Determining best control methods for the National Environmental Alert List species, Retama raetam (Forssk.) Webb (white weeping broom) in Western Australia
K.A. Bettink and K.L. Brown, Department of Environment and Conservation, PO Box 1167, Bentley Delivery Centre, Western Australia 6983, Australia.
Field experiments were conducted in Perth, Western Australia between 2006 and 2007 to assess the efficacy of various methods in controlling the National Environmental Alert List species Retama raetam (Forssk.) Webb (white weeping broom). Native to the Mediterranean region, this species is naturalized in Western Australia in relatively low numbers and mainly restricted to disturbed sites on the western edge of the Swan Coastal Plain. Hand removal and herbicide treatment are known effective methods of controlling seedlings, however a preferred method of treating mature plants has not yet been developed.
This study tested a range of physical and chemical treatments, with results indicating that two treatments were highly effective on mature plants. Both the cut and paint method with 50% glyphosate and basal bark with triclopyr at 1.25 L 60 L-1 resulted in 100% mortality 12 months after application. Basal bark with tricoplyr and picloram (1.25 L 60 L-1) was less effective than triclopyr on its own, achieving only 70% mortality. Less effective again was the felling method, resulting in mortality in 50% of plants, the remaining 50% vigorously resprouting within five months. Foliar spraying with triclopyr (17 mL 10 L-1) and stem injection with 50% glyphosate were less effective again, resulting in 40% and 50% mortality respectively 12 months after treatment.
Plant Protection Quarterly (2011) 26 (1) 36-38.