Wheat varietal change and adoption of rust resistant wheat varieties in Ethiopia from 2009/10 to 2013/14

Abstract

This study tracks wheat varietal adoption by farmers in Ethiopia from 2009/10 to 2013/14 and was based on two nearly identical national wheat variety adoption studies undertaken by EIAR and the International Maize and Wheat Improvement Center (CIMMYT) over a four-year period. A total of 2,096 households were surveyed in 2009/10 and 1,921 (all from the preceding survey) in 2013/14. Three potentially significant factors influenced Ethiopian wheat farmers during the four-year period between surveys. First, in 2010/11 one of the most devastating stripe (yellow) rust epidemics in recent times hit many of Ethiopia’s wheat growing regions. Second, on-going investments by national and international organizations helped to develop, promote, and popularize improved rust resistant wheat varieties. Third, a new stem rust race (race TKTTF) was detected in Ethiopia for the first time in 2012. Forty-two percent of the surveyed households were affected by the 2010/11 stripe rust epidemic, and 40% of the affected households discontinued using the old wheat varieties and replaced them with alternative varieties in the next production season. Survey results showed a substantial shift in varietal use over the four-year period. Previously dominant cultivars 'Kubsa' and 'Galema' became highly susceptible to stripe rust in 2010/11 and declined in area share. These two varieties alone accounted for 29.5% of the total wheat area surveyed in 2009/10. By 2013/14, they only accounted for 18% of the total wheat area surveyed (with 'Galema' accounting for only 1.4%). Varieties considered rust resistant (namely; 'Digalu', 'Kakaba', 'Danda’a', 'ET-13', 'Pavon-76' and 'Mada Walabu') occupied 47% of the total wheat area surveyed in 2013/14. The biggest area increases were recorded for the new rust resistant varieties 'Digalu', 'Kakaba', and 'Danda’a'. Most notable was the increase in the area planted to ‘Digalu’, which alone covered 27.1% of the wheat area surveyed in 2013/14 (vs. only 2.1% in 2009/10). The shift to growing ‘Digalu’ was most pronounced in the central and southern regions of Oromia and the Southern Nations, Nationalities, and Peoples’ Region (SNNPR), but increased cultivation was also recorded in the northern regions of Amhara and Tigray. The main reason for expanding cultivation of ‘Digalu’ was its resistance to stripe rust. Most of the overall change in varieties’ area coverage was observed in hot to warm sub-humid lowland (SH1) agro-ecologies, followed by tepid to cool humid mid-highland (H2) agro-ecologies; both are conducive environments for rust development and occurrence. Reported total average wheat yields showed a modest and non-significant increase of 3% in 2013/14 (1.75 t/ha) compared to 2009/10 (1.70 t/ha). However, despite rising input costs over the four-year period, wheat production significantly increased the average net income of the surveyed farmers: 5,339 Birr/ha in 2013/14, compared with 4,320 birr/ha in 2009/10. The current comparative study illustrates the widespread and rapid turnover of wheat varieties within the four-year period. A major stripe rust epidemic in 2010/11 was undoubtedly a key driver of change, but effective promotion and widespread availability of seed of alternative rust resistant varieties were also important. Recent investments to support varietal development and the promotion of rust resistant varieties undoubtedly played a role in making rapid varietal change possible. Wheat farmers in Ethiopia benefited from the varietal changes with productivity gains and increasing incomes. However, the risk of over-relying on a mega variety protected by single major gene resistance --‘Digalu’ in this instance-- in the rust prone Ethiopian farming system was clearly revealed. While maintaining good resistance against the prevailing stripe rust and Ug99 stem rust races, ‘Digalu’ is now highly susceptible to TKTTF, the latest stem rust race to be detected in Ethiopia. As a result, replacement of ‘Digalu’ is a high priority. Rust epidemics are a driving force for the replacement of susceptible varieties. The current study shows that rapid varietal replacement is possible in Ethiopia; however, it must be done in a concerted, coordinated, and strategic manner. Emphasis should be placed on ensuring that a genetically diverse range of varieties is popularized and put in the hands of farmers. As much as possible, a range of durable, race-nonspecific rust resistant varieties should continue to be developed and deployed, while avoiding single major gene-based resistance. These rust resistant varieties should be targeted to the highest rust prone agro-ecologies. Continuous monitoring of the rust populations in Ethiopia and the surrounding region is essential to ensure that new disease threats are detected as soon as possible and important races are used for screening by breeding programs to enable testing and development of new, improved, resistant varieties.