Cape ivy (German Ivy)

Delairea odorata (synonym Senecio mikanioides)

Background

Identification

• Climbing vine with small inconspicuous yellow flowers (see photo).
• Leaves and stems are smooth, shiny, hairless, plentiful, bright green. Leaves are 1 to 4 in. long, evenly spaced on stem, with 5 to 9 lobes each.
• Easily confused with native wild cucumber Marah fabaceus. Marah leaves are not as shiny, Marah stems are ribbed (not smooth), Marah produces many spiraling tendrils and Marah produces distinctive round 1 in. fruit covered in spines.

Identification key in: Hickman, J. ed. 1993. The Jepson Manual: Higher Plants of California. University of California Press.

Growth and spread

• Sends out runners which root and create new plants.
• Can resprout from fragments of runners or roots.

Habitat

• Native to South Africa.
• Grows well in shady and damp places, disturbed ground.

Impacts

• Highly invasive, spreads quickly, capable of blanketing native vegetation including trees (see photo).

Prevention and Control

Prevention

• Plant natives or spread native seed in disturbed areas.

General control notes

• Follow-up monitoring and treatment required to remove resprouts (Bossard 2000).

Manual or mechanical control

(Bossard 2000)

• Manual removal—use of pointed or pronged rake to remove stems and roots; plant material should be removed from site; should not be ground or dumped unbagged due to sprouting of plant fragments; supplemental vegetation should be considered to prevent erosion and invasion by other invasive plants; potential disturbance to non-target plant species since tends to grow in mats close to ground.,
• Prescribed burning—not extensively studied since foliage has high moisture content.

Biological control

• Biological control agents—currently none are available for release in California (Bossard 2000). However, the US Department of Agriculture, Agricultural Research Service (USDA-ARS) is conducting host specificity tests on the Cape ivy gall fly (Parafreutreta regalis) and stem-boring moth (Digitivalva delaireae) (Balciunas 2003).

Chemical control

• Application of herbicides—mixture of 0.5% glyphosate, 0.5% triclopyr, and 0.1% silicone surfactant applied as a foliar spray proved effective in removal project in San Francisco; optimal time to apply is in late spring past flowering stage (Bossard and Benefield 1995); use cautiously along pond and stream banks and where water table is close to the surface (Bossard 2000).
• Estimated costs: costs for materials and application by a contractor are approximately $250 per acre for glyphosate, depending on size of treatment area, scale of treatment, and dosage. It is recommended to contract a licensed professional for herbicide applications (Gibbons et al. 1999).

References and more information