Macquarie Valley & Lachlan Valley W.A.C.

St John's Wort

Botanical Name:

Hypericum perforatum

Other Common Names:

Declarations

Class	Regions
Class 3	Bland Shire Council
Class 4	Cabonne Council,Castlereagh Macquarie County Council,Cootamundra Shire Council,Cowra Shire Council,Dubbo City Council,Forbes Shire Council,Lachlan Shire Council,Mid Western Regional Council,Narromine Shire Council,Orange City Council,Parkes Shire Council,Upper Macquarie County Council,Weddin Shire Council,Wellington Council

Landholder Responsibilities:

Class 4 - growth and spread of the plant must be controlled according to the measures specified in a management plan published by the local control authority and the plant may not be sold, propagated or knowingly distributed. Class 3 - The plant must be fully and continuously suppressed and destroyed

Why Is It Bad?:

St. John's Wort has shown itself to be a significant weed in the group project area by its ability to grow in all climatic and topographical zones. It has also shown itself to become a dominant species, replacing native and improved pastures. St. John's Wort's capacity to replace desirable plant species and its effect on stock health (photosensitization) makes it a threat to agricultural/horticultural production.

Identification

Habit:

Herb

Leaves:

Leaves opposite, sessile with oil glands which appear to be perforations when held up to the light.

Flowers:

Flowers of 5 yellow petals with several stamens occur in 3 bundles.

Fruit:

Fruit is a sticky 3- celled capsule containing many seeds. The long-term viability of St. John's Wort seed can be up to 10 years.

Roots:

Rhizomatous

Control Methods

Manual Removal:

St John�s Wort can reproduce from buds on its roots therefore the entire root structure must be removed.

Chemical Use:

Different situations (e.g., flowering times, chemical choice, surrounding plants) require different methods (e.g. spot spraying, wick wiper).

Fire:

Non-specific, it kills seeds and checks growth.

Slashing & Cutting:

Biological Control:

Agents include two species of Chrysolina beetles, Agrilus hyperici, Gall midge, Aphic chloris, and the St John�s Wort stunt mite.

Grazing:

Practical for steep, inaccessible hill country. Only certain breeds of sheep with enough wool growth or dark coloured cattle should be used.

Cultivation & Scalping:

Smothering:

Solarisation:

Competition:

Perennial pastures provide competition that is essential for long term control, particularly during autumn.

Monitoring:

Successful treatment programs rely on ongoing monitoring of sites. Regrowth and new seedlings can easily become larger infestations if follow-up treatments are not part of the management program.

Macquarie Valley & Lachlan Valley

Weeds Advisory Committees

St John's Wort

Declarations

Identification

Control Methods

Images