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Staking in forest zone

Production costs are high in traditional yam based cultivation systems in West Africa However the benefit-cost ratios are highly favorable. Mounds in savanna zone. Staking in forest zone. Staking in savanna zone. (Benefit-cost ratio for yam cultivation in Nigeria = 3.89). Preparing a mound.

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Staking in forest zone

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  1. Production costs are high in traditional yam based cultivation systems in West Africa However the benefit-cost ratios are highly favorable. Mounds in savanna zone Staking in forest zone Staking in savanna zone (Benefit-cost ratio for yam cultivation in Nigeria = 3.89)

  2. Preparing a mound Several yam stands using a tree as support Dioscorea cayenensis staked on a ridge Yams in East Africa: selected cultivation practices

  3. D. cayenensis harvest in Tanzania

  4. Major Pests and Diseases • Nematodes (Scutellonema bradys; Meloidogyne spp.) • Mealybug (Planococcus spp., Phenacoccus spp.) • Scale insect (Aspidiella hartii) • Tuber rots (e.g. Botryodiplodia, Fusarium, etc.) • Anthracnose (Colletotrichum gloeosporiodes) • Viruses (YMV, DAV)

  5. Symptoms and damage caused by yam anthracnose disease (bottom right photo shows contrast between susceptible varieties that are almost dead and resistant ones growing)

  6. A range of viruses cause yield losses in susceptible yam varieties Diseased Normal Diseased

  7. Genotype Before After mechanical After vector inoculation inoculation* transmission ELISA ELISA Symptoms ELISA Results Results Results TDr 747 + TDr 179 - ++ Mosaic + None - TDr 1640 - - *Tested for both local and systemic infection ++ = strong positive, + = positive for infection, - = negative for infection. IITA scientists and their partners are finding and incorporating sources of host plant resistance to virus in yam new varities Reaction of D. rotundata landraces to inoculation with YMV

  8. Mealybugs Scale insects Yam beetles Tuber moth damage Insect pests of yam tubers reduce tuber food quality and market value and sometimes completely destroy the tuber.

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