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German wasp | Vespula germanica

German wasp

Vespula germanica

Coral bush | Ardisia crenata

Coral bush

Ardisia crenata

Purple loosestrife | Lythrum salicaria

Purple loosestrife

Lythrum salicaria

Pom pom weed | Campuloclinium macrocephalum

Pom pom weed

Campuloclinium macrocephalum

Canarybird bush | Crotalaria agatiflora

Canarybird bush

Crotalaria agatiflora

Peanut butter cassia | Senna didymobotrya

Peanut butter cassia

Senna didymobotrya

Rubber vine | Cryptostegia grandiflora

Rubber vine

Cryptostegia grandiflora

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Environmental Programmes

In order to tackle our country’s socio-economic challenges, the government adopted the Outcomes based approach to improve government performance and providing focus on service delivery. find out more

Management of the invasive cord grass, Spartina alterniflora, in the Groot Brak Estuary: challenges in a complex estuarine system

Management of the invasive cord grass, Spartina alterniflora, in the Groot Brak Estuary: challenges in a complex estuarine system         
Ernita van Wyk1, Virgil Jacobs1, Janine Adams2 and Taryn Riddin2
1Invasive Species Programme, South African National Biodiversity Institute, Kirstenbosch Research Centre, Claremont 7735, South Africa
2Department of Botany, Nelson Mandela Metropolitan University, PO Box 7700, Port Elizabeth 6031, South Africa

Spartina alterniflora is an invasive cord grass native to the Atlantic and Gulf Coasts of North America. The species is adapted to living in salt marshes and estuaries and was found growing in the Groot Brak estuary between Mossel Bay and George in 2004. Research shows that, if left unmanaged, the population in the Groot Brak estuary can spread at a rate 0.162 ha per year and that it can cover 41% of the total vlei area. Currently, the plant occupies 0.9 ha of the intertidal marsh. Experiences from other management attempts, particularly from Washington State, suggest that small populations of this species can be eradicated. An additional advantage for management of the species in the Groot Brak and beyond is that this population does not produce viable seed. Despite these points favouring possible success, management of the species in a seasonally open-closed estuary is challenging. Mechanical removal encourages spread of the plant and therefore herbicides must be used. The use of a glyphosate-based herbicide (Kilomax) was approved in 2010, but the application of the herbicide has been challenged by various factors: financial constraints and the transition of operational responsibility from one agency to another, administrative delays in putting contractors in-field and a  relatively short treatment season influenced by  whether the  estuary mouth is open or closed, such that when the mouth is closed, the plants are submerged for many months and inaccessible for treatment. Treatment must also be confined to low tides, low wind speeds and dry conditions, i.e. no rain. Various treatments are possible and are being tested within the constraints imposed by the estuarine system. These management options and a system to monitor the response of the Spartina population to the treatments are described.

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General News Updates

2019 National Symposium on Biological Invasio…

26-02-2019

This is your invitation to South Africa's 2019 National Symposium on Biological Invasions. The convention is hosted by the Centre for Invasion Biology (CIB), University of Stellenbosch, and the Biolo... Read more

2019 Invasive Species Training

22-01-2019

During the past five years (2014-2018), ISSA invasive species trainers have trained 4 000 in the identification of invasive species and laws pertaining to invasive species across South Africa.  ... Read more

Alien Grass Working Group

04-09-2018

Who are we? The South African National Alien Grass Working Group was jointly initiated by the South African Biodiversity Institute (SANBI) and the Centre for Excellence in Invasion Biology (C·I·B) in... Read more

Permits for planting indigenous Cynodon?

01-03-2018

On 16 February, 2018, South Africa's Department of Environmental Affairs issued amendments to the regulations and lists relating to the National List of Invasive Species.  Updates to the draft&n... Read more

Invasive species training 2018 dates released

28-02-2018

Interested in invasive species?  How much do you know about NEMBA invasive species compliance for landowners and organs of state? The South African Green Industries Council (SAGIC) have released... Read more

Communications post for Africa advertised

25-01-2018

The Nature Conservancy has advertised a brand new post:  Communications Manager, Africa Region. Knowledge of invasive species and water would be an asset in this post. See details below:    Job Titl... Read more