Monitoring Spore Dispersal and Early Infections of Diplocarpon coronariae Causing Apple Blotch Using Spore Traps and a New qPCR Method

Apple blotch (AB) is a major disease of apple in Asia and recently emerged in Europe and the United States. It is caused by the fungus Diplocarpon coronariae (formerly Marssonina coronaria; teleomorph: Diplocarpon mali) and leads to severe defoliation of apple trees in late summer, resulting in reduced yield and fruit quality. To develop effective disease management strategies, a sound knowledge of the pathogen's biology is crucial. Data on the early phase of disease development are scarce: No data on spore dispersal in Europe are available. We developed a highly sensitive TaqMan qPCR method to quantify D. coronariae conidia in spore trap samples. We monitored temporal and spatial dispersal of conidia of D. coronariae and the progress of AB in spring and early summer in an extensively managed apple orchard in Switzerland in 2019 and 2020. Our results show that D. coronariae overwinters in leaf litter, and spore dispersal and primary infections occur in late April and early May. We provide the first results describing early-season dispersal of conidia of D. coronariae, which, combined with the observed disease progress, helps to understand the disease dynamics and will be a basis for improved disease forecast models. Using the new qPCR method, we detected D. coronariae in buds, on bark, and on fruit mummies, suggesting that several apple tissues might serve as overwintering habitats for the fungus, in addition to fallen leaves. [Formula: see text] Copyright © 2023 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

Digital Technology and Services for Sustainable Agriculture in Tanzania: A Literature Review

Digital technology has the potential to eradicate extreme poverty and food insecurity to the majority of smallholder farmers in the world. This paper aims to identify knowledge gaps on digital technology for sustainable agriculture and assess their availability to smallholder farmers worldwide. The particular case of Tanzania receives special attention. We conducted an extensive literature search from relevant databases for review. The advanced digital technology in agriculture, mostly used by large scale farmers, significantly contributes to sustainable agriculture. However, the existing digital services for smallholder farmers lack sustainability in the agriculture context and hardly meet the needs for a comprehensive set of services in a complete farming cycle. In most developing countries, Tanzania case included, digital technology and services respond to a challenge at a particular stage of the farming process or to a specific value chain. Based on this literature review, we identify inequalities among large and small farmers, as well as environmental challenges caused by ICT itself. To conclude we provide suggestions for improvements for smallholder farmers: developing a digital platform that addresses smallholder farmers’ challenges in a complete farming cycle, bringing together the stakeholders at a country level, in order to achieve sustainable agriculture and support adoption of cutting-edge digital technology. These suggestions will be the starting point for future research.