Jimmy O. Pittchar

Achieving food security for one million sub-Saharan African poor through push–pull innovation by 2020

Food insecurity is a chronic problem in Africa and is likely to worsen with climate change and population growth. It is largely due to poor yields of the cereal crops caused by factors including stemborer pests, striga weeds and degraded soils. A platform technology, ‘push–pull’, based on locally available companion plants, effectively addresses these constraints resulting in substantial grain yield increases. It involves intercropping cereal crops with a forage legume, desmodium, and planting Napier grass as a border crop. Desmodium repels stemborer moths (push), and attracts their natural enemies, while Napier grass attracts them (pull). Desmodium is very effective in suppressing striga weed while improving soil fertility through nitrogen fixation and improved organic matter content. Both companion plants provide high-value animal fodder, facilitating milk production and diversifying farmers’ income sources. To extend these benefits to drier areas and ensure long-term sustainability of the technology in view of climate change, drought-tolerant trap and intercrop plants are being identified. Studies show that the locally commercial brachiaria cv mulato (trap crop) and greenleaf desmodium (intercrop) can tolerate long droughts. New on-farm field trials show that using these two companion crops in adapted push–pull technology provides effective control of stemborers and striga weeds, resulting in significant grain yield increases. Effective multi-level partnerships have been established with national agricultural research and extension systems, non-governmental organizations and other stakeholders to enhance dissemination of the technology with a goal of reaching one million farm households in the region by 2020. These will be supported by an efficient desmodium seed production and distribution system in eastern Africa, relevant policies and stakeholder training and capacity development.

Delivering sustainable crop protection systems via the seed: exploiting natural constitutive and inducible defence pathways

To reduce the need for seasonal inputs, crop protection will have to be delivered via the seed and other planting material. Plant secondary metabolism can be harnessed for this purpose by new breeding technologies, genetic modification and companion cropping, the latter already on-farm in sub-Saharan Africa. Secondary metabolites offer the prospect of pest management as robust as that provided by current pesticides, for which many lead compounds were, or are currently deployed as, natural products. Evidence of success and promise is given for pest management in industrial and developing agriculture. Additionally, opportunities for solving wider problems of sustainable crop protection, and also production, are discussed.

Push–Pull: A Novel IPM Strategy for the Green Revolution in Africa

Africa faces serious challenges in feeding its population, mainly due to poor yields of cereals that serve as both staple and cash crops occasioned by insect pests, weeds, and poor soil fertility, and more recently effects of climate change. A novel IPM approach dubbed “push–pull” has been developed and implemented in eastern Africa, based on locally available companion plants, that effectively addresses these constraints resulting in substantial grain yield increases. The technology involves intercropping cereal crops with stemborer moth repellent crops (push), the forage legume desmodium or molasses grass, and planting the attractive Napier grass (pull) as a border crop. Desmodium is very effective in suppressing striga weed while improving soil fertility through nitrogen fixation and improved organic matter content. The companion plants provide high-value animal fodder, facilitating milk production and diversifying farmers’ income sources. The technology, currently practiced by over 55,000 farmers in East Africa, has been adapted to dry conditions associated with climate change by identifying and incorporating drought-tolerant companion plants. The development of this technology, its benefits and subsequent efforts to expand its geographical suitability and effectiveness are described.

Climate-smart push-pull: a conservation agriculture technology for food security and environmental sustainability in Africa

This chapter describes the push-pull technological innovation developed by the International Centre of Insect Physiology and Ecology (ICIPE) in the UK and partners in East Africa, which addresses smallholder agricultural constraints, food insecurity, and environmental degradation and has the potential to equip farmers with the resilience and adaptability they need to deal with climate change. The push-pull technology fits conservation agriculture (CA) principles of minimum soil disturbance in its minimum soil tillage agronomic management, continuous soil cover with a perennial cover crop and plant residue, as well as a diversified cereal-legume-fodder intercropping strategy. The perennial intercrop provides live mulching, thus improving above-ground and below-ground arthropod abundance, agrobiodiveristy and the food web of natural enemies of stem borers, thus effectively controlling major insect pests of cereals. The field implementation of this technological innovation in Africa is discussed, as well as its various benefits.

Exploiting Phytochemicals for Developing Sustainable Crop Protection Strategies to Withstand Climate Change: Example from Africa

Africa suffers chronic food insecurity resulting from ravaging effects of insect pests, weeds and poor soil fertility, with rising poverty and increasingly dry and hot weather conditions associated with climate change further aggravating this situation. Scientists at the International Centre of Insect Physiology and Ecology (icipe) together with national and international partners have developed a platform technology, ‘push–pull’, based on locally available companion plants for integrated management of these constraints by exploiting innate plant defence systems including secondary metabolism. This involves intercropping cereal crops, the main staple and cash crops for millions of smallholder farmers in the continent, with forage legumes in the genus Desmodium and planting Napier grass as a trap plant around this intercrop. Stemborer pests are attracted to Napier grass (pull) and are repelled from the main cereal crop by the repellent desmodium (push). Desmodium root exudates effectively control the parasitic striga weed by causing abortive germination and also improve soil fertility through nitrogen fixation, provide natural mulching and improve biomass. Both companion plants provide high-value animal fodder, facilitate milk production and fetch additional income for farmers. The technology is appropriate to smallholder mixed cropping systems in sub-Saharan Africa (SSA) as it effectively addresses major production constraints and significantly increases cereal yields. It is currently being practiced by about 90,000 smallholder farmers in eastern Africa and has also been adapted to harsh conditions associated with climate change by incorporating drought-tolerant companion plants. This chapter highlights the developmental process of the technology and its benefits in SSA in the face of climate change.