|Common name:||hoary cress|
|Scientific name:||Lepidium draba L.|
|Other scientific name/s:||Cardaria draba (L.) Desv.|
|Other common name/s:||white weed|
Catchment management authority boundaries
Regionally prohibited in the North East Catchment
Regionally controlled in the Mallee, Corangamite, Goulburn Broken, West Gippsland, Port Phillip and Western Port Catchments
Restricted in the Wimmera, North Central, Glenelg Hopkins and East Gippsland Catchments
Herbaceous plant - Forb (flowering herbaceous plant - not a grass)
Hoary cress is an erect perennial herb to 75 cm. Aerial growth dies over summer with new growth produced in autumn and spring.
Stems are erect and branch near the top. They are covered with fine downy hairs, are longitudinally ribbed and grow to 75 cm high.
Leaves are usually covered with fine, white hairs giving a hoary appearance.
Leaf margins are entire (smooth or without notches) or irregularly toothed, and undulate.The rosette leaves and lower stem leaves grow to 10 cm long, are ovate to wedge-shaped and stalked. The upper stem leaves grow to 8 cm long and are arranged alternately along branches. They are obovate to oblong in shape and stem-clasping.
Flowers of hoary cress are white and fragrant. They grow to 4-6 mm in diameter, are 4-petalled and numerous in terminal clusters.
Hoary cress fruit are a one or two-seeded, heart-shaped capsule. They grow 2-4 mm long and 3-5 mm wide.They have two compartments in a prominent style and with a conspicuous network of veins on the surface.
Growth and lifecycle
Method of reproduction and dispersal
The spread of hoary cress in paddocks is usually via the movement of root fragments.
Dispersal of the plant occurs by movement of pieces of cut root and seeds adhering to mud or caught in the tines of cultivation equipment. Even very small pieces of root are capable of growing, resulting in the increase in both size and density of an infestation.
Seed in hay and grain also contributes to the spread of the plant to new sites.
Seedbank propagule persistence
A single hoary cress plant can produce 1,000 to 5,000 seeds with a capability of 80 per cent survival.
The seed viability of this weed rapidly declines with age, with seeds not able to germinate after three years.
Hoary cress prefers warm-temperate regions and grows in dry, unshaded situations on uncultivated, heavy, alkaline, fertile soils up to sub alpine levels.
It occurs as a weed of cereal and horticultural crops, pastures, roadsides and neglected sites in areas with an annual rainfall exceeding 400 mm.
This weed is extremely hardy and is highly tolerant of fire, waterlogging, drought and freezing conditions.
Hoary cress can be found growing widely throughout much of the cereal growing areas of NSW and Victoria, and also the vegetable growing areas in western Victoria.
The icons on the calendar below represent the times of year for flowering, seeding, germination, the dormancy period of Hoary cress and also the optimum time for treatment.
Agricultural and economic impacts
Stock losses from grazing hoary cress have occurred, but are rare.
Milk and meat can be tainted if the plant is eaten by stock, with the condition persisting for about a week after animals have been removed from the infested area.
The plant has serious impacts on crop yields and can interfere with harvesting in some areas.
The presence of this weed in cropping areas can greatly reduce land value.
Social value and health impacts
Dense infestations of hoary cress may reduce some recreational activities and slightly inhibit human access.
The weed contains no spines or burrs and is not known to be poisonous to humans.
Prescribed measures for the control of noxious weeds
- Application of a registered herbicide
- Physical removal
Other management techniques
Changes in land use practices and spread prevention may also support hoary cress management after implementing the prescribed measures above.
Downs, S. n.d., Cardaria draba, Whitetop, Montana War on Weeds information sheet, viewed 07/04/03.
Esser, L. 1994, Cardaria draba, United States Department of Agriculture Forest Service, Fire Effects Information System (FEIS). http://www.fs.fed.us/database/feis/plants/forb/cardra/all.html, viewed 07/04/03.
Jewett, D. 2003, Noxious weed found to harbour viruses, Northern Plains Agricultural Research Laboratory.
Parson, WT & Cuthbertson, EG. 1992, Noxious weeds of Australia, Inkata Press, Melbourne, Sydney.
Department of Primary Industries, Regionally Prohibited Weed Information Sheet - Hoary Cress, 2010.