Juglans regia (Common walnut)

Botanical name

Juglans regia

Other names

Common walnut, Juglans sinensis, Welsh nut, French nut, Madeira nut, Persian walnut, Ban-nut tree, English walnut, Black sea walnut

Genus

Juglans Juglans

Species

J. regia - J. regia is a slow-growing, rounded to broadly spreading, deciduous tree with pinnate, aromatic leaves divided into five to seven, ovate to elliptic, glossy, dark green leaflets, bronze-purple when young, and insignificant yellow-green flowers in late spring and early summer followed by spherical, green fruit containing edible nuts.

Native to

Central Asia, Europe, Western Asia

Foliage

Deciduous

Fragrance

The leaves are aromatic when bruised.

Habit

Rounded to broadly spreading

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Colour

Flower

Insignificant or absent, Green in Spring

Foliage

Bronze, Dark-purple in Spring; Dark-green in Summer; Dark-green in Autumn

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How to care

Watch out for

Specific pests

Aphids , Walnut blister mites

Specific diseases

Coral spot , Leaf spot

General care

Pruning

Pruning group 1.

Propagation methods

Grafting, Seed

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Monthly care advice

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Where to grow

Juglans regia (Common walnut) will reach a height of 20m and a spread of 15m after 20-50 Years.

Suggested uses

Foliage only, Low Maintenance, Specimen tree

Cultivation

Plant in any well-drained or moist but well-drained soil in full sun.

Soil type

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

Soil drainage

Moist but well-drained, Well-drained

Soil pH

Acid, 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 7, Zone 6, Zone 5, Zone 4, Zone 3

Defra's Risk register #1

Plant name

Juglans regia (Common walnut)

Common pest name

Canker: butternut

Scientific pest name

Ophiognomonia clavigignenti-juglandacearum

Type

Fungus

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)

5

General biosecurity comments

Recommended for regulation by EPPO. Should be considered for regulation by the EU as other countries at greater threat

Defra's Risk register #2

Plant name

Juglans regia (Common walnut)

Common pest name

Thousand Cankers Disease

Scientific pest name

Geosmithia morbida

Type

Fungus

Current status in UK

Absent

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

4

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

4

General biosecurity comments

Insect and fungal pest which together cause ‘thousand cankers disease’ and mortality of walnut in the US and elsewhere. Black walnut is not widespread in the UK but the main walnut species (Juglans regia) is also susceptible. A watching brief will be maintained on the current outbreak in Italy. Industry should also be aware.

Defra's Risk register #3

Plant name

Juglans regia (Common walnut)

Common pest name

walnut twig beetle

Scientific pest name

Pityophthorus juglandis

Type

Insect

Current status in UK

Absent

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

4

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

4

General biosecurity comments

Insect and fungal pest which together cause ‘thousand cankers disease’ and mortality of walnut in the US and elsewhere. Black walnut is not widespread in the UK but the main walnut species (Juglans regia) is also susceptible. A watching brief will be maintained on the current outbreak in Italy. Industry should also be aware.

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/