Paterson’s Curse – pretty but a problem

Posted on 24 October, 2016 by Connecting Country

The flower of Patterson's Curse close up!

The flower of Paterson’s curse close up!

While out in the field Connecting Country staff, Bonnie Humphreys and Jarrod Coote, have noticed a number of out-breaks of Paterson’s Curse in our region. This weed is easily recognisable at the moment by the swathes of purple flowers. Yes it’s pretty, but it’s also a potentially big problem.

Paterson’s curse is a winter annual herb that often becomes the dominant species in pastures. It is a prolific seeder that can produce more than 5000 seeds per plant per year. Large quantities of seeds may accumulate in the soil over several years. For example, a seed bank of up to 30 000 seeds per square metre has been reported. Seeds may remain dormant in the soil for up to five years.

Paterson’s curse is considered a weed because:

It reduces pasture productivity and is toxic to livestock.
It can degrade the natural environment, compromising habitat values by crowding out and suppressing native vegetation.
Hay and grain infested with it fetch lower prices.
It affects human health. Some people are allergic to the pollen and the rough hairy texture of the leaves and stems causes skin irritation in people having close contact with the plant.

The life cycle of Paterson’s curse is important to understand in managing infestations. Currently plants are flowering and set seed from the top of the stem down. The plant then dies back and seeds germinate in the residual bare ground. As the plant grows it forms a rosette and then sends up the flowering stem.

So right now, the best thing to do is to map infestations and chip or spray emerging rosettes in Autumn next year. Rosettes can be easily chipped out and turned upside down to dry in the sun or sprayed with a registered herbicide.