Invasive weed ‘could cut crop yields by 30 per cent’

[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 reduce crop yields, scientists say.

A scientist who has been studying the toxic weed for a decade in Africa estimates that over US$1.1 billion will be needed for research on how to completely eradicate the weed and to mobilise farmers and policymakers to tackle the scourge.

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

“It will be nearly impossible to control this weed in the next decade if national governments fail to take quick action.”

Innocent Ngare, Kenyatta University

Koske noted that Africa’s economy, unlike other continents, is anchored on agriculture. If not checked early enough, field dodder – known scientifically as Cuscuta campestris – could reduce projected agricultural yields in Sub-Saharan Africa by nearly 30 per cent by 2029, he predicted.

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

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

Field dodder, a yellow weed native to North America, is now spreading in Sub-Saharan Africa at an increasing rate, in countries such as Botswana and Ethiopia, said Ngare. 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 explained. “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 economic blocs in Sub-Saharan Africa to start mobilising financial and human resources urgently to curtail the spread of the stubborn weed.

Julius Otieno, a farmer in Kenya’s Homa Bay County, told 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.”

According to Ngare, herbicides have mostly been used to control the weed in its native continents and in Africa farmers will be forced to use large amount of their income to buy these 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 said.

Oscar Koech, an ecologist and lecturer at the University of Nairobi, says that the weed is a major ecological threat that governments must act fast to quash.

“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,” said 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.