ponderosa pine, white fir, and southwestern white pine. Both heartwood and sapwood are decayed in the roots but only heartwood in the lower trunk. It is not known how the fungus gains entry into the roots but it is not via fire scars or wounds. Tree-to-tree spread appears to be via root grafts or root-to-root contact.

Herbarium specimen - fruiting body of Sparassis radicata collected in 1976 near the Alsea summit in a Douglas-Fir stand.

Jay W. Pscheidt, 2018.

Herbarium specimen - fruiting body of Sparassis crispa collected in 1998 in Douglas county in a Hemlock stand.

Jay W. Pscheidt, 2018.