Global severity of potato late blight was estimated by linking two disease forecast models, Blitecast and Simcast, to a climate data base in a geographic information system (GIS). The disease forecast models indirectly estimate late blight severity by determining how many sprays are needed during a growing season as a function of the weather. Global zonation of estimated late blight severity was similar for both forecast models, but Blitecast generally predicted a lower number of sprays. With both forecast models, there were strong differences between potato production zones. Zones of high late blight severity include the tropical highlands, western Europe, the east coast of Canada and northern USA, south-eastern Brazil and central-southern China. Major production zones with a low late blight severity include the western plains in India, where irrigated potato is produced in the cool dry season, northcentral China, and the north-western USA. Using a global GIS data base of potato production, the average number of sprays was calculated by country. These averages were compared with estimates of current fungicide use. The results using Blitecast and Simcast were correlated but only Blitecast estimates correlated with observed data for developed countries. The estimated number of sprays, whether from Blitecast or Simcast, did not correlate with the observed number of sprays in developing countries, and in a number of developing countries the predicted optimal number of sprays was much higher than the actual number observed. In these countries, increased access to host resistance and fungicides could have a strong economic impact.

This chapter focuses on the potential contributions of modern cultivar change to agricultural development in Africa south of Sahara. The direct positive consequences of the use of improved cultivars for food security are discussed and the role of modern cultivar change in setting the stage for the adoption of more intensive crop production practices, such as row planting, and as a precursor to the judicious use of purchased inputs that spark multiplier effects for economic growth are highlighted.

Parallel to the preceding chapter, we synthesize the results of Chapters 6-17 here. The focus is on outcomes and impacts. Outcomes centre on varietal adoption and turnover; impacts refer to changes in on-farm productivity, poverty and food security. Hypotheses from Chapter 3 are revisited at the end of each thematic section. Varietal Adoption By crop The area-weighted grand mean adoption level of improved varieties in Sub-Sharan Africa (SSA) across the 20 crops in the project is 35% (Table 19.1). Two-thirds of the crop entries in Table 19.1 fall below the mean estimate. Starting at the bottom of the table, the limited uptake for improved field pea, which is produced primarily in Ethiopia, is not surprising. Internationally and nationally, field pea is arguably the crop species in Table 19.1 that has had the smallest amount of resources allocated to its improvement. In contrast, both chickpea and lentil have benefited from international agricultural research in the CGIAR (Consultative Group on International Agricultural Research) since the earlyto-mid-1970s. Although progress has been made, adoption of improved cultivars of both crops is concentrated in small pockets of production regions in Ethiopia where extension programmes have been active (Yigezu et al., 2012a). This apparent location specificity is typical of pulse crops, but it is surprising in light of improved lentil varieties that have reportedly significantly heavier yields than their local counterparts. Adoption levels of faba bean and chickpea are buoyed by a reportedly higher penetration of improved varieties in the Sudan. Indeed, chickpea in the Sudan is the only crop-by-country observation to have been at full adoption level in 2010, albeit on a very small area of 21,000 ha

SummaryWe examine the changing character of supply and demand for potatoes over time and space with an eye towards implications for agricultural research. Diversification in consumption and specialization in production are our organizing themes. The foundation for comparative analysis is a map of the global distribution of potato growing area. We highlight the adverse impact of price risk on specialization and discuss several sources of uncertainty that condition the size but not the direction of major trends.

This chapter focuses on the assessment of the cultivar output, adoption and change for cassava, cowpea, soyabean and yam for Africa south of Sahara and maize improvement in West and Central Africa. The evaluation of the performance of genetic improvement programmes in these crops are also discussed.

The concept of, and evidence for, regional adoption ceilings is assessed for modem coarse cereal cultivars in India. Adoption is defined as the proportion of total area of a given coarse cereal planted to modem cultivars. Agroclimatic and soil differences are more important than disparities in infrastructure in explaining the variation across regions in estimated adoption ceilings. Qualitatively different modem cultivars from those now released are necessary to change regional adoption behavior. The results support an agricultural research strategy that gives higher priority to more regionally oriented breeding and testing programs in preference to the past emphasis on wide adaptation.

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Private investment in plant breeding has been increasing while public plant breeding has stagnated or declined. Moreover, research investment among crop commodities is uneven. Using a comprehensive survey of U.S. plant breeders from 1994, we use a simultaneous equations model to examine incentives and public-private tradeoffs in plant breeding research among 84 crop commodities. Allocation of private breeders among crops is strongly influenced by market size, hybrid seed technology, and ease of breeding improvement. In general, the allocation of public breeders does not appear to “crowd out” private breeders, but some competition may occur in applied breeding. Public breeding declines as private breeding increases on a commodity. Public breeding is also affected by market size, ease of breeding improvement, and political influence.