19 20Seed systems are critical for deployment of improved varieties, and serve as major 21

Seed systems are critical for deployment of improved varieties but also can serve as major conduits for the spread of seedborne pathogens. As in many other epidemic systems, epidemic risk in seed systems often depends on the structure of networks of trade, social interactions, and landscape connectivity. In a case study, we evaluated the structure of an informal sweet potato seed system in the Gulu region of northern Uganda for its vulnerability to the spread of emerging epidemics and its utility for disseminating improved varieties. Seed transaction data were collected by surveying vine sellers weekly during the 2014 growing season. We combined data from these observed seed transactions with estimated dispersal risk based on village-to-village proximity to create a multilayer network or “supranetwork.” Both the inverse power law function and negative exponential function, common models for dispersal kernels, were evaluated in a sensitivity analysis/uncertainty quantification across a range of parameters chosen to represent spread based on proximity in the landscape. In a set of simulation experiments, we modeled the introduction of a novel pathogen and evaluated the influence of spread parameters on the selection of villages for surveillance and management. We found that the starting position in the network was critical for epidemic progress and final epidemic outcomes, largely driven by node out-degree. The efficacy of node centrality measures was evaluated for utility in identifying villages in the network to manage and limit disease spread. Node degree often performed as well as other, more complicated centrality measures for the networks where village-to-village spread was modeled by the inverse power law, whereas betweenness centrality was often more effective for negative exponential dispersal. This analysis framework can be applied to provide recommendations for a wide variety of seed systems. [Formula: see text] Copyright © 2019 The Author(s). This is an open access article distributed under the CC BY 4.0 International license .

Research conducted in the informal sweetpotato seed (vines) supply system in the Gulu region, northern Uganda (2013Uganda ( -2015 revealed a diverse set of actors using private enterprise in a range of selling and marketing channels. The different channels offer an efficient and effective marketing system, providing different services and conveniences for farmers at different prices. The actors include local vine multipliers, traders, dry season root farmers, transporters and town sellers. The local multipliers and dry season root farmers grow crops during the dry season in swampy areas and sell the vines in the following rainy season to the many farmers who lack access to such areas and therefore lack vines to plant. The presentation and discussion of this case study adds to an expanding argument in the literature for increased attention to support actors in informal food crop sectors who are providing sustainable production and marketing systems on a platform of beneficial and innovative private enterprise. Through their commercial operations, vine multipliers and other actors can effectively meet the demand of customers and at the right time and place. With suitable dissemination programmes installed, these actors could also offer access to new varieties otherwise unavailable to the majority of farmers.

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In many sub-Saharan countries, pig (Susscrofa domesticus) production is increasingly an important food security and income generating activity for smallholder farmers. This is attributed to the high prospects for vigilance of the pork market, driven by urbanisation, population growth and dietary transition towards more animal protein per capita. Therefore, increasing pig production is one of the viable pathways to get smallholder farmers out of poverty and food insecurity. Although there are extensive studies about the elements of pig production, such as feeding, breeding and space requirements; little work has been done on distribution of innovation behaviour and the socio-economic factors that influence labour utilisation in the region. The objective of this study was to determine the socio-economic factors that influence labour (family or hired) utilisation and distribution of innovation behaviour among pig farmers in Northern Uganda. Through a cross sectional survey and descriptive analysis, we characterised smallholder pig farmers in the northern Uganda by type of labour used for pig production, and explored the distribution of the dimensions of innovation behaviour (exploration, experimentation, adaptation and modification) among them. Results revealed that young educated farmers with non-farm employment, a smaller household size, belonging to a farmer group and who had many pigs were more likely to use hired labour than those with counter characteristics. There were significant differences in the number of farmers who exhibited the different dimensions of innovation behavior. Therefore, interventions to boost pig production through the use of hired labour should consider the socio-economic differences among farmers which determine labour constraints they face.