Fraxinus pennsylvanica (American ash)

Botanical name

Fraxinus pennsylvanica

Other names

American ash, Canadian ash, Green ash, Red American ash, Red ash , White ash

Genus

Fraxinus Fraxinus

Species

F. pennsylvanica - F. pennsylvanica is a vigorous, spreading, deciduous tree with pinnate leaves divided into five to nine, ovate to lance-shaped, pointed, olive-green leaflets turning yellow in autumn. Clusters of small, purple flowers in spring are followed on female trees by slender, winged, green fruit ripening brown.

Foliage

Deciduous

Habit

Spreading

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Colour

Flower

Purple in Spring

Foliage

Olive green in Spring; Olive green in Summer; Yellow in Autumn

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How to care

Watch out for

Pests

Generally pest-free

Diseases

Ash dieback.

General care

Pruning

Pruning group 1

Propagation

Tends to self-seed freely in ideal growing conditions. Sow seed in autumn in an open frame. Can be sown in spring after chilling in a refrigerator for 2-3 months.

Propagation methods

Seed, Grafting

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Monthly care advice

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Where to grow

Fraxinus pennsylvanica (American ash) will reach a height of 20m and a spread of 20m after 20-50 years.

Suggested uses

Low Maintenance, Foliage only, Coastal, Woodland

Cultivation

Grow in fertile, moist but well-drained, neutral to alkaline soil in full sun. Will tolerate a wide range of conditions. Autumn colour often varies considerably from year to year.

Soil type

Chalky, Clay, Loamy, Sandy (will tolerate most soil types)

Soil drainage

Moist but well-drained, Well-drained

Soil pH

Alkaline, Neutral

Light

Full Sun

Aspect

North, South, East, West

Exposure

Exposed, Sheltered

UK hardiness Note: We are working to update our ratings. Thanks for your patience.

Hardy (H4)

USDA zones

Zone 9, Zone 8, Zone 7, Zone 6, Zone 5, Zone 4, Zone 3

Defra's Risk register #1

Plant name

Fraxinus pennsylvanica (American ash)

Common pest name

Alfalfa dwarf; Anaheim disease; California vine disease; Dwarf disease of alfalfa; Dwarf disease of lucerne; Leaf scald of oleander; Leaf scald of plum; Leaf scorch; Phony disease of peach; Pierce's disease of grapevine; Variegated chlorosis of citrus

Scientific pest name

Xylella fastidiosa subsp. multiplex

Type

Bacterium

Current status in UK

Absent

Likelihood to spread to UK (1 is very low - 5 is very high)

3

Impact (1 is very low - 5 is very high)

4

General biosecurity comments

A bacterial disease with a wide host range detected in Corsica. Although EU regulated; there remains some concern about the risk of introduction. This subspecies is known to be able to thrive in cooler climates. Should an outbreak occur; there would be a need for eradication action which would result in environmental and social impacts.

Defra's Risk register #2

Plant name

Fraxinus pennsylvanica (American ash)

Common pest name

Ash yellows

Scientific pest name

Candidatus Phytoplasma fraxini

Type

Phytoplasma

Current status in UK

Absent

Likelihood to spread to UK (1 is very low - 5 is very high)

2

Impact (1 is very low - 5 is very high)

4

General biosecurity comments

Pathogen causing phytoplasma disease of certain tree species in the Americas. EU regulation already provides some mitigation against the risk of introduction; but could be further strengthened.

Defra's Risk register #3

Plant name

Fraxinus pennsylvanica (American ash)

Common pest name

Asian longhorn beetle; Starry sky beetle

Scientific pest name

Anoplophora glabripennis

Type

Insect

Current status in UK

Absent

Likelihood to spread to UK (1 is very low - 5 is very high)

2

Impact (1 is very low - 5 is very high)

4

General biosecurity comments

Recognised threat to a wide range of deciduous tress native to the UK. Already regulated it is a priority for continued surveillance and statutory action. The risk of entry is further mitigated by EU legislation requiring the monitoring of wooden packaging material originating from China.

About this section

Our plants are under greater threat than ever before. There is increasing movement of plants and other material traded from an increasing variety of sources. This increases the chances of exotic pests arriving with imported goods and travellers, as well as by natural means. Shoot is working with Defra to help members to do their part in preventing the introduction and spread of invasive risks.

Traveling or importing plants? Please read "Don't risk it" advice here

Suspected outbreak? Click here for contact details to report to the relevant authority.

Date updated: 7^th March 2019 For more information visit: https://planthealthportal.defra.gov.uk/