RBG Melbourne is home to 10,000 species and over 50,000 plants. Some of these plants could be at risk of being damaged, destroyed or becoming hosts for serious exotic pests. RBG Melbourne works closely with Crop Health Services and Plant Standards, Department of Primary Industries Victoria to carry out testing and inspections to ensure the early detection of any serious pests.
Wherever possible, Integrated Pest Management (IPM) principles are used in the Gardens to control pests. IPM relies on observation through regular monitoring to decide if pest control is actually needed. IPM is ‘integrated’ because it involves using a range of biological (predators), chemical, cultural/physical techniques to maintain pest populations under a level of acceptable damage (threshold). Past methods of pest control were often aimed at total eradication. It was found that accepting some minor damage to plants resulted in far less reliance on agricultural chemicals as the ‘all-in-one’ solution.
The Pest Triangle is a handy illustration how a pest outbreak can occur and how this might also be controlled. All three elements: Pest, Host, Environment need to be available for damage or disease to occur. We can influence the impact of a particular pest by giving attention to these elements in turn. Firstly, we can prevent the pest gaining entry to our garden by ensuring the plants and landscape materials such as soil and mulch are pest free. Secondly, we can improve the growing environment for our plants and reduce it favouring pests by actions such as improving drainage and air flow. Thirdly, we can grow plants that are not susceptible or are resistant to pests.
Biosecurity is improved through combining border quarantine and Integrated Pest Management (IPM) practices. Border quarantine needs to identify the pathways a significant pest may enter or leave the site. IPM seeks to manage existing pest problems both to reduce damage within the landscape and to reduce the risk of infested material leaving the site. Figure 2- Border Quarantine and Pest Triangle Schematic shows how pathways and improvements to pest management can be identified for the Royal Botanic Gardens Melbourne. Border Quarantine and Pest Triangle Schematic (MS Word - 28 kb)
Adapted from Agrios (1988). For more details on application of Pest Triangle and Integrated Pest Management Principles see Jan 2010 Pest Triangle and Integrated Pest Managment Principles (WORD - 36kb)
Phytophthora spp. (lit. ‘plant destroyer’) are fungi-like organisms that are world-renowned as one of the most serious threats to agriculture, gardens and natural habitats. Some of these diseases can also be a problem at RBG Melbourne. Frequent mulch applications, efficient irrigation are some of the non-chemical methods used to reduce significant outbreaks of Phytophthora spp.
Early and later images of symptoms of the disease Phytophthora cactorum attacking an Madrone Arbutus menziesii in the Gardens. It has girdled the trunk – effectively ring-barking the young tree. In the second image the disease has progressed up the trunk to over 1.2 metres from the ground. It is possible that the high levels of 2010 winter-spring rainfall provided the right conditions for this outbreak. There were no effective controls against the disease in this situation
Pest management RBG Cranbourne – introduced mammals
What introduced or pest animals are at RBG Cranbourne?
What impacts do pest animals have in the Gardens?
Foxes – and the Southern Brown Bandicoot
Predation by foxes has the potential to impact on the Southern Brown Bandicoot population at the Royal Botanic Gardens Cranbourne (RBG Cranbourne).
Southern Brown Bandicoots are an endangered species listed under the Federal Government’s Environment Protection and Biodiversity Conservation Act 1999 (EPBC). The natural distribution of the species extends from Sydney to Adelaide within about 50 km of the coastline. They were reportedly common and widespread when Europeans first settled in Australia. The species has declined dramatically in range and number since European settlement. Recovery Plans have been developed by Federal and State Governments to try and secure remaining populations. The species is threatened by habitat loss, isolation and predation by introduced predators such as foxes. There are now relatively few healthy, secure populations remaining on the Australian mainland.
RBG Cranbourne supports one of the few secure populations remaining in the Melbourne and Western Port region. RBG Cranbourne is regarded as one of the best sites for Southern Brown Bandicoots anywhere in Australia. We estimate that between 250 and 500 individuals occur on-site. At many other sites throughout south-eastern Australia they have declined or disappeared in recent decades. Their survival and common occurrence at RGB Cranbourne is because we protect and manage their habitat and actively control predators such as foxes.
Bandicoots are seen regularly by visitors to RBG Cranbourne and they occur right across the site. Most often seen around the picnic area or generally on walking tracks through the heathy vegetation, they also regularly forage around garden areas. Whilst they can be active throughout the day, the best time to see them is in the late afternoon or early evening when they emerge from nests to dig for soil invertebrates and underground fungi.
Bandicoots are solitary animals that breed seasonally throughout the spring. They produce litters of 2–3 young and may have up to 3 litters in rapid succession between September and January. The young stay in the mother’s pouch for several weeks before they emerge and quickly become independent, when they move away from their mother’s home range and try to find a suitable patch of habitat they can call home.
Cats found in RBG Cranbourne are most likely pets from surrounding areas, with some feral individuals. Cats are very efficient hunters and in addition to catching birds and mammals they are known to hunt numerous reptile, amphibian and invertebrate species. Increased housing density adjacent to the Gardens is likely to increase the numbers of domestic pets in the area, thereby increasing predation rates on native fauna.
Rabbits have a number of negative effects on the native vegetation. Their grazing inhibits the regeneration of native vegetation and eventually may result in the local extinction of some of the smaller plants. Their grazing may also lead to changes in the structure of the vegetation, thinning out the understorey and so reducing the amount of ground cover for small ground-dwelling native species, thereby exposing them to increased rates of predation.
What strategies are used to control pest animals?
- Predator-proof fence - A predator-proof fence has been erected around the site at RBG Cranbourne.
- Baiting - An active fox-baiting program is in effect across the whole of the RBG Cranbourne site and a number of bait stations have been set up in the immediate surrounds of the Gardens.
- Monitoring - The site is constantly monitored for pest animals. Through monitoring we are able to recognise when there are increases in activity and target our control programs accordingly.
Why aren’t pet dogs allowed at RBG Cranbourne?
Dogs and other domestic pets are not permitted within RBG Cranbourne, including the Australian Garden and car-parking areas.
RBG Cranbourne is an isolated fragment of remnant vegetation and is classified as an area of State significance for the conservation of biodiversity. As well as providing a rare glimpse of the type of vegetation which once covered much of the Western Port and Port Phillip Bay regions, it provides habitat for a number of ‘endangered’, ‘vulnerable’ and ‘at risk’ native animals.
Native animals are extremely sensitive to the sound of barking and the lasting scents of dogs and other animals. Native animals are also vulnerable to the diseases, pathogens and parasites that dogs can unwittingly bring into the Gardens. Smaller animals can be killed and larger animals disturbed and frightened by dogs and cats.
While the Royal Botanic Gardens recognises that pets can be important members of our families, we need to balance this against the needs of the native flora and fauna on-site.
Last updated 30 Nov 2011