Summary: Potato production in East Africa is seriously impacted by the potato cyst nematode (PCN), Globodera rostochiensis, where it has been recorded in at least three countries. In Kenya, it is widespread in all major potato-growing regions, often at very high densities. Consecutive cropping of potato on the same land and a sub-tropical climate have influenced PCN biology. For example, unusually large cysts have been regularly recovered. We have analysed the biological properties of these ‘giant cysts’. The giant cysts contained more eggs than those recovered from UK fields. Egg size did not differ from UK populations and there was no difference in overall lipid content or lipid profile in J2 from giant cysts, compared to control samples. The nematodes in giant cysts were also genetically indistinguishable from any other G. rostochiensis sampled. When grown under UK glasshouse conditions, the offspring of nematodes from giant cysts were no different in size from those grown from control cysts, indicating that gigantism is not a heritable trait and may simply reflect favourable conditions for PCN under Kenyan farming systems. To date, all the PCN tested from Kenya, including those from giant cysts, are avirulent on potato cultivars containing the resistance gene.

Potato (Solanum tuberosum) is a key staple crop in Kenya, where plant-parasitic nematodes are among the most damaging yield constraints for smallholder farmers. This study evaluated fluopyram-treated banana fibre paper, a biodegradable carrier for targeted delivery of ultra-low nematicide doses, under on-farm conditions in Nyandarua County over three consecutive cropping seasons across properly and poorly managed fields. Seventeen nematode genera were identified, with Helicotylenchus and Globodera (potato cyst nematode, PCN) recording the highest population densities. Fluopyram-treated banana paper significantly suppressed Globodera juvenile densities and reduced total nematode reproductive factors by ≥26% and PCN cyst multiplication factors, effects most pronounced under poor management. No significant nematode suppression was observed under good management. Potato yield and quality responded positively to fluopyram treatment: total yield approximately doubled in well-managed plots and increased by ~50% in poorly managed plots relative to untreated controls. Fluopyram-treated plots also produced a higher proportion of large-grade tubers under proper management, improving marketable yield. These findings demonstrate that banana fibre technology can effectively manage nematode pests under variable real-world smallholder conditions, with yield benefits amplified by good agronomic practices. The technology offers a practical, climate-smart and sustainable nematode management tool, with potential for wide adoption across sub-Saharan Africa.

Potato (Solanum tuberosum) is a key staple crop in Kenya, where plant-parasitic nematodes are among the most damaging yield constraints for smallholder farmers. This study evaluated fluopyram-treated banana fibre paper, a biodegradable carrier for targeted delivery of ultra-low nematicide doses, under on-farm conditions in Nyandarua County over three consecutive cropping seasons across properly and poorly managed fields. Seventeen nematode genera were identified, with Helicotylenchus and Globodera (potato cyst nematode, PCN) recording the highest population densities. Fluopyram-treated banana paper significantly suppressed Globodera juvenile densities and reduced total nematode reproductive factors by ≥26% and PCN cyst multiplication factors, the effects most pronounced under poor management. No significant nematode suppression was observed under good management. Total yield in fluopyram treatment approximately doubled in well-managed plots and increased by ~50% in poorly managed plots relative to untreated controls. Fluopyram-treated plots also produced a higher proportion of large-grade tubers under proper management, improving marketable yield. These findings demonstrate that banana fibre technology can effectively manage nematode pests under variable real-world smallholder conditions, with yield benefits amplified by good agronomic practices. The technology offers a practical, climate-smart, and sustainable nematode management tool, with potential for wide adoption across sub-Saharan Africa.