Pest plant - Hoary cress
- Fact sheet
- August 2015
Hoary cress (Cardaria draba) is a perennial weed easily spread across paddocks by cultivation.
Description
- erect perennial weed to 75cm
- leaves and stems are blue-green with fine white hairs
- first leaves form a rosette at ground level, are wedge shaped and up to 10cm
- erect stem develops later and has smaller, oval leaves
- flowers are white in colour with 4 petals, 4-6mm wide, arranged in dense groups on fine stalks at the top of the stem
- fruit is a 2-4mm heart-shaped capsule, with 1-2 reddish brown seeds, 2mm long
- taproot can be 2 metres deep, with many horizontal branching roots.
Why is it a problem?
- reduces the yield of cereal and interferes with harvesting
- if eaten by stock, it taints meat and milk and may be poisonous in larger quantities.
Distribution
- Eyre Peninsula – isolated infestations on lower and eastern EP
- Northern pastoral – sparse in marginal country, not present elsewhere
- Northern agricultural districts and Yorke Peninsula – scattered infestations
- Murray Mallee – isolated outbreaks
- South East – isolated outbreaks
- Central region – very isolated patches.
Ecology
- deep-rooted perennial that reproduces by suckering from rootstocks or by seed
- seeds germinate in autumn, new growth occurs from the crown and root buds in autumn, stems grow over winter
- plant flowers September-November.
How it spreads
- a single plant can produce 1000-5000 seeds with 80% viability
- main method of dispersal is root fragments moved by cultivation.