By simulating summer growth conditions, Queensland University scientists have shown parthenium will grow as well — albeit more slowly — in Armidale and Ballarat as in Queensland.
Research team leader, Dr Steve Adkins, says Malaysia's concerns over parthenium seed contamination of wheat shipments are a good indication of the problems the weed could cause for the Australian grains industry.
In the wake of these concerns, the permitted level of parthenium seeds in wheat has been reduced from 25 to eight seeds per 500 millilitres in Queensland. In the rest of Australia it is zero.
The research team's three-year brief, with support from growers through the GRDC, was to research the biology and ecology of parthenium — about which relatively little was known in Australia.
The team found:
- parthenium was a prodigious producer (up to 340 million/ha) of long-lived seed
- indications that burial by flooding, cultivation or animal activity might help the seed persist, and
- in glasshouse trials, parthenium seed germinated significantly faster than its grass competitors, perhaps explaining why it was so aggressive and able to out-compete other species.