Nonchemical weedkiller has huge potential
Hungriest nations may benefit thanks to McGill plant scientists.
McGill University plant scientist Dr Alan Watson and research associate Marie Ciotola in the Faculty of Agricultural and Environmental Sciences believe they can help farmers in Africa recover desperately needed agricultural land invaded by a noxious weed known as Striga, or witchweed. Field trials in Mali led by the Biopesticide Research Laboratory have produced spectacular results using a naturally occurring pathogen, Fusarium. "Most of the Striga was wiped out and crop yields doubled," says Dr Watson. Not only that, the researchers figured out a way to manufacture the Fusarium locally, which provides farmers and women in the community with more economic and social power.
Currently one of the greatest obstacles to food production in Africa, the parasitic Striga, described as "a pretty flower but a deadly weed," thrives in areas of poor soil and infests two thirds of land devoted to cereal crops. "The losses can be as high as 70% among subsistence farmers," says Dr Watson. The weed compensates for its own lack of root system by penetrating the roots of other plants and stunting their growth.
Dr Watson and his colleagues evaluated 250 organisms and were gratified to find that the Fusarium pathogen attacked the seeds as well as the plant. The next challenge was to find a way to make the fungus available to farmers. Researchers came up with a starter culture in a capsule, which could be fermented and dried locally. The farmers have their seed coated first with wet arabic gum, which acts as an adhesive, and then with the Fusarium inoculant. Once the seeds are planted, the rain activates the Fusarium inoculant and makes it available exactly where it is needed: at the roots of the cereal plant.
"Using inexpensive, locally available ingredients like sorghum straw and arabic gum, the process of preparing the dried fungus involves cooking pots and boiling water, womens traditional sphere of work. It also provides a new source of income for them," explains Watson. A socio-economic survey of 100 farms conducted by the McGill team showed that village women could indeed produce the Fusarium on a cottage industry-type scale, coat batches of seed for individual farmers, and sell the service to the local growers.
The McGill plant scientists work was carried out under the auspices of the People, Land and Water program of the International Development Research Centre (IDRC). The program focuses on soil productivity and water management to provide secure sources of food, water and income for rural people in Africa and the Middle East. It is unique because it takes into account the knowledge, needs and desires of the people directly affected by the scarcity of arable land and water. The future is hopeful, say the researchers who are working with IDRC to introduce Fusarium to other countries afflicted with Striga. Congratulating both the Watson team and IDRC, Dr Deborah Buszard, dean of McGills Faculty of Agricultural and Environmental Sciences notes proudly, "Making the knowledge and technology freely available in the developing world is a real contribution to improving the human condition."