Climate Change in the High Andes:implications and adaptation strategies for small-scale farmers

Abstract: Global climate change represents a major threat to sustainable farming in the Andes. Farmers have used local ecological knowledge and intricate production systems to cope, adapt and reorganize to meet climate uncertainty and risk, which have always been a fact of life. Those traditional systems are generally highly resilient, but the predicted effects, rates and variability of climate change may push them beyond their range of adaptability. This article examines the extent of actual and potential impacts of climate variability and change on small-scale farmers in the highland Andes of Bolivia, Ecuador and Peru. It describes how climate change impacts agriculture through deglaciation, changes in hydrology, soil and pest and disease populations. The article highlights some promising adaptive strategies currently in use by or possible for producers, rural communities and local institutions to mitigate climate change effects while preserving the livelihoods and environmental and social sustainability of the regio

Seed degeneration in potato : the need for an integrated seed health strategy to mitigate the problem in developing countries

Seed potato degeneration, the reduction in yield or quality caused by an accumulation of pathogens and pests in planting material due to successive cycles of vegetative propagation, has been a long-standing production challenge for potato growers around the world. In developed countries this problem has been overcome by general access to and frequent use of seed, produced by specialized growers, that has been certified to have pathogen and pest incidence below established thresholds, often referred to as certified seed. The success of certified seed in developed countries has concentrated the research and development agenda on the establishment of similar systems in developing countries. Despite these efforts, certified seed has had little penetration into the informal seed systems currently in place in most developing countries. Small-scale farmers in these countries continue to plant seed tubers acquired through the informal seed system, i.e. produced on-farm or acquired from neighbours or local markets. Informal seed tubers frequently have poor health status, leading to significant reductions in yield and/or market value. This review emphasizes the need to refocus management efforts in developing countries on improving the health status of seed tubers in the informal system by integrating disease resistance and on-farm management tools with strategic seed replacement. This 'integrated seed health strategy' can also prolong the good health status of plants derived from certified seed, which would otherwise be diminished due to potential rapid infection from neighbouring fields. Knowledge gaps, development challenges and impacts of this integrated seed health strategy are discussed.PostprintPeer reviewe

Risk assessment for epidemic spread of the quarantined potato pathogen Synchytrium endobioticum in the Republic of Georgia

Synchytrium endobioticum (causal agent of potato wart) is a devastating soilborne pathogen. Eradication is difficult and infestation can result in 100% yield loss, making this a strictly quarantined pathogen worldwide. Emerging epidemics pose a high risk to production in Georgia where potato is an essential staple, grown primarily by smallholder farmers, and yields are among the world’s lowest. S. endobioticum was first reported in Georgia in 2014 in a localized outbreak in Adjara. Because pathogen dissemination is primarily via human transport of infested tubers, understanding the local potato seed system is critical. This study was the first to systematically characterize the actors involved in seed and ware potato production and trade in Georgia. To collect this information, an expert elicitation was conducted in 2017 across a broad range of participants from the Georgian potato production sector. We present a model of the current potato seed exchange network for the most important agroecological regions. We integrated network analysis in a risk assessment for S. endobioticum spread in Georgia under 1) no intervention, 2) quarantine, 3) introduction of host plant resistance, and 4) combined quarantine and resistance deployment. Preliminary analyses suggest that under no intervention, risk of spread is high, while rapid and consistent quarantine can be effective. Methods presented here provide a general framework for future seed system risk assessments

User guide to the toolbox for working with root, tuber and banana seed systems. RTB User guide

This user guide to the Toolbox for working with root, tuber and banana seed systems introduces tools to diagnose, evaluate, and improve seed systems of banana, cassava, potato, sweetpotato, and yam. As a whole, these crops are called roots, tubers and bananas, and they are crucial for food security and income generation, especially in developing countries. All of these crops are reproduced vegetatively, from roots, tubers, stems, suckers or vines. This bulky planting material is expensive to transport. Vegetative seed is perishable and (except for potatoes, yams and a few other exceptions) must be planted as fresh as possible, and it is more likely to carry pests and diseases than true seed. Besides these unique challenges, improved seed systems of root, tuber and banana crops give farmers the opportunity to boost their livelihoods by accessing better quality planting material from landraces or improved varieties that are high yielding, resistant to stresses, more nutritious or more responsive to consumer demand

Virus infection and grazing exert counteracting influences on survivorship of native bunchgrass seedlings competing with invasive exotics

1.  Invasive annual grasses introduced by European settlers have largely displaced native grassland vegetation in California and now form dense stands that constrain the establishment of native perennial bunchgrass seedlings. Bunchgrass seedlings face additional pressures from both livestock grazing and barley and cereal yellow dwarf viruses (B/CYDVs), which infect both young and established grasses throughout the state. 2.  Previous work suggested that B/CYDVs could mediate apparent competition between invasive exotic grasses and native bunchgrasses in California. 3.  To investigate the potential significance of virus-mediated mortality for early survivorship of bunchgrass seedlings, we compared the separate and combined effects of virus infection, competition and simulated grazing in a field experiment. We infected two species of young bunchgrasses that show different sensitivity to B/CYDV infection, subjected them to competition with three different densities of exotic annuals crossed with two clipping treatments, and monitored their growth and first-year survivorship. 4.  Although virus infection alone did not reduce first-year survivorship, it halved the survivorship of bunchgrasses competing with exotics. Within an environment in which competition strongly reduces seedling survivorship (as in natural grasslands), virus infection therefore has the power to cause additional seedling mortality and alter patterns of establishment. 5.  Surprisingly, clipping did not reduce bunchgrass survivorship further, but rather doubled it and disproportionately increased survivorship of infected bunchgrasses. 6.  Together with previous work, these findings show that B/CYDVs can be potentially powerful elements influencing species interactions in natural grasslands. 7.  More generally, our findings demonstrate the potential significance of multitrophic interactions in virus ecology. Although sometimes treated collectively as plant ‘predators’, viruses and herbivores may exert influences that are distinctly different, even counteracting