Africa: Invasive Weed Could Cut Crop Yields By 30%

16 April 2019

Busia, Kenya — A dangerous invasive alien weed known as field dodder could be a serious menace to agriculture and biodiversity across Sub-Saharan Africa, and cutting crop yields, scientists say.

A scientist who has been studying the toxic weed for a decade in Africa estimates that over US$1.1 trillion will be needed to research on how to completely eradicate the weed, sensitise farmers and policymakers, particularly parliamentarians to increase funding for agriculture.

James Koske, acting dean of the School of Environmental Studies at Kenya's Kenyatta University, in an exclusive interview with SciDev.Net last month (9 April), said the alien weed is persistently devastating African ecosystem and threatening to wipe out the continent's rich biodiversity.

"Increasing infestation of field dodder on farmlands has reduced quantity of food produced. This poses a challenge to a sustained food supply," adds Innocent Ngare, a doctoral candidate at the Department of Environmental Sciences, Kenyatta University. "Even African nations that have already been infested by the weed are yet to respond. The breakthrough starts with research, funding, awareness creation and fastening policies on plant trade."

According to Kenya-based icipe, it is projected that in Sub-Saharan Africa invasive alien species menace will directly affect the attainment of three Sustainable Development Goals: SDG1 (no poverty) SDG2 (zero hunger) and SDG3 (good health and well-being).

Koske says that African economy, unlike other continents, is anchored on agriculture. If not checked early enough, field dodder, known scientifically as Cuscuta campestris, could adversely impact nearly 30 per cent projected yields from agriculture in Sub-Saharan Africa by 2029.

Ngare explains that field dooder is native to North America. In Sub-Saharan Africa, the yellow weed is spreading at an increasing rate in countries such as Botswana and Ethiopia. The invasive plant is affecting both indigenous and exotic host plant species.

"Global trade has acted as a pathway through importation and export of seeds that are already contaminated," Ngare explains. "Other pathways are trade in plants grown as ornamentals in homesteads, recreational parks and cities, contaminated harvests or flooding where mature seeds are eroded and swept downstream to surrounding areas."

The scientists are calling on key institutions such as the African Development Bank, the African Union and all the economic blocks in the Sub-Saharan Africa to start, as a matter of urgency, mobilising financial and human resources to curtail the spread of the stubborn weed.

Julius Otieno, a farmer in Kenya's Homa Bay County, tells SciDev.Net, "My live fence is almost falling down. Besides that, my grazing land is completely covered by this yellow weed that has adamantly refused to go away.

"I have tried to burn it, bury it and cut it in pieces but it keeps multiplying," he adds.

According to Ngare, herbicides have majorly been used to control the weed in its native continents and in Africa farmers will be forced to use enormous income to purchase these controlling chemicals rather than reinvest in agricultural food production. "It will be nearly impossible to control this weed in the next decade if national governments fail to take quick action of providing resources necessary for the fight against it," he says.

Oscar Koech, an ecologist and a lecture at Kenya's University of Nairobi, says that the weed is a major ecological threat that governments must act fast to curtail its spread.

"Combating the weed at the moment is very challenging. It's like somebody attacking your system and removing your heart. That is what the weed does to the host plants," says Koech, adding that more funding should be set aside for research to stop its spread.

This piece was produced by SciDev.Net's Sub-Saharan Africa English desk.

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