Restricted invasive plant Rubber vine Cryptostegia grandiflora and Cryptostegia madagascariensis Rubber vine’s ability to quickly spread and colonise This decreases biodiversity and prevents access to both areas makes it a threat to many areas of northern stock and native animals. It also creates habitat for feral Australia. Due to this ability, rubber vine is listed as a animals. Infestations expand outward from waterways, Weed of National Significance. hillsides and pastures, resulting in loss of grazing land and increased difficulty in mustering stock. Rubber vine generally invades waterways first, where the seeds germinate in moist silt layers after rain. The plant Rubber vine is poisonous to stock, though seldom eaten. smothers riparian vegetation and forms dense, sometimes Most deaths due to rubber vine occur after stock have impenetrable, thickets. been stressed, or when other feed is scarce. Legal requirements Methods of spread Rubber vine (Cryptostegia grandiflora) and ornamental Rubber vine seeds spread by wind and water. rubber vine (Cryptostegia madagascariensis) are category 3 restricted invasive plants under the Biosecurity Act Habitat and distribution 2014. They must not be given away, sold, or released into the environment. The Act requires everyone to take Rubber vine is native to Madagascar, but is now widely all reasonable and practical measures to minimise the distributed throughout tropical and subtropical regions of biosecurity risks associated with invasive plants under the world. their control. This is called a general biosecurity obligation (GBO). This fact sheet gives examples of how you can meet The plant was introduced to Australia as an ornamental your GBO. shrub in 1875 or earlier, and was popular in north Queensland mining settlements due to its luxuriant growth At a local level, each local government must have a even under harsh conditions. Weedy infestations were biosecurity plan that covers invasive plants in its area. recorded around Charters Towers early this century. This plan may include actions to be taken on certain species. Some of these actions may be required under Rubber vine prefers areas where annual rainfall local laws. Contact your local government for more is 400–1400 mm, and is well adapted to a monsoonal information. climate. Infestations of rubber vine are now found throughout Description river systems of southern Cape York and the Gulf of Carpentaria, south along the coast to the Burnett River, Rubber vine is a vigorous climber with twining, whip-like and isolated infestations occur as far south as Gatton and shoots that can grow unsupported as an untidy, multi- as far west as the Northern Territory border. stemmed shrub 1–2 m high, or it can scramble up to 30 m high in trees. The stems, leaves and unripe pods exude a Infestations are common throughout central Queensland, white, milky sap when broken or cut. while in western Queensland there are infestations in the Mount Isa, Longreach and Aramac areas. Isolated Leaves are dark green and somewhat glossy, 6−10 cm infestations have been reported in Western Australia. long, 3−5 cm wide, and in opposite pairs. Flowers are large and showy, with five white to light purple petals arranged in a funnel shape. Control The seed pods are rigid and grow in pairs at the end of a Managing rubber vine short stalk. The pods are 10–12 cm long, 3–4 cm wide and The GBO requires a person to take reasonable and each can contain up to 450 brown seeds. Each seed has a practical measures to minimise the biosecurity risks tuft of long, white, silky hairs, which enable easy dispersal posed by rubber vine. This fact sheet provides information by wind and water. and some options for controlling rubber vine. Ornamental rubber vine (Cryptostegia madagascariensis) Effective control of rubber vine can be achieved by a is a shrub up to 3 m tall, if unsupported and stems can number of methods, alone or in combination depending climb to 10 m if supported. Bark is sparsely dotted with on the situation and the severity of infestation. All areas corky patches. Leaves are dark green, glossy, with pale treated must be periodically checked and any regrowth underside, 2–11 cm long, 1.5–5.5 cm wide, arranged treated or the initial treatment efforts will be wasted. in opposite pairs. Plant produces milky latex sap when leaves, fruit or branches are cut. Rubber vine seed is most commonly spread by wind and running water. Flowers are pink-purple, 4–6 cm long, found near branchlet ends. Pods are 7–9 cm long, contain seeds It is thus difficult to prevent seed coming onto uninfested 5–5.9 mm long, 1.8–3.5 mm wide, topped with silky tuft land if there is rubber vine anywhere in the area. Your of white hairs. goal should be to prevent rubber vine from establishing and forming dense infestations. It is essential to regularly Life cycle inspect all areas of your property, paying particular attention to creeks and gullies. Rubber vine flowers at any time of year if sufficient moisture is available. Usually, June and July are the only This is most important where prevailing winds are known non-flowering months. Plant stem diameter must be to blow from infested areas, or where infestations approximately 20 mm before flowering can occur. occur upstream. Seed pod formation occurs from spring to late autumn, with Any isolated plants located should be treated promptly. peak seed production corresponding to maximum flowering. All control of rubber vine will require follow-up treatments Eventually, pods dry out and split open, with pod-splitting to keep your property clean. As rubber vine spreads occurring approximately 200 days after formation. quickly, small infestations should be controlled first to Seeds are scattered by wind, but also carried downstream prevent them from becoming major problem areas. Dense by water. Approximately 95% of seed is viable, although infestations are difficult and costly to treat. germination requires favourable temperature and soil moisture conditions. 2 Rubber vine Cryptostegia grandiflora and Cryptostegia madagascariensis Follow-up treatment must be budgeted for within Insects the overall control program. Techniques need to be Also established is the moth Euclasta whalleyi, whose integrated for successful rubber vine management. larvae are leaf feeders. Observation indicates the moth Consideration should be given to coordinating control over prefers stressed plants, either from limited soil moisture a catchment area. or high levels of rust infection. Five suggested strategies for controlling rubber vine in The moth’s period of activity is the dry season. A native scattered, medium, and dense infestations are outlined fly parasite and a disease can reduce the localised in Table 2. abundance of the Euclasta larvae. Fire The larvae are tapered at both ends, grow up to 30 mm Rubber vine infestations can be very effectively controlled long, and are grey-brown with orange dots along their by burning. Preparing and managing fuel load prior to sides. Fine silken threads and black, bead-like droppings burning, and following up in a timely manner after the are often found near the larval feeding damage. fires, are critical to the overall success of the program. The creamy-brown moths are active at night and rest at a 0 It is recommended that you perform two successive annual 45 angle from a surface, with their wings folded. The life burns. The first fire will open up the infestation to increase cycle from egg to adult takes 21–28 days. grass growth (fuel load) while killing rubber vine plants. Defoliation reduces the smothering effect on other The second fire will clean up the regrowth that occurs after vegetation and causes an increase in leaf litter and the first fire. promotes increased grass growth amongst rubber vine, An appropriate fire regime is an effective tool for managing increasing fuel loads required for fire management. rubber vine over the long term, as well as being an Decreased flower and pod production should reduce the effective follow-up to other control methods. ability of rubber vine to spread. Mechanical control Biological control is also important because it impacts on other control methods. Several mechanical techniques are effective in controlling rubber vine. The type of infestation will determine the Herbicide control technique required. Herbicides recommended for use on rubber vine are listed • Scattered or medium-density infestations: Where in Table 1 (overleaf). Preference ratings (taking account of possible, repeated slashing close to ground level effectiveness and cost) are shown. is recommended. Aerial application • Dense infestations: During winter, stick-raking or blade-ploughing reduces the bulk of the infestation. Three herbicides are currently registered for aerial Pasture should be sown and windrows burned to kill application (refer to Table 1. Two of these are foliar residual seed. Follow-up treatment is essential. It is herbicides and the other is a soil-applied herbicide. As important to comply with the relevant state and/or a result, the necessary conditions that apply to foliar local government native vegetation legislation, and it and soil applications is also applicable to the respective should be noted that causing even accidental death of chemical when aerially applied. vegetation can be a breach of this legislation. People considering aerial application are advised to contact 13 25 23 for current advice on use of this technique. Biological control Two biological control agents are successfully established, Foliar spray and their impact depends on abundance. Both agents The following points should be followed carefully: cause abnormal defoliation, creating an ‘energy sink’, which appears to reduce seed production. These agents • There must be little to no rust present as it affects the usually do not kill established rubber vine plants. health of the plant and its ability to take chemical up through its leaves.