Delairea odorata (Cape ivy)

Control of D. odorata with fire or grazing animals has not been reported, although using goats might be feasible. However, D. odorata contains pyrrolizidine alkaloids, which are known to be potent mammalian hepato-toxins.

Although very labour intensive, hand-pulling of D. odorata is usually the preferred control method. To prevent new infestations in other areas, the plant material that has been removed must be disposed of carefully.

Clopyralid has been used successfully in Australia (Fagg, 1989). In California, glyphosate alone provided only very temporary control (Bossard and Benefield, 1995), but when a mixture of glyphosate + triclopyr + silicone surfactant in water was used, it provided successful control after two applications (Bossard, 2000). Damage to non-target vegetation is likely, and care should be taken to minimize this.

There are no approved biological control agents available to manage D. odorata. However, in the United States, a project to develop such agents was launched by USDA-ARS in 1998 (Balciunas and Archbald, 1999). Surveys were conducted in South Africa for natural enemies of this vine and during two years research, several hundred insects attacking D. odorata were identified (Grobbelaar et al., 2003). Two of these insect species, the Cape ivy gall fly (Parafreutreta regalis Munro) and the Cape ivy stem moth (Digitivalva delaireae Gaedike & Kruger) are currently being evaluated at the USDA-ARS quarantine facility in Albany, California and at a facility in Pretoria, South Africa to determine if they are safe enough to release in North America (Balciunas, 2001a).

Whatever control method is used, careful monitoring and removal of any resprouts and seedlings is essential, or within a matter of months the treated area will become indistinguishable from adjacent untreated areas.