Urban Trees Attract Ameliorable if not Avoidable Prominent Diseases

Summary: Urban trees attract ameliorable if not avoidable prominent diseases, according to the hour-long Urban Forestry Today webinar Thursday, Nov. 3, 2022.

American elm (Ulmus americana) trees, also acknowledged as water elm and white elm, are perhaps the commonest association by tree lovers of prominent diseases, such as Dutch elm disease, elm yellows and verticillium wilt, that afflict urban trees. The Oklahoma City National Memorial assigns survivalistic abilities to the elm tree that astounded all audiences with its blooming within a year of the Oklahoma City bombing of the Alfred P. Murrah Federal Building in Oklahoma City OK April 19, 1995; Saturday, Sep. 18, 2004, 09:38, image of The Survivor Tree elm: Dustin M. Ramsey (Kralizec!), Public Domain (CC0 1.0 Universal), via Wikimedia Commons

Urban trees attract ameliorable if not avoidable prominent diseases, according to Prominent Diseases of Trees in the Urban Environment, an Eastern noon-hour-long, monthly webinar through UMass Amherst Extension Thursday, Nov. 3, 2022.

Dr. Rick W. Harper, University of Massachusetts Amherst Extension Professor, brings about monthly broadcasts bearing one International Society of Arboriculture and 0.5 Massachusetts certified arborist credits. Fellow Professor Dr. Nicholas Brazee commenced comparing diverse-specied, organic-mattered Quabbin Reservoir natural and, with natural defenses abiotically stressed, monocultural, soil-, sun-, water-, wind-compromised Minneapolis urban forests. SUNY-ESF (State University of New York College of Environmental Science and Forestry) Professor Dr. Paul D. Manion previously designated factors contributing to, inciting, predisposing decline spirals.

Contributing and inciting factors respectively encompass canker fungi, wood-borers, bark-borers, Armillaria root rot, saprobic decay and nematodes; defoliators, excavation, drought, excessive salt, frost and air pollution.

Predisposing factors feature urban environment, soil compaction, poor fertility, non-native range, salt, low soil moisture-holding capacity, poor soil drainage, climate change, air pollution and old age.

Abiotic stress, climate change and 20th- and 21st-century lacks of species diversity perhaps generated disease outbreaks, such as Dutch elm disease of Ulmus and Zelkova genera. Norway maple (Acer platanoides) heads replanting lists of American elm (Ulmus americana) successors even as tar spot (Rhytisma acerinum) harries it, not red maple (Acer rubrum). Dr. Brazee includes among canker fungi Botryosphaeria canker, coral-spot canker (Nectria cinnabarina), Diplodia shoot tip blight and canker (Diplodia sapinea) and Phomopsis stem and branch canker.

Deathly defoliators, nematodes, viruses and wood- and bark-borers and prominent diseases from wood-decay fungi jeopardize urban trees in compacted, droughty, excavated, infertile, polluted, salty, waterlogged soils.

Knowing about prominent diseases of urban trees kindles knowing about fusarium wilt (Fusarium oxysporum), laccate (lacquer-like, wax-covered) and non-laccate Ganoderma species and powdery mildew (Erysiphe platani).

Botryosphaeria pathogens leave urban trees, already moisture-, nutrient-, pest-, pollution-, sun-, temperature-, wind-stressed or weakened, with black-spotted, canker-girdled, sap-oozing, split-bark, water-starved branch dieback and dying leaves. Diplodia shoot tip blight and canker may mob pest-weakened, stressed, weather-, wind-, work-wounded coniferous trees and muster blighted, stunted, wilted needles and cankered, resin-marred branch dieback. Phomopsis canker nestles inside current-year buds or pest-, weather-, wind-, or work-stressed or weakened wounds or present-year shoots on coniferous and hardwood branches and smaller-diameter stems.

Botryosphaeria-overwhelmed crabapple (Malus), Diplodia-overwhelmed red oak (Quercus rubra), Phomopsis-overwhelmed Japanese maple (Acer palmatum), blue (Piceea pungens) and Norway spruce (Picea abies) urban trees obtain prominent diseases.

Dr. Brazee presents coral-spot (Nectria cinnabarina) pestering with canker-girdling, slough-bark dieback and early-dropped, sparse, undersized foliage large-diameter, weather-, wind-, work-wounded Japanese and trident (Acer buergerianum) maple.

Thyronectria austroamericana canker quests black locust (Robinia pseudoacacia), honeylocust (Gleditsia triacanthos), Kentucky coffeetree (Gymnocladus dioicus) and mimosa (Albizia julibrissin) for its dark-fruiting asexual and sexual bodies. Oak lateral root- and trunk base-residing conks of artist’s conk (Ganoderma applanatum) wood-decaying fungi sometimes and reishi-mushroom (Ganoderma sessile) wood-decaying fungi frequently reveal extensive internal decay. Dr. Brazee shows fusarium wilt (Fusarium oxysporum) and sycamore powdery mildew (Erysiphe platani) respectively dark-staining fragrant sumac (Rhus aromatica) and white-staining London planetree (Platanus x acerifolia).

Toning low-pollution, low-salt soil moisture and nutrients, triggering native species diversity and trimming dead canopies turn urban trees away from ameliorable if not avoidable prominent diseases.

Norway maple (Acer platanoides) trees are appearing in the American niches once associated with American elms even as red maple (Acer rubrum) trees, also acknowledged as soft maple, swamp maple and water maple, are central and eastern North American natives and are not susceptible to giant tar spot; J.C. Loudon, Arboretum et Fruticetum Britannicum, vol. V, plate 29: Internet Archive Book Images, Public Domain, via Wikimedia Commons

Acknowledgment

My special thanks to talented artists and photographers/concerned organizations who make their fine images available on the internet.

Image credits:

American elm (Ulmus americana) trees, also acknowledged as water elm and white elm, are perhaps the commonest association by tree lovers of prominent diseases, such as Dutch elm disease, elm yellows and verticillium wilt, that afflict urban trees. The Oklahoma City National Memorial assigns survivalistic abilities to the elm tree that astounded all audiences with its blooming within a year of the Oklahoma City bombing of the Alfred P. Murrah Federal Building in Oklahoma City OK April 19, 1995; Saturday, Sep. 18, 2004, 09:38, image of The Survivor Tree elm: Dustin M. Ramsey (Kralizec!), Public Domain (CC0 1.0 Universal), via Wikimedia Commons @ https://commons.wikimedia.org/wiki/File:The_Survivor_Tree_at_the_Oklahoma_City_National_Memorial.jpg

Norway maple (Acer platanoides) trees are appearing in the American niches once associated with American elms even as red maple (Acer rubrum) trees, also acknowledged as soft maple, swamp maple and water maple, are central and eastern North American natives and are not susceptible to giant tar spot; J.C. Loudon, Arboretum et Fruticetum Britannicum, vol. V, plate 29: Internet Archive Book Images, Public Domain, via Wikimedia Commons @ https://commons.wikimedia.org/wiki/File:Arboretum_et_fruticetum_britannicum;_or,_The_trees_and_shrubs_of_Britain,_native_and_foreign,_hardy_and_half-hardy,_pictorially_and_botanically_delineated,_and_scientifically_and_popularly_described;_(19750331845).jpg; Internet Archive Book Images, Public Domain, via Flickr @ https://www.flickr.com/photos/internetarchivebookimages/19750331845/; Not in copyright, via Internet Archive @ https://archive.org/details/arboretumetfruti05loud/page/57/mode/1up

For further information:

Brazee, Nicholas. "Botryosphaeria Canker." University of Massachusetts Amherst > Center for Agriculture, Food, and the Environment > UMass Extension Landscape, Nursery and Urban Forestry Program > Publications & Resources > Fact Sheets > Diseases > Stem & Branch & Trunk Cankers. Last updated January 2018.
Available @ https://ag.umass.edu/landscape/fact-sheets/botryosphaeria-canker

Brazee, Nicholas. "Coral-spot Nectria Canker." University of Massachusetts Amherst > Center for Agriculture, Food, and the Environment > UMass Extension Landscape, Nursery and Urban Forestry Program > Publications & Resources > Fact Sheets > Diseases > Stem & Branch & Trunk Cankers. Last updated March 2018.
Available @ https://ag.umass.edu/landscape/fact-sheets/coral-spot-nectria-canker

Brazee, Nicholas. "Diplodia Blight." University of Massachusetts Amherst > Center for Agriculture, Food, and the Environment > UMass Extension Landscape, Nursery and Urban Forestry Program > Publications & Resources > Fact Sheets > Diseases > Stem & Branch & Trunk Cankers. Last updated February 2018.
Available @ https://ag.umass.edu/landscape/fact-sheets/diplodia-blight

Brazee, Nicholas. "Dutch Elm Disease." University of Massachusetts Amherst > Center for Agriculture, Food, and the Environment > UMass Extension Landscape, Nursery and Urban Forestry Program > Publications & Resources > Fact Sheets > Diseases > Vascular Wilts. Last updated January 2017.
Available @ https://ag.umass.edu/landscape/fact-sheets/dutch-elm-disease

Brazee, Nicholas. "Phomopsis Canker." University of Massachusetts Amherst > Center for Agriculture, Food, and the Environment > UMass Extension Landscape, Nursery and Urban Forestry Program > Publications & Resources > Fact Sheets > Diseases > Stem & Branch & Trunk Cankers. Last updated December 2017.
Available @ https://ag.umass.edu/landscape/fact-sheets/phomopsis-canker

Brazee, Nicholas. "Tar Spot of Maple." University of Massachusetts Amherst > Center for Agriculture, Food, and the Environment > UMass Extension Landscape, Nursery and Urban Forestry Program > Publications & Resources > Fact Sheets > Diseases > Leaf Spots & Blotches & Blights. Last updated November 2017.
Available @ https://ag.umass.edu/landscape/fact-sheets/tar-spot-of-maple

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Available @ https://ag.umass.edu/landscape/fact-sheets/powdery-mildew

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