Nectria Canker

Neonectria ditissima

135 host plants

Last updated

Data Maturity Structured

This profile synthesizes data from multiple published sources. Expert field review is in progress.

In maples, oaks, and ash trees in cool, moist regions, look for slightly sunken lesions on twigs and limbs where wounds have occurred. The true giveaway is the appearance of striking orange-red fungal fruiting bodies clustered across the cankered area, making the problem unmistakable once it develops. Cankers can girdle entire branches or limbs, causing everything beyond them to die. In young trees, this translates to significant branch loss and structural damage.

The practical reality is that timing matters enormously: wounds created in late summer or fall provide entry points when the tree's defense systems are slowing down, so you'll see infection establish over winter and become obvious the following growing season. The management take-home is to prune only during dry weather near the end of dormancy, never in fall, and make clean cuts that heal promptly without leaving stubs where fungi can establish.

Quick Reference

Causal Agent
Neonectria ditissima
Host Plants
135
Spread
wind
Favorable Conditions
Cool, wet weather with high humidity and frequent rainfall (fall, winter, spr...

Management

Vulnerability Window

Dormant season through bud break (BBCH 97–09, approximately October–May in Western Washington). Peak infection risk during fall rains and spring moisture. Avoid pruning during late summer and fall when wounds cannot compartmentalize quickly; prune only during dry weather in late dormancy (March–April in Puget Sound region) when rapid callus formation begins.

What Triggers Infection

Cool, wet weather with high humidity and frequent rainfall (fall, winter, spring). Ascospore release requires moisture and occurs during rain events Sept–May. Infection requires fresh wounds and temperatures ≤50°F for initial establishment. Most active during dormant season and early spring when trees cannot effectively callus over wounds. Drought-stressed or frost-damaged trees show increased susceptibility.

Cultural Controls

  • Remove and destroy affected twigs and limbs.
  • Do not leave them on the ground between rows; carry them out to a burn pile or bury them completely into the soil.
  • Prune during dry weather near the end of the dormant period.
  • Avoid wounds.
  • Avoid leaving pruning stubs when removing rootstock top growth.
  • Make a clean cut with a sharp tool, which will heal promptly.

Host Plants (135)

Acer buergerianum Trident Maple, Three-toothed Maple Acer campestre Hedge Maple, Field Maple, Common Maple Acer capillipes Red Stripebark Maple, Red Snakebark Maple, Hakkoda Maple Acer carpinifolium Hornbeam Maple Acer circinatum Vine, Maple Acer coriaceifolium Leatherleaf Maple Acer crataegifolium Hawthorn, Maple Acer davidii David Maple, Père David's Maple Acer freemanii Freeman Maple, Hybrid Red Maple Acer ginnala Acer ginnala Acer glabrum Rocky Mountain Maple, Rock Maple, Douglas Maple, Dwarf Maple Acer glabrum var. douglasii Douglas Maple, Dwarf Maple, Rocky Mountain Maple Acer grandidentatum Bigtooth Maple, Western Mountain Sugar Maple, Rocky Mountain Sugar Maple Acer griseum Paperbark Maple Acer henryi Henry's Maple Acer japonicum Fullmoon Maple Acer macrophyllum Bigleaf Maple Acer maximowiczianum Nikko Maple Acer miyabei Miyabe Maple Acer monspessulanum Montpellier Maple Acer negundo Boxelder Manitoba Maple, Ash-leaved Maple Acer nipponicum Nippon Maple Acer oblongum Evergreen Maple, Smooth Leaf Maple Acer oliverianum Oliver Maple Acer opalus subsp. obtusatum Bosnian Maple Acer palmatum Japanese Maple Acer palmatum var. dissectum Dissected Japanese Maple Acer pensylvanicum Striped Maple, Moosewood Maple Acer pentaphyllum Acer pentaphyllum (no common name) Acer pictum Painted Maple Acer platanoides Norway Maple Acer pseudoplatanus Planetree Maple, Sycamore, Maple Acer rubrum Red Maple Acer rufinerve Redvein Maple, Honshu Maple Acer saccharinum Silver Maple Acer saccharum Sugar Maple Acer sempervirens Cretan Maple Acer shirasawanum Shirasawa Maple Acer spicatum Mountain Maple, Moose Maple Acer tataricum Tatarian Maple, Tartarian Maple Acer tataricum subsp. ginnala Amur Maple Acer tegmentosum Manchurian Stripebark Maple, Manchustriped Maple Acer triflorum Three Flowered Maple Acer truncatum Purpleblow Maple, Shantung Maple Acer velutinum Velvet Maple Alnus alnobetula Circumpolar alder group Alnus alnobetula subsp. crispa American Green Alder, Mountain Alder, Green Alder Alnus alnobetula subsp. sinuata Sitka Alder, Wavy Leaf Alder Alnus cordata Italian Alder Alnus glutinosa Common Alder, European Alder, Black Alder Alnus incana subsp. rugosa Speckled Alder Alnus incana subsp. tenuifolia Thinleaf Alder, Mountain Alder Alnus japonica Japanese Alder Alnus rhombifolia White Alder Alnus rubra Red Alder Alnus rubra f. pinnatisecta Cutleaf Red Alder Alnus sinuata Sitka Alder Fraxinus americana White Ash, American Ash Fraxinus anomala Singleleaf Ash, Dwarf Ash Fraxinus excelsior Euopean Ash, Common Ash Fraxinus latifolia Oregon Ash Fraxinus ornus Flowering Ash Fraxinus oxycarpa Fraxinus oxycarpa Fraxinus pennsylvanica Green Ash Fraxinus quadrangulata Blue Ash Fraxinus sieboldiana Siebold Ash, Japanese Flowering Ash, Chinese Flowering Ash Quercus acutissima Sawtooth Oak Quercus agrifolia Coast Live Oak Quercus alba (Eastern) White Oak Quercus arizonica Arizona Oak, Arizona White Oak Quercus berberidifolia California Scrub Oak, Scrub Oak, Inland Scrub Oak Quercus bicolor Swamp White Oak Quercus bimundorum Two Worlds Oak, Bimundors Oak Quercus castaneifolia Chestnut-leaved Oak, Chestnutleaf Oak, Persian Oak Quercus cerris Turkey Oak Quercus chrysolepis Canyon Live Oak Quercus coccinea Scarlet Oak Quercus douglasii Blue Oak, California Blue Oak Quercus durata Leather Oak Quercus emoryi Emory Oak, Black Oak, Blackjack Oak Quercus engelmannii Engelmann Oak, Mesa Oak Quercus frainetto Hungarian Oak, Italian Oak Quercus gambelii Gambel Oak, Rocky Mountain White Oak Quercus garryana Oregon White Oak Quercus garryana var. breweri Brewer's Oak Quercus glandulifera Konara Oak Quercus glauca Japanese Blue Oak, Ring-cupped Oak Quercus hypoleucoides Silverleaf Oak, Whiteleaf Oak Quercus ilex Holly, Oak, Holm Oak Quercus ilicifolia Bear Oak Quercus imbricaria Shingle Oak Quercus kelloggii California Black Oak Quercus leana Lea's Oak Quercus lobata Valley Oak, Roble Oak, California White Oak Quercus macrocarpa Bur Oak, Mossycup Oak Quercus marilandica Blackjack Oak, Jack Oak Quercus mongolica Mongolian Oak Quercus montana Mountain Chestnut, Oak, Chestnut, Oak, Rock Chestnust Oak Quercus muehlenbergii Chinkapin Oak, Chinquapin Oak, Yellow Chestnut, Oak Quercus myrsinifolia Chinese Evergreen Oak, Bamboo-leaf Oak Quercus nigra Water Oak, Possum Oak Quercus palustris Pin Oak, Swamp Spanish Oak Quercus petraea Sessile Oak, Durmast Oak, Irish Oak Quercus phellos Willow, Oak Quercus prinoides Dwarf Chinquapin Oak, Dwarf Chestnut, Oak, Scrub Chestnut, Oak Quercus robur English Oak Quercus rubra Northern Red Oak Quercus sadleriana Sadler Oak, Deer Oak Quercus stellata Post Oak Quercus suber Cork Oak Quercus turbinella Scrub Live Oak Quercus undulata Wavyleaved Oak Quercus vaccinifolia Huckleberry, Oak Quercus velutina Black Oak Quercus virginiana Southern Live Oak, Live Oak Quercus wislizeni Interior Live Oak, Chapparal Oak Rhamnus alnifolia Alder Buckthorn, Glossy Buckthorn, Breaking Buckthorn Robinia neomexicana New Mexican Locust, Southwest Locust, Desert Locust Robinia pseudoacacia Black Locust Sorbus alnifolia Korean Mountain Ash, Alder, Mountain Ash Sorbus aria Whitebeam Mountain Ash Sorbus aucuparia European Mountain Ash Sorbus koehneana Chinese Mountain Ash, White-fruited Chinese Mountain Ash Sorbus poteriifolia Mountain Ash Sorbus scopulina Greene Mountain Ash, Western Mountain Ash Sorbus sitchensis Sitka Mountain Ash, Pacific Mountain Ash, Western Mountain Ash Sorbus yunan Sorbus yunan (no English common name) Ulmus americana American Elm Ulmus davidiana David Elm Ulmus davidiana var. davidiana unknown Ulmus davidiana var. japonica Japanese Elm Ulmus glabra Ulmus glabra Ulmus hollandica Dutch Elm, Holland Elm, Hybrid Elm Ulmus parvifolia Lacebark Elm, Chinese Elm Ulmus pumila Siberian Elm