It's pretty to look at, but that doesn't change the fact that water hyacinth is one of the world's most troublesome weeds. New evidence has led researchers at IITA to believe that fungi have the potential to control these and other noxious plants.
Water hyacinth (Eichhornia crassipes) was introduced to Africa as an ornamental plant. In less than 100 years it has spread rapidly across the continent with devastating effects. Plants infesting waterways grow into a tangled mat, which impedes transport and prevents hydroelectricity generation. They also provide breeding grounds for the carriers of diseases such as malaria and bilharzia.
Previously, IITA had controlled water hyacinth through the introduction of weevils that ate the leaves and crown. But a recent biological control study-the first research by IITA on the use of fungi for weed control-has shown that there is an additional way to manage the plant population. An IITA team surveyed water hyacinth sites across West Africa, and collected potential fungal pathogens. Alternaria eichhorniae was selected for further lab testing because it is indigenous to Africa, virulent, and specific to water hyacinth. When formulated into a mycoherbicide, control of the target weed was further improved.
"We can use what is already in nature to our advantage," says IITA plant pathologist Dr Fen Beed. "Host-specific fungal pathogens can be used to control weeds without disrupting other aspects of the environment."
The initial phase of the study was funded by DANIDA, and funding is being sought for the next stage of the project. The ultimate aim is to produce a commercially available mycoherbicide to control water hyacinth.
Additionally, the project has shown the potential for using fungal pathogens to control other African weeds, including speargrass and witchweed. Many countries are currently forced to waste precious time and resources trying to control water hyacinth. An effective mycoherbicide, combined with weevils, will help clear the waterways of West Africa so they can sustain people, and not weeds.