Invasive Water Lilies.

Invasive yellow water lilies (Nymphaea mexicana and hybrids) have invaded rivers, lakes and dams in South Africa. Dense infestations can increase siltation, block waterways and hamper recreational activities. Thick mats provide breeding grounds for mosquitoes and disrupt the aquatic environment by reducing light penetration. Rotting material increases nutrients and reduces oxygen in the water which can be fatal to fish. The degradation of water bodies reduces the biodiversity of the ecosystem. For more information and detailed descriptions download: http://invasives.org.za/component/k2/item/693-yellow-water-lily-nymphaea-mexicana http://www.arc.agric.za/arc-ppri/Newsletter%20Library/SAPIA%20News%20No.%2049,%20July%202018.pdf     Share this:Click to email this to a friend (Opens in new window)Click to print (Opens in new window)Click to share on Facebook (Opens in new window)Click to share on Twitter (Opens in new window)Click to share on Reddit (Opens in new...

Read More

Cat’s claw creeper (Dolichandra unguis-cati) (Bignoneaceae)

Cat’s claw creeper (Dolichandra unguis-cati)  (Bignoneaceae)

English: Cat’s Claw Creeper.  Afrikaans: Katteklouranker The weed The exotic vine Dolichandra unguis-cati (formerly Macfadyena unguis-cati) is a woody, evergreen creeper that has become a significant threat to biodiversity in many sensitive ecosystems around South Africa. The vine is originally native to central, and tropical South America, including the West Indies, but has become invasive in a number of regions of Southern Africa, Australia, New Zealand, India, Mauritius, China, New Caledonia and the USA, including Hawaii. This extensive range has been facilitated through the horticultural trade which distributed the plant as an ornamental. Showy yellow flowers coupled with its climbing habit made the fast-growing creeper ideal as a hedging plant or natural screen for unsightly walls and buildings. The plants’ ability to ‘climb’ is facilitated by its distinctive leaves which consist of two leaflets and a modified three-forked tendril. Each tendril is tipped with a tiny hardened hook which can attach to most surfaces enabling the vine to grow up walls, tree trunks and over other vegetation. It is these tendrils that resemble claws and the feature from which the plant draws its name. Within South Africa, although spreading, cat’s claw creeper is considered to be in the early stages of invasion due to its relatively small distribution. Nevertheless, the weed has formed some very dense infestations in Gauteng, Kwazulu-Natal, Limpopo, Mpumalanga and the North West. Within these provinces the weed has become a significant invader of cultivated orchards and plantations, riparian corridors, natural forest remnants and disturbed areas such as roadsides and urban spaces. Vigorous growth allows the vine to sprawl over other vegetation and, through a combination of both shading and weight, it can kill even the largest canopy trees. In the absence of climbing support, individual stems grow along the ground resulting in a thick carpet which precludes the growth and seed germination of indigenous understorey vegetation. ? ? ? ?Cat’s claw creeper infestation  ?Leaves with ‘claws’ ?Hedge in bloom   Control Due to the problems associated with cat’s claw creeper infestations, D. unguis-cati has been declared a category 1b weed in South Africa in terms of the Alien and Invasive Species Regulations (AIS), National Environmental Management: Biodiversity Act (Act No 10 of 2004), which necessitates its control or eradication where possible. No trade or planting is allowed.? The management of cat’s claw creeper is, however, extremely difficult and little has been achieved with either mechanical or chemical control. Control is hampered by the weed’s extensive vegetative growth, profuse seed production, and the presence of subterranean root tubers. Individual stems growing along the ground readily develop roots and tubers wherever nodes touch the ground and can develop into new plants if separated from the parent plant. The presence of tubers therefore, makes infestations extremely...

Read More

How South Africa is keeping its worst invader – famine weed – at bay

How South Africa is keeping its worst invader – famine weed – at bay

Author Blair Cowie PhD Candidate Invasive Species Management, University of the Witwatersrand Disclosure statement Blair Cowie received funding from the University of the Witwatersrand, the Centre of Excellence for Invasion Biology (CIB) & the Agricultural Research Council -Plant Protection Research Institute (ARC-PPRI). Partners University of the Witwatersrand provides support as a hosting partner of The Conversation AFRICA. The Conversation is funded by Barclays Africa and eight universities, including the Cape Peninsula University of Technology, Rhodes University, Stellenbosch University and the Universities of Cape Town, Johannesburg, Kwa-Zulu Natal, Pretoria, and South Africa. It is hosted by the Universities of the Witwatersrand and Western Cape, the African Population and Health Research Centre and the Nigerian Academy of Science. The Bill & Melinda Gates Foundation is a Strategic Partner. more Republish this articleRepublish our articles for free, online or in print, under Creative Commons licence. The leaf-feeding beetle Zygogramma bicolorata is one of the most promising agents used against famine weed in South Africa. Blair Cowie The poisonous herb, Parthenium hysterophorus, is one of the world’s most destructive invasive plants. It threatens biodiversity, national food security and human health. Native to parts of Central and South America (Gulf of Mexico) it has spread to more than 40 countriesincluding Australia, India, Pakistan, Ethiopia, Swaziland and South Africa. In South Africa it’s known as famine weed. Much of southern and eastern Africa remains susceptible to famine weed invasion. First recorded in South Africa in 1880, famine weed only became a prominent invader in 1984 after cyclone Demoina hit the country. Since then, the plant has rampantly invaded northern and eastern parts of the country prompting major concern. Famine weed spreads rapidly and is devastatingly destructive. It kills other plants within its vicinity, wipes out entire crop harvests, poisons wildlife as well as livestock, makes food inedible and causes a variety of health problems in humans. Controlling famine weed is incredibly difficult, but it is possible. A number of approacheshave been trialled and include physical and mechanical removal, herbicide sprays, prescribed fires and biocontrol (using the weed’s natural enemies). So far South Africa is mainly attempting to thwart the spread of famine weed and reduce infestations using biocontrol. Rather than trying to get rid of the weed entirely, biocontrol uses Parthenium’s natural enemies to slow down infestation and spread of the weed. Following biocontrol successes in Australia and India, South Africa become the first African country to implement biocontrol against Parthenium in 2003. The use of biocontrol in South Africa has made some progress in slowing the spread of famine weed, but the battle is never ending. Devastating effects The weed’s rapid growth rate and prolific seed production make it highly troublesome. It’s tiny seeds are easily spread by wind, water, animals, vehicles, or in soil, and can remain...

Read More

Invasive plants have a much bigger impact than we imagine

Invasive plants have a much bigger impact than we imagine

Authors Susana Clusella-Trullas physiological ecologist at the C·I·B, Stellenbosch University Raquel A Garcia Postdoctoral fellow at the CIB, Stellnbosch University, Stellenbosch University Disclosure statement Susana Clusella-Trullas receives funding from National Research Foundation, South Africa. Raquel A Garcia receives funding from the Centre of Excellence for Invasion Biology (CIB). Stellenbosch University provides support as an endorsing partner of The Conversation AFRICA. The Conversation is funded by Barclays Africa and seven universities, including the Cape Peninsula University of Technology, Rhodes University and the Universities of Cape Town, Johannesburg, Kwa-Zulu Natal, Pretoria, and South Africa. It is hosted by the Universities of the Witwatersrand and Western Cape, the African Population and Health Research Centre and the Nigerian Academy of Science. The Bill & Melinda Gates Foundation is a Strategic Partner. more Republish this articleRepublish our articles for free, online or in print, under Creative Commons licence. Invasive pine trees in the Western Cape have affected lizards causing their numbers to drop significantly. Author supplied   This article is the fifth in a series The Conversation Africa is running on invasive species. Most people would agree that invasive plants are unwanted. Invasive plants are plants that are intentionally or accidentally introduced by humans into areas outside of their natural habitat. These species can spread rapidly with negative consequences for native species. Invasive plant species have an impact on the diversity of local species, they affect water availability and damage the quality of soil nutrients. Once an alien plant has invaded a habitat, it changes the conditions of that environment. It does so by changing the light, solar radiation and temperature levels in the invaded patches. The quality and availability of food, shelter, nest sites, basking sites and perches are changed for a number of animals. They can also inflict big changes on native vegetation, altering the frequency of fires, nutrient cycling, water availability and soil erosion. For example, pine trees in the Western Cape Province of South Africa have spread beyond forestry plantations and invaded native fynbos habitat. In these invaded landscapes, the temperatures available to lizards for functioning optimally are generally cooler and the number of lizard species greatly reduced. In a few cases, some benefits of alien plants have been reported. For example, they can provide fire wood for local communities or add resources for animal species. But these benefits typically do not surpass the negative effects. Invasive plants have an impact on native species through complex interactions and processes. Unless these factors are properly understood, it is difficult to predict what sort of impact invasive plants will have. How much is known about these processes in South African habitats, where invasive alien plants are a key concern? To find the answer, we read all the studies on the impact...

Read More

Peanut butter cassia

Peanut butter cassia

These pests are springing up all over Paradise Ridge. It literally grows like topsy - six months ago the seed germinated, now they are mature plants, standing a meter high, in full bloom and laden with seedpods. It is a very attractive plant, water wise and pest free, but please don't be tempted to retain it in your garden. They are extremely invasive and toxic to humans and animals. Peanut butter cassia: Senna didymobotrya Common name: Peanut butter cassia Scientific name: Senna didymobotrya (Fabaceae) Alternative common names: Oatmeal cassia, popcorn senna, wild senna (English); grondboontjiebotterkassia (Afrikaans); munwahuku (Shona) An evergreen, rounded shrub or small tree reaching up to 3m high. The young shoots are softly downy and 5cm long. Bright yellow flowers form in upright racemes. Green seed pods are downy, soft and flattened and turn dark brown. This senna has poisonous leaves. Additional Info Where does this species come from? Tropical Africa What is its invasive status in South Africa? CARA 2002 – Category 1 NEMBA – a. 1b in Eastern Cape, KwaZulu-Natal, Limpop, Mpumalanga and Western Cape. b. Not listed elsewhere. Where in South Africa is it a problem? KwaZulu-Natal, Mpumalanga, Limpopo and Eastern Cape How does it spread? Seeds Why is it a problem? Environmental and other impactsSenna didymobotrya is capable of forming dense impenetrable thickets that impede the growth and regeneration of native plants and affects the movement of wildlife. It invades grasslands, woodlands, forests, riparian zones (banks of watercourses) and coastal scrub. S. didymobotria can be termed a “bush encroacher”, a African  species that has become invasive. Such plants are likely to exist in a stable balance under natural conditions. However, under human-induced changes such as overgrazing, such species can increase in density to the detriment of other vegetation. Poisonous What does it look like? General description: A wide-spreading evergreen shrub to small tree growing up to 3m in height. Leaves: Dark green leaves with 8-21 pairs of leaflets in opposite pairs 2-5cm long. Flowers: Bright yellow flowers in upright racemes prevalent throughout the year. Fruit/seeds: Green pods turning dark brown that are softly downy and flattened Share this:Click to email this to a friend (Opens in new window)Click to print (Opens in new window)Click to share on Facebook (Opens in new window)Click to share on Twitter (Opens in new window)Click to share on Reddit (Opens in new...

Read More

TEAM TAUGHT TO KILL INVASIVE ALIEN PLANTS

TEAM TAUGHT TO KILL INVASIVE ALIEN PLANTS

Ecoguard’s Peter Emslie demonstrates the correct method of mixing herbicides at an alien vegetation management seminar and herbicide applicator training session held in Brenton-on-Sea recently. Photo: Martin Hatchuel KNYSNA NEWS – The Environmental Management Workstream of the Garden Route Rebuild Initiative (GRRI) has implemented a pilot project to train a team of previously unemployed people in invasive alien plant eradication. The team attended an alien vegetation management seminar and herbicide applicator training session presented by the Southern Cape Landowners Initiative (SCLI), the Southern Cape Fire Protection Association (SCFPA), and the herbicide research and supply company, Ecoguard, in Brenton-on-Sea last week. “We’ve established this team of 24 people to help achieve the aims of the three priority projects of the Environmental Management Workstream: post-fire soil erosion mitigation, invasive alien plant control, and the establishment of fire breaks around communities still at risk,” said the SCFPA’s Paul Buchholz, who is also the project manager of the GRRI’s Environmental Management Workstream. Buchholz said that all team members have received training as brush-cutter operators, and in the application of herbicides, and that selected members will now be trained as chainsaw operators. Partnerships The Environmental Management Workstream is looking for partners to assist with the implementation of important projects such as post-fire invasive alien plant control. The invasive alien eradication team was established “as a result of a partnership between multiple players – including the Fund for the Reconstruction of Knysna and the Garden Route, the SCFPA, the Department of Environmental Affairs, the Eden District municipality, private companies like Ecoguard, and various landowners,” said Buchholz. “Partnerships will become increasingly important as the rebuild gathers momentum, because no single organisation could achieve all that we have to do, and no single institution can have sufficient resources to tackle all the environmental, socioeconomic and other challenges facing the region at the moment,” he said. “Besides achieving the immediate aim of preparing the team so that we can start using them on the ground, this programme is important because it’s providing the individuals involved with skill sets that will assist them to find work in the open market if they choose to move on,” said Buchholz. Read more on www.gardenrouterebuild.co.za ARTICLE: MARTIN HATCHUEL Share this:Click to email this to a friend (Opens in new window)Click to print (Opens in new window)Click to share on Facebook (Opens in new window)Click to share on Twitter (Opens in new window)Click to share on Reddit (Opens in new...

Read More