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Commercialization of sweetpotato vines is persistent if multipliers show evidence of superiority of their vines. This study aimed at evaluating the effects of net tunnel source and of pathogen-tested planting material compared to “apparently” healthy vines on yield and health status at three defined environments in Northern Ghana during the rainy season of 2015. Sweetpotato virus disease (SPVD) and weevils were considered. Four varieties were investigated, the pathogen-tested vines of Dadanyuie, Bohye and Ligri, and “apparently” healthy vines of Apomuden from the negative selection technique. All planting materials taken from the net tunnel and open field were from the same location. Eight treatment combinations were arranged in a RCBD with 3 replicates. Planting distance was 0.30 m x 1 m. Weeding was done and fertilizer was applied as necessary. General and three-way analysis of variance were computed using Genstat. Highly significant differences were found among varieties and trial sites for plant establishment, foliage yield, root yield, weevil, and SPVD. The two sources were not significantly different. For varieties across sites, net tunnel source was better than open field. The apparently healthy vines might be effective as pathogentested vines. Net tunnels may have a distinct advantage for multiplication and maintenance.

Biofortified orange-fleshed sweetpotato (OFSP), rich in beta carotene, is currently being promoted due to its role in fighting vitamin A deficiency. To promote farmer access to OFSP planting material (i.e., vines) projects establish vine multipliers who are expected to operate commercially. However, most sweetpotato farmers are used to getting vines from social networks free of cost. In this study, we compare farmers’ willingness to pay for clean (i.e., pest and disease free) vines of biofortified and popular non-biofortified sweetpotato varieties. The study thus holds vine “health” constant while assessing the influence of vitamin A biofortification on demand. We then use seemingly unrelated regression technique and data from 481 farmers to assess factors affecting the demand for both types of vines. We find higher willingness to pay for clean non-biofortified sweetpotato vines than biofortified sweetpotato vines of similar health, because of the higher nutritional value, good taste, and firmness of the roots of the former. Factors affecting demand for clean vines include the number of children a farmer has, farmer's age, tastes, preferences, sweetpotato yield and income. These effects differ between biofortified and non-biofortified varieties. We conclude that demand for clean OFSP vines is high, but still lower than for white-fleshed varieties, and discuss implications of the findings.

Since the seventies, factors such as declining soil fertility and the emergence of pests and diseases have reduced banana ( Musa spp.) yields from about 10 to 4 t ha-1 in the Kagera region, North Western Tanzania where banana is the most important staple food. Thus, clean planting materials are required to solve the problem of pests and disease infection. To this effect, new banana varieties were introduced, multiplied locally and distributed to more than 0.5 million people since 1997. The target was set to have 1 million plants of superior varieties in the farmer's fields by March 2003 which accounts to about 1.5% of the total banana population in the region. A total of 21 varieties were introduced and evaluated for their palatability and field performance by the local communities. Fourteen varieties were multiplied In vitro . A total of 71,000 In-vitro plants were introduced in the region since 1997 and multiplied in 35 nurseries by field decapitation. These multiplication fields contain 84,000 stools and are spread over the entire region. To-date 340,000 suckers have been distributed by the project and 680,000 suckers from farmer to farmer, amounting to 1,020,000 suckers. The best performing varieties are FHIA-17, FHIA-23, SH3436-9 and Yangambi. Results of an impact assessment survey show that the superior varieties outyield the local varieties by an average of 40%. Key Words: Clean planting material, impact assessment, In-vitro, Musa spp. RESUME Depuis les annees soixante-dix, des facteurs tells que la reduction des la fertilite de sols et l'emergence des pestes et maladies ont reduit le rendement de la banane ( Musa spp.) de 10 a 4 t ha-1 dans la region de Kagera, au nord ouest de la Tanzanie ou la banane est la nourriture de base. Par consequent, du materiel sain est necessaire pour resoudre le probleme d'infection des pestes et des maladies. Pour ce faire, des varietes nouvelles etaient introduites, multipliees localement et distribuees a plus de 0.5 million des personnes depuis 1997. Il etait cible d'atteindre 1 million de plantules de varietes superieures dans les champs des fermiers vers Mars 2003 representant 1,5% de la population bananiere dans la region. Au total 21 varietes ont ete introduites et evaluees pour leur gout et performance dans les champs par les communautes locales. Quarante varietes ont ete multipliees in vitro. Au total 71,000 In-vitro plantes ont ete introduites dans la region depuis 1997 et multipliees dans 35pepiniere par decoupage en champs. Un total de 84,000 coupures ont ete realisees par multiplications dans les champs et ont ete disseminees dans toute la region. Aujourd'hui 340,000 rejetons ont ete distribues par le projet et 680,000 rejetons d'un fermier a l'autre, pour un total de 1,020,000 rejetons. Les varietes les plus performantes sont le FHIA-17, FHIA-23, SH3436-9 et Yangambi. Les resultats de l'evaluation de l'impact ont montre que les varietes superieures ont outre passees les varietes locales par une moyenne de 40%. Mots Cles: Materiel de plantation sain, evaluation de l'impact, In-vitro, Musa spp. African Crop Science Journal Vol.12(1) 2004: 7-17