Thousands of farmers in Kenya and Nigeria are successfully battling the invasion in their farms by Striga, a deadly parasitic weed. They are now enjoying higher yields in maize, the number one staple in Kenya and an important cash crop in Nigeria.
The key to managing this weed is to combine sustainable multiple-pronged technology options being advocated by the Integrated Striga Management in Africa (ISMA) project to sustainably eliminate the weed from their fields, says Dr Mel Oluoch, ISMA project manager.
Striga attacks and greatly reduces the production of staple foods and commercial crops such as maize, sorghum, millet, rice, sugarcane, and cowpea. The weed attaches itself to the roots of plants and removes water and nutrients and can cause losses of up to 100% in farmersâ€™ crops. Furthermore, a single flower of the weed can produce up to 50,000 seeds that can lie dormant in the soil for up to 20 years.
The weed is the number one maize production constraint in Western Kenya, and Nigeria, infesting most farmersâ€™ fields.
The management technologies range from simple cultural practices such as intercropping maize with legumes such as groundnuts; crop rotation of maize with soybean which stimulates Striga to germinate but which later dies in the absence of the maize host to latch onto; deploying a â€œpush-pullâ€™ technology that involves intercropping cereals with specific Striga-suppressing desmodium forage legume; using Striga resistant maize varieties; and using CIMMYT-developed maize varieties resistant to Imazapyrâ€”a BASF herbicide (StrigAwayÂ®), which kills the Striga seed as it germinates and before it can cause any damage; and adopting Striga biocontrol technologies which uses a naturally occurring host-specific fungal pathogen that kills the Striga at all stages without affecting other crops.
Imazapyr-resistant maize varieties with natural resistance to Striga hermonthica have been developed. The best hybrids produce 19% to 333% more grain yields under Striga infestation, sustain 17% to 57% less Striga damage, and support 63% to 98% less emerged Striga plants compared with the commercial hybrid check. In addition, new Striga resistant hybrids and open-pollinated synthetic varieties (OPVs) that combine Striga resistance with good standability have been developed. The hybrids and OPVs produce 47% to 126% more grain yields under Striga infestation, sustain 17% to 60% less Striga damage, and support 45% to 90% less emerged Striga plants compared with the common farmersâ€™ varieties and commercial hybrids.
ISMA (http://www.iita.org/web/striga/) is funded by the Bill & Melinda Gates Foundation and is being implemented with the International Center of Insect Physiology and Ecology, CIMMYT, African Agricultural Technology Foundation, BASF Crop Protection, and other national agricultural research and extension services and private sector players in Kenya and Nigeria.