Experimental inoculations of the rust fungus Puccinia xanthii, a biological control agent against Noogoora burr (Xanthium occidentale) in northern Australia
Veronica EdgarA and Blair Grace, Northern Territory Department of Infrastructure, Planning and Environment, Palmerston, Northern Territory 0831, Australia and Cooperative Research Centre for Australian Weed Management.
A previously Northern Territory University.
Noogoora burr (Xanthium occidentale) is a large and growing problem in the Northern Territory and the north-west of Western Australia. A rust fungus (Puccinia xanthii) helps control the weed in parts of eastern Australia. This fungus is present in far northern Australia, but has little effect on the plant. It has been suggested that temperature and humidity requirements of the rust are not met in far northern Australia so a field trial was set up to test this theory.
We found that environmental conditions do limit the spread and effects of the rust in the Northern Territory. Humidity at night, when temperatures are lowest was an important factor in limiting rust epidemics. The rust spread quickly in humid conditions, but rust infection was only ever minor, and not enough to kill established plants. Strains of the rust that can tolerate higher temperatures, and possibly shorter periods with high humidity, may be required for successful control of X. occidentale in far northern Australia.
Keywords: Epidemics, microclimate.
Plant Protection Quarterly (2004) 19 (3) 98-101.