Noogoora bur (Xanthium strumarium) was probably accidentally introduced to New Zealand in maize seed. It is a pastoral pest, inhabiting warm temperate regions on disturbed and fertile soil.
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The seeds are poisonous to stock, particularly pigs and cattle. The fruit (small woody 'burs') are easily entangled in sheep’s wool and can decrease fleece quality. Burs can also compete with pasture species and carry some fungal diseases capable of infecting horticultural plants.
What it looks like
Noogoora bur is an annual herb. Burs are easily dispersed in wool as they attach with hooked spines. They have air pockets around the spines which assist in travel by water. They are also commonly spread in agricultural seeds, road gravel and farm equipment. Bathurst bur (Xanthium strumarium) is a relative of noogoora bur also found in New Zealand which is considered to be a nuisance pasture pest. Land occupiers are encouraged to control Bathurst bur wherever it occurs on their property.
Noogoora bur is a coarse plant with broad serrated leaves and branching stems which grow up to 1.5 metres high. It has two growth forms, either erect and single stemmed, or very branched and spreading.
Leaves: Dark green, three-lobed and similar in shape to grape leaves.
Flowers: Inconspicuous and the fruit are woody, brown, egg-shaped burs.
Stems: Blotched purple and covered in short coarse hairs.
Seeds: Grow in clusters and are covered in hooked spines. Each bur contains two seeds and each plant can produce up to 11,000 seeds.
Where you can find it
The main infestations of noogoora bur and Bathurst bur in the Waikato region are in the cropping area of the Matamata-Piako and Hauraki Districts.
Responsibility for control
Waikato Regional Council undertakes control of noogoora bur in the Waikato region. Our Regional Pest Management Strategy aims to contain current infestations and undertake an eradication programme to ensure no further infestations occur.
Noogoora bur is also banned from sale, propagation, distribution and commercial display. Please notify Waikato Regional Council if you find noogoora bur in the Waikato region.
Controlling noogoora bur and bathurst bur
Mowing or rotary slashing may give effective control, however it must be carried out before burs are formed. Little is achieved by cutting the plants after burs have been formed unless the plants are gathered and destroyed, preferably by burning.
Chemical control is effective, especially on young plants. Plants must be treated before any burs are formed to ensure seeding is prevented. `Blanket’ spraying is effective, either by boom spray, aerial spray or mist spraying techniques, provided the correct application rates of chemicals are used.
Advice on the most suitable herbicides available for control of these plant pests can be obtained from your Biosecurity Plant Pest Contractor.
Note: Some chemicals used to control burs may also cause damage to nearby plants. Contact your Biosecurity Plant Pest Contractor to ensure you are carrying out the best control programme for your situation.
Re-sowing grazing areas after plants have been removed is essential to prevent re-invasion.
For further information and advice contact your local Biosecurity Plant Pest Contractor.
- Visit our Waikato Regional Pest Management Strategy.
- 'What makes a pest a pest? - A guide to Waikato's pest management future' download, order or pick up for free from our offices.
- 'Plant me instead - Plants to use in place of common pest plants'. Pick up or order for free from our offices.
- Download the National Pest Plant Accord.
- 'Poisonous plants and fungi in New Zealand - A guide for parents, schools and child minders'. Pick up or order for $15 from our offices.