Improved Reverse Transcription Loop-Mediated Isothermal Amplification (RT-LAMP) for the Rapid and Sensitive Detection of Yam mosaic virus.

Yam (Dioscorea spp.) productivity is constrained significantly by the lack of a formal seed system. Vegetative propagation, through tuber setts as 'seed' yams, encourages the recycling of virus-infected planting materials, contributing to high virus incidence and yield losses. Efforts are ongoing to increase the production of high-quality seed yams in a formal seed system to reduce virus-induced yield losses and enhance the crop's productivity and food security. Specific and sensitive diagnostic tests are imperative to prevent the multiplication of virus-infected materials contributing to a sustainable seed yam certification system. During routine indexing of yam accessions, discrepancies were observed between the results obtained from the reverse transcription loop-mediated isothermal amplification (RT-LAMP) test and those from reverse transcription polymerase chain reaction (RT-PCR); RT-LAMP failed to detect Yam mosaic virus (YMV) in some samples that tested positive by RT-PCR. This prompted the design of a new set of LAMP primers, YMV1-OPT primers. These primers detected as little as 0.1 fg/µL of purified RNA obtained from a YMV-infected plant, a sensitivity equivalent to that obtained with RT-PCR. RT-LAMP using YMV1-OPT primers is recommended for all future virus-indexing of seed yams for YMV, offering a rapid, sensitive, and cost-effective approach.

Farmers' knowledge, attitudes and practices towards management of cassava pests and diseases in forest transition and Guinea savannah agro-ecological zones of Ghana.

Background: Cassava is a major staple root crop in Ghana, which serves as a food security and an income generating crop for farming families. In spite of its importance, the crop is plagued with biotic factors such as pests and diseases, resulting in yield and income reductions. Methods: Farmers' knowledge, attitudes and practices towards cassava pest and disease management were investigated. A mixed research questionnaire was used to collect both qualitative and quantitative data from 94 cassava farm households across two major cassava growing agro-ecologies. Results: Using descriptive statistics, parametric and non-parametric analysis, our study revealed that farmers' knowledge on cassava pests was high but low for diseases. Whiteflies ( Bemisia tabaci Gennadius), grasshoppers ( Zonocerus variegatus), aphids ( Aphis gossypii Glover), mealybugs ( Phenacoccus manihoti), termites ( Isoptera), and grasscutters ( Thryonomys swinderianus) were perceived as the most common damaging pests. Farmers' descriptions showed that disease pathogens attacked foliar tissues, stem and root tissues and caused leaf dropping and die back. Cassava mosaic disease and root rot were the most common diseases; however, disease descriptions suggested the incidence of viral, bacterial and fungal diseases. Some of the farmers observed mixed symptoms on their farms. The results also showed that only 25.5% cultivated improved varieties. Management actions applied included field sanitation practices and pesticide application. The effectiveness level of the control actions was rated moderately effective. Conclusions: The analysis showed heterogeneity in personal and farm level characteristics of respondents across the two agro-ecologies, but agro-ecologies were independent of the management practices employed. There is a need to improve farmers' access to improved disease-free planting materials through efficient dissemination pathways and increase farmers' knowledge on cassava pests, diseases and integrated management through publfic awareness creation and capacity building by extension agents and research institutions. Continued government investment is needed to achieve sustainable outcomes.