Plant Disease Management Handbook

See:

Apple (Malus spp.) - Nectria Twig Blight (Coral Spot)

Cankers appear as slightly sunken areas generally associated with wounds.

Melodie Putnam, 1997.

Image related to Maple (Acer spp.)-Nectria Canker

Close up of fruiting bodies on this vine maple.

Lyle J. Feilmeier, Collier Arbor Care, 2006.

Small fruiting bodies of Nectria sp. on this Japanese maple.

OSU Plant Clinic image, 2012.

Nectria sp. fruiting bodies on this full-moon maple.

OSU Plant Clinic image, 2011.

Note the numerous, small, pinkish fruiting bodies of the fungus along this branch.

Photo by Iain MacSwann, 1989.

See:

Maple (Acer spp.) - Anthracnose

Maple (Acer spp.) - Tar Spots

See:

Maple (Acer spp.) - Bigleaf Maple Decline (Bigleaf Maple Dieback)

Image related to Maple (Acer spp.)-Leaf Scorch

Necrotic areas typically apear on the margins and tips of leaves.

Photo by Ralph S. Byther

Necrotic areas are near the margin and between the veins.

Melodie Putnam, 2009.

Bigleaf maples in this area all had leaf scorch symptoms through out the tree especially on sun exposed leaves.

Jay W. Pscheidt, 2016.

See:

Peach (Prunus persica) - Leaf Curl

Cause Taphrina darkeri, a fungus that may be locally epidemic, has been reported from Oregon on vine maple and Idaho on Rocky Mt. maple.

Cause Pseudomonas syringae pv. syringae, the same bacterium that causes bacterial blight of lilac, fruit trees, and many woody ornamentals. It overwinters on infected plant parts or as an epiphyte on healthy tissue. It spreads with windblown rain, insects, and pruning tools. Bacteria enter through wounds or natural openings. Wound infection during budding may interfere with bud-take.

Oshi Beni Japanese maple normally has red or coral colored bark unless attached by bacterial dieback when it turns black.

Jay W. Pscheidt, 2006.

Transition between diseased tissue above and healthy tissue below of this red maple 'October Glory'.

Larry Moore, 1981.

Leaves of Acer rubrum with Pseudomonas syringae.

Larry Moore slide collection, 1971.

Black bark is due to dieback from Pseudomonas sp. but symptoms alone could also be due to Verticillium wilt.

Jay W. Pscheidt, 2006.

Image related to Maple (Acer spp.)-Bacterial Leaf Spot and Dieback

As shoots die back they first turn black from the bacterial infection then gray as other organisms colonize the dead tissue.

Photo by Jay W. Pscheidt, 1994.

Cause Discula sp. and Aureobasidium apocryptum, fungi. They often are found on many different maple species throughout the Pacific Northwest and are favored by warm, wet springs. Not considered an economic problem in the landscape.