Patterson's Curse (Echium plantagineum) is an invasive annual plant native to the area surrounding the Mediterranean Sea. It is also known as Paterson's Curse (with one "t"), Salvation Jane, Blueweed, Lady Campbell Weed, and Riverina Bluebell.
It was introduced to Australia in the 1880s, probably both as an accidental contaminate of pasture seed and as an ornamental plant. It is said that the name derives from the bitter experience of the Patterson family, early settlers of the country near Albury. They had seeds brought from Europe to beautify their garden, and then could only watch helplessly as the weed infested previously productive pastures for many miles around.
Patterson's Curse in flower. Patterson's Curse infesting the Warrumbungle National Park in New South Wales. In general, Patterson's Curse does not pose a significant problem in healthy, undisturbed habitat: this area has been degraded by overgrazing or rabbits.
Patterson's Curse is now the dominant pasture weed through much of New South Wales, Victoria, South Australia, and Tasmania and also infests native grasslands, heathlands and woodlands. The annual cost in control measures and lost production is estimated to be over $30 million.
Patterson's Curse has hairy, dark green, broadly oval rosette leaves to 30cm long; the several seeding stems grow to 120cm in height and develop branches with age. Flowers develop in clusters; they are purple, tubular, and 2-3 cm long with 5 petals. It has a fleshy taproot with smaller laterals.
Although generally a spring-flowering annual, Patterson's Curse is highly adaptable and given suitable rainfall some plants germinate out-of-season and endure for longer than one year. It is a very prolific seed producer; heavy infestations can yield up to 30,000 seeds per square metre.
Seed disperses on animal fur, through the alimentary tracts of birds and grazing animals, via water, and in particular as a hay or grain contaminant. Patterson's Curse can germinate under a wide variety of temperature conditions, tolerates dry periods well, and responds vigorously to fertiliser. The plants contain alkaloids and, when eaten in large quantities, cause reduced livestock weight or even (in severe cases) death.
Patterson's Curse can rapidly establish a large population on disturbed ground and competes vigorously with both smaller plants and the seedlings of regenerating overstorey species. Its spread has been greatly aided by human-induced habitat degradation, particularly the removal of perennial grasses through overgrazing by sheep and cattle and the introduction of the rabbit. Patterson's Curse is rarely able to establish itself in habitats where the native vegetation is healthy and undisturbed.
Control is carried out by hand (for small infestations) or with any of a variety of herbicides, and must be continued over many years to reduce the seedbank. (Most seeds germinate in the first year, but some survive for as long as five years before germinating.) In the longer term, perennial grasses (which do not need to regenerate from seed each year) can out-compete Patterson's Curse, and any increase in perennial cover produces a direct decrease in Patterson's Curse.
The CSIRO has investigated numerous biological control measures, and of the 100-odd insects found feeding on Patterson's Curse in the Mediteranian, judged six safe to release in Australia without endangering crops or native plants. The New South Wales Department of Agriculture has released the weevils Mogulones larvatus and Mogulones geographicus and the flea beetle Longitarsus echii. While the CSIRO is modestly optimistic, it is expected that biological control measures, if they are successful at all, will take decades to be effective.
Three other Echium species have been introduced and are of concern; Viper's Bugloss (Eichium vulgare) is the most common of them. Viper's Bugloss is biennial, with a single unbranched flowering stem and smaller, more blue flowers, but is otherwise similar.