Agricultural researchers in sub-Saharan Africa are making progress towards ridding the region of the deadly parasitic weed—Striga that infests cereals such as maize and cowpea farms—by developing sustainable, multi-pronged management options that smallholder farmers could effectively and profitably deploy in their farms.
Striga is a crop parasite that is considered to be one of the biggest constraints to agriculture in sub-Saharan Africa. Also known as the violet vampire because of the beautiful violet flowers it produces, the Striga weed mostly affects cereals such as maize and legumes such as cowpea grown in the region. Farmers regularly lose 40 to 100 percent of their crops, with total losses amounting to about US$1.2 billion every year and affecting the livelihoods of more than 25 million smallholder farmers.
The pest sucks and drains its host of water and vital nutrients to the point that the infested plant withers and dies. What makes Striga much more deadly is that it does most of its damage underground, even before emerging and being visible to farmers above the soil surface. By the time the weed and its tell-tale violet flowers appear, it’s already too late? there is not much that farmers can do to save their crop.
Striga produces hundreds of thousands of seeds per plant, leading to massive build-up in the soil that can remain viable for many years. To control this parasitic weed, farmers commonly use cultural methods and post-emergence herbicides, which are largely ineffective in protecting the crop as most of the damage has already been done below the ground/underground. Although this may provide some relief against Striga, the herbicides are nonselective, and are too costly and unavailable for most farmers to use in the long run.
In June 2011, a private public partnership coordinated by the International Institute of Tropical Agriculture (IITA), launched a collaborative effort known as the Integrated Striga Management in Africa (ISMA) project, to develop a package of Striga control options for smallholder farmers in Kenya and Nigeria. The project is funded by the Bill & Melinda Gates Foundation and is being implemented in partnership with the International Maize and Wheat Improvement Center (CIMMYT), International Centre of Insect Physiology and Ecology (icipe), African Agricultural Technology Foundation (AATF), BASF Crop Protection, and national agricultural research and extension services and private sector players in Kenya and Nigeria. ISMA’s main goal is to promote proven Striga management technologies that can be deployed and work in smallholder farming conditions.
The four-year project focuses on improving access to Striga control solutions that include using Striga-resistant maize and cowpea varieties, deploying a “push-pull’ technology that involves intercropping cereals with specific Striga-suppressing forage legumes, using maize varieties resistant to Imazapyr—an herbicide used in coating the maize seeds (StrigAway®) and which kills the Striga seed as it germinates and before it can cause any damage— encouraging maize-legume intercropping and crop rotation; and adopting Striga biocontrol technologies. A significant component of the ISMA project is the identification of best-bet combinations of the available Striga control options for specific socio-ecological targeting.