Graeme Jennings reports on a program that is fighting the advance of a potentially devastating weed
[Photo: Aerial attack: a helicopter applies a herbicide made from extracts of natural pine oil, which is used as a soil drench to kill the seeds of branched broomrape.]
Efforts to contain and eradicate from Australia the devastating parasitic weed "branched broomrape" are on track and should continue, according to the findings of a review of the eradication program. The review was lead by Emeritus Professor John Lovett, the former managing director of GRDC.
Infestations of branched broomrape are currently confined to SA but the weed has national implications because it poses a threat to Australian exports, with many of the nation"s export partners refusing to buy produce that might contain branched broomrape seed. These include South Korea, Indonesia, Malaysia, Iran, New Zealand and the US.
While the parasite is currently confined to SA"s Murray Mallee, its potential range extends across southern Australia, as far north as Central Queensland and Geraldton in WA. This, combined with the trade implications, means the eradication project is supported by the state and Australian governments, and industry, through the GRDC.
Professor Lovett says the potentially wide distribution of branched broomrape plus its wide host range make it imperative that branched broomrape be effectively managed and ultimately eradicated. Atrisk crops include oilseeds, faba beans, lupins, vetch, pasture legumes and a variety of annual horticultural crops.
Despite the fact broomrape does not attack cereals, it is still an issue for cereal growers and marketers because it readily attaches to many of the common broadleafed weeds found in cereal crops, making effective broadleafed weed control a vital part of the eradication program. The review recommends that eradication of the parasite remains the principal objective of the program and that it be extended for three years from 1 July next year.
Phil Warren, leader of the branched broomrape eradication team, says broomrape seed remains viable in the soil for more than a decade, so 12 years without emergence is required before the restrictions imposed under quarantine provisions can be lifted. Consequently, it is believed the program needs to continue well beyond 2009 and be supported with adequate resources if the weed is to be eradicated.
Weeds scientist Dr Dane Panetta, who has developed an assessment tool for weed eradication programs, says the branched broomrape eradication program scored 38 per cent, a jump of 6.4 per cent on the previous year. Dr Panetta, a principal scientist with the Queensland Department of Natural Resources and Mines and the Cooperative Research Centre for Australian Weed Management (Weeds CRC), says this puts the broomrape initiative on a steep upward trend.
The eradication score takes into account the effectiveness of detection, whether the area infested is increasing or decreasing, the number of new infestations and their location, and the number of infestations where plants have not been found for 12 months or more.
The final outcome of any eradication effort is determined by"an inter-play of biological, economic and social factors," Dr Panetta says."However, without mechanisms in place to ensure long-term continuity of funding and staffing the risk of failure will be high. The resources available to pursue any eradication objective are critical and often need to be maintained over many years for success to be achieved."
Area of infestation is another critical factor. With broomrape on 6204 hectares spread across more than 190,000ha, eradicating the weed is a huge challenge.
GRDC Research Code UA00071
For more information: Phil Warren, 08 8303 9687, firstname.lastname@example.org;
John Lovett, 02 6227 5050, email@example.com;
Dr Dane Panetta, 07 3375 0735, firstname.lastname@example.org