Acer campestre 'William Caldwell' (Field maple 'William Caldwell')

Botanical name

Acer campestre 'William Caldwell'

Other names

Field maple 'William Caldwell', Hedge maple 'William Caldwell', Common elder 'William Caldwell', Dog oak 'William Caldwell', Maser tree 'William Caldwell', Master tree 'William Caldwell'

Genus

Acer Acer

Variety or Cultivar

'William Caldwell' _ 'William Caldwell' is a columnar, deciduous tree bearing palmate, dark-green leaves turning red and orange in autumn and upright clusters of small green flowers in spring followed by winged fruit.

Foliage

Deciduous

Habit

Broadly columnar

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Colour

Flower

Yellow-green, Insignificant or absent in Spring

Foliage

Variegated, Grey-green, Cream in Summer; Golden-yellow in Autumn

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How to care

Watch out for

Specific pests

Aphids , Horse chestnut scale , Caterpillars

Specific diseases

Verticillium wilt , Coral spot , Honey fungus , Tar spot

General care

Pruning

Pruning group 1. Prune in late autumn to midwinter only.

Propagation methods

Grafting, Budding

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Monthly care advice

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Where to grow

Acer campestre 'William Caldwell' (Field maple 'William Caldwell') will reach a height of 10m and a spread of 3m after 10-20 years.

Suggested uses

Cottage/Informal, Coastal, City, Architectural, Foliage only, Low Maintenance

Cultivation

Grow in fertile, moist but well-drained soil in full sun or partial shade.

Soil type

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

Soil drainage

Moist but well-drained

Soil pH

Neutral

Light

Partial Shade, Full Sun

Aspect

North, South, East, West

Exposure

Exposed

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

Hardy (H4)

USDA zones

Zone 8, Zone 7, Zone 6, Zone 5, Zone 4

Defra's Risk register #1

Plant name

Acer campestre 'William Caldwell' (Field maple 'William Caldwell')

Common pest name

Apple root knot nematode

Scientific pest name

Meloidogyne mali

Type

Nematode

Current status in UK

Unknown

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

UK (along with certain other European countries) received potentially infested trees in 1992; but these were destroyed at the end of the trial period and targeted surveillance has failed to find any trace of the nematode. Main impacts are on elm; apple and mulberry and industry should source such material carefully.

Defra's Risk register #2

Plant name

Acer campestre 'William Caldwell' (Field maple 'William Caldwell')

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 #3

Plant name

Acer campestre 'William Caldwell' (Field maple 'William Caldwell')

Common pest name

Scientific pest name

Hylesia nigricans

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

South American moth which could be damaging to broadleaf species if introduced to the UK; as well as having human health impacts. The main pathway is likely to be goods (including non-plant material) imported from South America and awareness raising with the main industry sectors is recommended.

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/