Deadly striga weed spreading across Eastern Africa

Maina Waruru in SciDev.net: Rising soil temperatures are increasing the spread of a deadly, parasitic weed that significantly reduces crop yields in Sub-Saharan Africa, Striga, according to scientists. The noxious weed, also known as witch-weed, usually thrives in the warm and humid tropics but is now spreading to cooler and wetter highlands as a result of warmer soils driven by global warming and low soil fertility, which provides the right conditions for Striga to thrive.

This spread has threatened the livelihoods of around 100 million people, with more than four million hectares of maize crops infected. In general, Striga reduces maize and cowpea yields by up to 80 per cent in Sub-Saharan Africa.

Some farmers are now abandoning maize cultivation for cassava as the parasitic plant colonises areas at attitudes more than 1,500 metres above sea level, said Mel Oluoch, head of the Integrated Striga Management in Africa programme at the International Institute of Research in Tropical Agriculture (IITA), during a farmers' field day in Western Kenya last month (17 January) organised by ISMA.

"Striga currently remains the biggest threat to maize production, particularly in the East Africa region where corn is the staple for millions of inhabitants," said Oluoch, adding that the weed devastates plants by attaching itself at the root base, starving the host for nutrients.

"More worrying is that the weed is spreading fast to areas not traditionally known to be infected, owing to climate change-related impacts and the resulting rise in soil temperatures coupled with low soil fertility across most of Africa," Oluoch told SciDev.Net and added that they have been observing the weed for more than two years...

Corn in Kenya, from USAID's Africa bureau