Early Dectection Rapid Response: What we have achieved

Below are listed the projects associated with invasive plants that the EDDR programme is involved in:

Cylindropuntia tunicata (Lehm.) F. M. Knuth, (thistle chollas)

The emerging invasion of thistle chollas was brought to the attention of the team by Lesley Henderson of the Agricultural Research Council and co-ordinator of the South African Plant Invader Atlas. A stakeholder meeting was arranged and within weeks the populations of this invasive cactus in municipal areas surrounding the Camdeboo National Park outside Graaff-Reinet were chemically treated.

The speed of this action and additional awareness-raising through a farmers' meeting and distribution of a pamphlet alerted various land owners to the problem. These stakeholders have informed the team of previously unknown populations in Jansenville, Arbedeen, Darlington and areas to be incorporated into Addo National Park. This species could, given the highly dangerous nature of its thorns, have worse impacts than the once dense infestations of Opuntia ficus-indica, the prickly pear that used to cover much of the farm-land in the Eastern Cape.

A management plan to curb further spread of the primary plant populations was developed. A three stage management approach was adopted which entails the destruction of the primary plant populations using herbicides, an awareness raising campaign targeting members of the general public and lastly, organising a survey and monitoring programme to locate new infestations. Monitoring the overall effectiveness of the management strategy will also be initiated.

Melaleuca (paperbarks)

Cape Nature staff at Waterval Nature Reserve near Tulbagh recently noticed the emergence of 2 species of Melaleuca, M. ericifolia and M. quinquenervia on the Nature Reserve. Both species (from the family Myrtaceae) originate from Australia and are known as "paperbarks" due to their distinctly papery bark. These plants like to grow in seasonally inundated wetlands and so pose a threat to water resources and water-dependent biodiversity and related ecosystem services.

Melaleuca quinquenervia is a highly problematic invasive pest in Florida in the US, current annual expenditure on management is up to US$2.2 million. The Melaleuca populations at Waterval Nature Reserve are currently being controlled (cut and poisoned) and monitored with the ultimate aim of eradicating them completely. From preliminary observations, it seems that the oldest plants are about 10 years old, suggesting that the plants at Waterval had escaped notice until they grew large enough to be clearly distinguishable from the surrounding fynbos.

The Early Detection and Rapid Response (EDRR) Programme within SANBI co-ordinates this project while all related activities take place in collaboration with CapeNature, UCT, CIB (US), Working for Water and MTO (Forestry).

Lythrum salicaria (purple loosestrife)

Purple loosestrife is an aggressive, competitive wetland perennial from Eurasia that has invaded vast areas of the northern US and Canada, forming dense stands. The plant produces beautiful spikes of purple flowers (and an abundance of seeds) in summer and is most visible at this time.

The appearance of purple loosestrife on the Liesbeek River in the Western Cape was noticed by Liz Wheeler of Friends of the Liesbeek, about 2 years ago. The Friends have tried to control the plant since, but it is proving difficult to remove as it grows amongst other riparian plants and is well rooted. The EDRR Programme, together with Friends of the Liesbeek and the City of Cape Town and SANParks, are currently developing an intensive control plan (focusing on physical removal) for Lythrum sp. on the Liesbeek River, as the population may be small and localized enough to attempt complete eradication.

It is estimated that controlling this plant across 19 American states would cost about US$ 45 million per year (2002 estimate). Lythrum salicaria and Melaleuca quinquenervia have been designated as 2 of the top 100 worst invasive species globally (ISSG, 2000).

Ant Tree (Triplaris americana)

This species is a declared weed and potential transformer, according to the South African Plant Invader Atlas database. In addition, its leaves are poisonous. However, with its huge leaves and beautiful pink flowers, one can easily understand the rationale behind its recreational uses (it has been seen in private gardens, and even outside shopping malls in KwaZulu-Natal (KZN).This species invasive tendency was recently brought to the attention of the KZN team, by Geoff Nichols. The team has visited the site in question, collected specimens for the KZN Herbarium, and recorded the plant locations. The KZN team is currently looking out for more localities in the province, where T. americana is showing an invasive potential.

Pompom weed (Campuloclinium macrocephalum)

The EDRR team in Pretoria identified pompom weed (Campuloclinium macrocephalum) as one of the top priority species in the northern region (Gauteng, Free State, Limpopo, North West, Mpumalanga). Pompom weed originates from South America. It is not certain how the plant was introduced to South Africa, but it is suspected that the plant was brought in as an ornamental plant in the early 1970s. The plant initially established itself in disturbed sites such as roadsides, but has the potential to invade natural grasslands and wetlands and to displace good pasture vegetation.

Pompom is a declared category 1a weed outside of Guateng and must be controlled. Although established in Gauteng, pompom weed is considered emerging in the neighboring provinces (Limpopo, Mpumalanga, KZN, Free State, North West, and KwaZulu-Natal).

Efforts to control pompom weed in Free State, North West, Mpumalanga and Limpopo started in early 2009 by the EDRR Programme of SANBI in collaboration with the Working for Water Programme of the Department of Water and Environmental Affairs.

Hydrilla (Hydrilla verticillata)

Invasion of Hydrilla verticillata in South Africa was first noted at Pongolapoort Dam in KZN in 2006. H. verticillata is an aquatic weed, mainly invading dams and other aquatic systems. It is believed that H. verticillata invasion has been facilitated by the aquarium trade in most countries, while the fishing industry is also playing a major role in its invasion in South Africa.

H. verticillata originates from Asia. It is aggressive and has a high potential of invading other water bodies in the country. It belongs to Hydrocharitaceae family, which often exhibit characters of invasiveness. It has four ways of reproduction namely: seed, fragmentation, tubers and turions which gives it a competitive advantage over other aquatic plants, hence it is an aggressive invader and a habitat transformer.

The EDRR Programme has introduced long term monitoring of hydrilla invasion at Pongolapoort Dam. This involves integration of other stakeholders such as Working for Water (WfW) and ARC-PPRI. EDRR is taking a lead in conducting surveys, while the ARC is looking at biological control, and WfW is responsible for the containment and prevention of hydrilla spreading. The aim of conducting the surveys is to determine species composition; growth conditions, species abundance and verify areas invaded by Hydrilla.