Investigating sustainable production of the Australian medicinal plant Centipeda cunninghamii (DC.) A. Braun & Asch. (Asteraceae)

Centipeda cunninghamii, commonly known as old man weed, is an endemic Australian traditional medicinal plant with over 150 years of documented use. Extracts of the plant have been patented for use in a range of applications. Recently, the phytochemistry and bioactivity have been elucidated, enabling high quality extracts to be produced. Although originally wild-harvested, a fledgling industry had developed, but many aspects of C. cunninghamii production had not been evaluated on a scientific and systematic basis. With a view to establishment of a sustainable Centipeda industry, a series of field and pot trials were conducted over three growing seasons in southern Victoria to evaluate accessions of C. cunninghamii for suitability for commercial cultivation, to investigate agronomic practices for maximising yield, to determine optimal harvest time and postharvest procedures, to maximise yield and levels of bioactive constituents, and to identify key pests and diseases. The study led to the identification of two superior phenotypes. A planting density of 10 m^-2 was optimal and yield of total dry matter, and thus bioactive constituents, was superior when two or more harvests were done during the flowering season. Liming the soil prior to planting was detrimental, as was adding potassium fertiliser. Deficit irrigation did not increase levels of bioactives. C. cunninghamii appears to be robust and to have a consistent phytochemical profile that is not affected by many basic agronomic practices. Few pests and diseases were observed, although both plant hoppers and chrysanthemum rust have potential to become more important in future cropping systems.