Alyssum idaeum (Madwort )

Botanical name

Alyssum idaeum

Other names

Madwort

Genus

Alyssum Alyssum

Species

A. idaeum - A. idaeum is a mat-forming, woody-based, evergreen perennial with ovate to oblong, hairy, grey-green leaves and short, dense racemes of yellow flowers in spring.

Foliage

Evergreen

Habit

Cushion or Mound Forming

---

Colour

Flower

Yellow in Spring

Foliage

Grey-green in All seasons

---

How to care

Watch out for

Specific pests

Aphids , Flea beetles

Specific diseases

Downy mildew , White blister

General care

Pruning

Trim lightly after flowering to maintain a compact habit.

Propagation

Not easily divided.

Propagation methods

Seed, Softwood cuttings

---

Monthly care advice

---

Where to grow

Alyssum idaeum (Madwort ) will reach a height of 0.15m and a spread of 0.3m after 2-5 years.

Suggested uses

Banks and Slopes, Beds and borders, Coastal, Containers, Cottage/Informal, Edging, Gravel, Rock

Cultivation

Grow in moderately fertile, preferably gritty, well-drained soil in full sun.

Soil type

Chalky, Loamy, Sandy

Soil drainage

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 9, Zone 8, Zone 7, Zone 6

Defra's Risk register #1

Plant name

Alyssum idaeum (Madwort )

Common pest name

Cassava whitefly; Cotton whitefly; Sweet potato whitefly; Tobacco whitefly

Scientific pest name

Bemisia tabaci non-European populations

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)

5

General biosecurity comments

Non-European populations of Bemisia tabaci pose an additional risk to European populations due to the potential for introducing non-European viruses.

Defra's Risk register #2

Plant name

Alyssum idaeum (Madwort )

Common pest name

Cassava whitefly; Cotton whitefly; Sweet potato whitefly; Tobacco whitefly

Scientific pest name

Bemisia tabaci European populations

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

The UK has a protected zone in place for this pest which helps to mitigate the risk of entry and establishment. An EFSA opinion is currently being discussed at the EU Annexes Working Group which recommends further strengthening of the regulation.

Defra's Risk register #3

Plant name

Alyssum idaeum (Madwort )

Common pest name

Lance nematode; Nematode; Lance

Scientific pest name

Hoplolaimus spp.

Type

Nematode

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

Nematode species potentially affecting a wide variety of crops; prohibition of soil likely to mitigate risk substantially; keep under review in light of interceptions or findings should they occur in the EU.

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/