Macquarie Valley W.C. & 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 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

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 Weeds Committee & Lachlan Valley Weeds Advisory Committee

St John's Wort

Declarations

Identification

Control Methods

Images