Bibliography

An overview will be provided of the prospects for the biological control of the rhizomatous grass Imperata cylindrica [(L.) Raeuschel]. Imperata cylindrica is an undisputed target for control technologies in West Africa as it reduces crop yields and causes the abandonment of agricultural land for resource poor farmers. Biological control can provide an environmentally friendly, sustainable and selective method that will be adopted if it provides advantages over alternative control strategies. The influence of variation between biotypes of I. cylindrica will be considered in relation to their control by a single biological organism. The potential of fungal pathogens recovered from surveys in West Africa will be evaluated including Colletotrichum caudatum, Drechslera gigantea, Exserohilum rostratum, Glomerella cingulata and Puccinia rufipes. Malaysian isolates of C. caudatum have previously been tested as a biocontrol agent against the biotype there and isolates of D. gigantea and E. rostratum from USA were included in bioherbicide preparations against an USA biotype of I. cylindrica. Puccinia rufipes could potentially control this weed; as it is a biotroph, it is likely to act as a physiological sink to deplete the carbohydrate reserves stored in the rhizomes. It is the mobilisation of this stored carbohydrate which facilitates this weed’s competitive advantage to rapidly produce leaves following disturbance to the ecosystem, such as in slash and burn agriculture. This rust pathogen has also been observed, along with other biotrophs, in South Africa, where I. cylindrica is not considered a weed.