Biosecurity Queensland has placed movement restrictions on four out of the five properties in the Mackay area that originally reported red witchweed. This includes the initial affected property.
Biosecurity Queensland is now extending the surveillance area to check properties further out to see if the weed has spread.
Mature red witchweed (Striga asiatica) plant with roots parasitizing maize. Photo: D. L. Nickren
Surveillance further afield has been based on potential high risk pathways for the weed to spread, such as the movement of machinery.
To date, Biosecurity Queensland has not found any weed outside of these properties but this work is continuing.
Biosecurity Queensland will continue to work with the owners and industry to ensure there is some business continuity.
Properties placed under movement restrictions can not move equipment, soil or plant material on or off an affected property without approval from Biosecurity Queensland.
Advice for producers
Producers are urged to follow good biosecurity practices to reduce the potential spread of this weed including actions like appropriate wash down of equipment.
If producers suspect they have red witchweed they must report the weed immediately to Biosecurity Queensland on 13 25 23.
Producers must not attempt to remove any flowering plants, as this may allow the weed to spread tiny, dust-like seeds.
Seeds are primarily spread within the soil and can be moved over long distances. The weed has a complex underground root system which can be retained even if the flower is removed. Therefore, keep the weed in place until Biosecurity Queensland can investigate.
Do not spray the weed with herbicides without direction from Biosecurity Queensland as intact samples are required to identify red witchweed.
Producers should mark or clearly note the location of the weed, and where possible take photos that may be used to help with identification.
If red witchweed is suspected, soil, machinery or products that might contain soil should not be moved off-site until a Biosecurity Queensland officer has given approval.
Identifying red witchweed
- Grows 20-40 cm tall. Attached to roots of its host.
- Leaves are arranged in opposite pairs along the stem. Leaves are 6-40 mm long and 1-4 mm wide and have a tapered pointed tip.
- Flowers are 5-20 mm long.
- Seeds are very small and remain viable in the soil for up to 15 years.
More information
For more information on red witchweed, visit www.daff.qld.gov.au or call 13 25 23.
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