Plant Disease Management Handbook

Cause The fungus Golovinomyces sp. (possible G. oronii or G. vincae) was found on Vinca minor plants in western Oregon in 2019. Disease distribution was on leaves of landscape plants under eves of a home. Plants in the open or under cedar trees were not obviously infected.

Thin, white to gray mycelial mats or colonies were seen on both leaf surfaces.

Jay W. Pscheidt, 2019.

Thin, white to gray mycelial mats or colonies were seen on both leaf surfaces.

Jay W. Pscheidt, 2019.

See:

Tomato (Solanum lycopersicum) - Fusarium Wilt (Fusarium Foot Rot)

Tomato (Solanum lycopersicum) - Varietal Resistance

By M. Nampijja, S. Crane, L. du Toit, and C. Ocamb

Bacterial leaf spot caused by Pseudomonas syringae pv. aptata in baby leaf Swiss chard crops. Photo credited to M. Nampijja, S. Crane, and L. du Toit, Washington State University.
Bacterial leaf spot caused by Pseudomonas syringae pv. aptata in baby leaf Swiss chard crops. Photo credited to M. Nampijja, S. Crane, and L. du Toit, Washington State University.

Bacterial leaf spot caused by Pseudomonas syringae pv. aptata in baby leaf Swiss chard crops.

Photo credited to M. Nampijja, S. Crane, and L. du Toit, Washington State University.

By M. Nampijja, S. Crane, L. du Toit, and C. Ocamb

Bacterial leaf spot caused by Pseudomonas syringae pv. aptata in red beet crops. A) Severe, coalesced lesions on a leaf. B) Bacterial leaf spot symptoms on leaves and seed stalks (black arrow) in a table beet seed crop. C) Bacterial leaf spot symptoms on beet seedlings. D) Dark black, water-soaked lesions on a beet leaf following a rainstorm.

Photo credited to M. Nampijja, S. Crane, and L. du Toit, Washington State University.

See:

Spruce (Picea spp.) - Phytophthora Root Rot

Cause Fusarium sp. is suspect. Fusarium oxysporum was found repeatedly during 2012 and 2013 in association with dying plants in Oregon seed fields. The fungus is soilborne and can survive in soil, often in plant debris, for at least several year as durable resting spores known as chlamydospores. The fungus can be spread by infested equipment or windborne or waterborne movement of infested soil.

See:

Apple (Malus spp.) - Scab

See:

Peach (Prunus persica) - Powdery Mildew

The development of rusty spot symptoms from young lesions to russetted fruit, left to right.

Norm Lalancette, 2016.  

See:

Cedar, Port-Orford (Chamaecyparis lawsoniana) - Root Rot

Microbiota decussata (Russian cedar) with die-back due to Phytophthora root rot.

Oregon State University Plant Clinic image, 2016.

Cause The fungus Cryptostroma corticale has been causing dieback primarily in sycamore maples (Acer pseudoplatanus), although several other species can also become infected. The disease has been found in eastern WA for many years and in 2020 in the Seattle area on sycamore maple, red maple (Acer rubrum), Japanese maple (A. palmatum), vine maple (A.

Low resolution images showing that bark sloughs away exposing dark patches of the fungal stroma and powdery spores.

Gary Chastagner.

Another low resolution image showing that trees may have a greenish-brown-to-greenish-yellow stain of the wood that can be seen when an infected branch is cut into cross-section.

Gary Chastagner.