Johannesburg - Identifying and remove any of the 306 invasive alien plants listed in local legislation from your garden. Gardens devoid of invader plants contribute positively towards biodiversity conservation.
“Invasive alien species represent the second most significant cause of species extinction worldwide after habitat destruction,” states the International Union for Conservation of Nature (IUCN).
Invasive alien plants compete for the same resources and in many instances completely displace our indigenous plants. This in turn negatively affects animal communities which rely on indigenous vegetation for food and shelter.
What should you be looking out for? Joburg gardens are prone to invasion by the following plants: bugweed (Solanum mauritianum); Chinese wax-leaved privet (Ligustrum lucidum); cat’s claw creeper (Dolichandra unguis-cati); lantana (Lantana camara); yellow bells (Tecoma stans); inkberry (Cestrum laevigatum); pampas grass (Cortaderia selloana); moth catcher (Araujia sericifera); queen of the night (Cereus jamacaru) and pompom weed (Campuloclinium macrocephalum).
Celebrating biocontrol
2013 marks the centenary of biocontrol in South Africa. The first biocontrol project was initiated against the drooping prickly pear (Opuntia monocantha) in 1913.
Since then, biocontrol scientists have celebrated huge success in combating some of South Africa’s worst invasive species. One of the biggest successes has been the biocontrol of the highly invasive water hyacinth (Eichhornia crassipes), an aquatic weed from South America, which has invaded many water features, rivers and dams. Today there are eight biocontrol agents keeping water hyacinth under control.
One of the latest agents is an aquatic grasshopper called Cornops aquaticum. Females insert egg cases into the base of the petioles and the nymphal instars feed on the leaves, causing extensive damage. The cornops grasshopper will be launched at a Ministerial National WeedBuster event in Grahamstown on Wednesday.
How does biocontrol work? Biocontrol is all about importing a plant’s natural enemies from their country of origin. After the insects undergo stringent testing in quarantine, they are released on to the host plant. These agents include mites, insects and fungi, which cause damage to various parts of the host plant. Careful research is conducted by scientists to ensure that the agent only feeds on the targeted plant and that no indigenous plants are harmed.
Biocontrol is deemed as one of the most effective and economically viable long-term control measures to hinder and suppress the growth of unwanted plants. In some cases, 100 percent control can be achieved.
There are now a number of insect-rearing stations around the country, which harvest biocontrol agents. As the distribution becomes more sophisticated, garden centres and gardeners could be part of the supply chain.
WeedBuster Week represents the annual culmination and highlight of the ongoing campaign aimed at the management and containment of invasive alien plants. The campaign is a multi-departmental initiative led by the Department of Environmental Affairs through environmental programmes. See www.invasives.org.za
GENERAL GARDENING TIPS
* The smallest garden or balcony can find space for a couple of pots, a hanging basket or a window box for salad greens, baby cabbages, cherry tomatoes and flavourful herbs.
* World Food Day on October 16 reminds us of the need for food security. Make your garden more diverse and useful by growing fruit trees, nutritious vegetables and herbs, as well as edible flowers. If you have space for only one fruit tree, plant a lemon tree. They are not only decorative, they are also rich in Vitamin C, so necessary for health.
* In an open-plan office, tall potted plants of bamboo or ficus can be used as living screens. Sanseveria (mother-in-law’s tongue) will grow in bright light. Medium light suits most ferns and foliage plants such as calathea, caladium and maranta, while aglaonema, the peace lily and aspidistra will grow in low light.
* In semi or filtered shade add splashes of colour with impatiens, browallia, torenia, fuchsia and bedding begonias. Very few flowering plants will grow in deep shade. Rather grow foliage plants such as aucuba, coleus, ferns or green and white striped hen-and-chickens. - Saturday Star