In an important new development, scientists from around the world have come together to find a solution to the water hyacinth invasion that has reached crisis point in many parts of the world. Water hyacinth, an invasive weed choking major freshwater lakes and rivers across Africa, South East Asia, India, China and the USA, is a native of South America. It was introduced into Africa in the 19th century, probably as an ornamental pond plant, but found its way into lakes, rivers and canals where it proliferated. Without the natural enemies that would normally inhibit its spread, it has become a major problem in many tropical and subtropical regions.
Water hyacinth grows on the water's surface as a dense mat up to a metre high.
It is a serious problem, particularly for developing countries, clogging up waterways, dams, ports, landing areas, hydroelectric turbines and irrigation systems essential to economic development. In the worst affected areas, such as Lake Victoria in Africa, commercial shipping is hindered, the livelihoods of fishermen have been wrecked, the biodiversity of rivers and lakes have been depleted, low water levels are exacerbated by increased evapotranspiration through the plant's leaves, the daily business of collecting water and washing in rivers and lakes has become a dangerous one with crocodiles lying in wait beneath the dense cover of vegetation, and the stagnant waters around the shorelines have become a breeding ground for malarial mosquitoes and the snail hosts of bilharzia. Conventional methods of controlling the weed, involving costly and environmentally damaging spraying with chemicals or mechanical clearing, offer only short-term solutions. Long-term biological control methods were first used in the 1970s with the release of natural biological enemies such as weevils, but these take a few years to have a significant effect. The collaborators, from the UK, Kenya, Benin, Eygpt, Zimbabwe and South Africa, will each work with their national programmes to isolate suitable fungal pathogens with similar characteristics.