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jack weeds

Jack weeds

Preferred habitat

In Victoria, spiny emex occurs in small patches of limited distribution in lowland grassland and grassy woodland areas. It is common along the Murray River irrigation areas as well as in some cereal growing districts and town areas.
Spiny emex leaves are triangular to ovate, 3-12 cm long and 2-10 cm wide. They are mostly hairless with undulate margins.

Spines from spiny emex can cause discomfort and inconvenience to humans, particularly when bare-footed.
Growth calendar
Catchment management authority boundaries
Infestations of spiny emex can be very dense. The fruit is well equipped for dispersal. No matter how it lies on the ground one spine always points upwards, attaching it to almost anything which passes over or is placed on it, particularly shoes, rubber tyres, feet of animals or containers of produce.
The icons on the calendar below represent the times of year for flowering, seeding, germination, the dormancy period of Spiny emex and also the optimum time for treatment.

Parsons, W.T. and Cuthbertson, E.G. 2001, Noxious weeds of Australia, 2nd edn, Inkata Press, Melbourne & Sydney.

Spiny emex Common name: spiny emex Scientific name: Emex australis Steinh. Other scientific name/s: Other common name/s: three-corner jack, double gee

Spiny emex is a low growing annual herb with stems up to 80 cm long, and to 40 cm high. It has woody fruit with spines.

Spiny Emex spreads by seed. The spines on the fruit attach to shoes, tyres, and the feet of animals. The fruit can float and are spread in waterways and flood waters.
Spiny emex is native to South Africa.

A weevil (Perapion neofallax) was released and has become established at a few sites, but unfortunatley as had no impact on controlling spiny emex.
It is also spread in contaminated produce including lucerne hay, clover seed and feed wheat.
See Using herbicides for more information.
Spiny emex grows in all parts of NSW except the northern and southern tablelands and the far south coast. It grows mainly on lighter sandy soils but can thrive on heavier soils that retain water.
Glyphosate 360 g/L (Roundup®)
Rate: 2.0–3.0 L/ha
Comments: Boom spray. Young, actively growing plants.
Withholding period: Nil.
Herbicide group: M, Inhibitors of EPSP synthase
Resistance risk: Moderate

Glyphosate 360 g/L (Roundup®)
Rate: 500–700 mL per 100 L of water
Comments: Spot spray.
Withholding period: Nil.
Herbicide group: M, Inhibitors of EPSP synthase
Resistance risk: Moderate

Spiny emex ( Emex australis ) Profile Control Biosecurity duty Profile How does this weed affect you? Spiny emex is a serious weed of crops and pastures. It is a vigorous,