Plant Disease Management Handbook

Cause Leaf spots are common on lemon balm grown in PNW gardens but little work has been done on these problems. None have been formally reported in the PNW but the OSU Plant Clinic has found Phyllosticta and TSWV on the few samples that have been sent in. The fungi Phyllosticta decidua (now named Boeremia exigua var.

Cause Unknown. Not a common problem but found sporadically on Ennis (1990s), Jefferson (2010s) and Wepster (2020s) trees over the last few decades. Affected trees were neither considered juvenile nor mature but tended to be 5 to 10 years old on average. Affected branches do not yield any specific fungi, bacteria or viruses when sent to OSU Plant Clinic. Trees are not consistently associated with cankers, root rots or insect borers.

Cause Plenodomus lingam (syn. Leptosphaeria maculans, anamorph: Phoma lingam) and Plenodomus biglobosus (syn. Leptosphaeria biglobosa) are fungi that can infect a range of cruciferous crops.

See:

Squash (Cucurbita spp.) - Toxic Squash (Toxic Zucchini)

See:

Squash (Cucurbita spp.) - Toxic Squash (Toxic Zucchini)

Cause Plenodomus lingam (syn. Leptosphaeria maculans, anamorph: Phoma lingam) and Plenodomus biglobosus (syn. Leptosphaeria biglobosa) are fungi that can infect a range of cruciferous crops.

Cause Butterfly bushes (Buddleja sp.) are generally disease free, however, a few pathogens have been found in the PNW. The leaf spot disease caused by Cladosporium herbarum has been reported from Washington and found by the OSU Plant Clinic.

See:

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

The OSU Turfgrass Disease Diagnosis Laboratory provides quick and accurate diagnostic information and management recommendations for turfgrass problems. This diagnostic lab supports golf courses, commercial turfgrass managers, and homeowners.

Diagnostic services include: visual diagnosis, microscopic examination, pathogen culturing, disease management recommendations, diagnostic results via phone or email, and a full diagnostic report available with an additional fee.

Pathogen identification by DNA sequencing

Oregon samples: $128/sample.

Out-of-state samples: $189/sample.

Bacterial or fungal cultures that are purified will be identified by sequencing a single DNA region (e.g. ITS or 16S). Identification to species will be provided when possible, but it may be limited to genus depending on the organism.