S21 - Session O3 - Tools for the management of the banana bunchy top disease in small holder systems

Authors: Bonaventure Omondi Aman Oduor *, Misheck Soko, Innocent Nduwimana, Alice Simbare, Geoffroy Dato, Celestin Niyongere, Charles Staver, Faride Athindehou

The removal of infected individuals is a common practice for minimizing local transmissionin in the management of plant diseases outbreaks. This requires robust early detection and efficient roguing at landscape scale. We studied the effectiveness of long-term roguing in managing BBTD infections in smallholder farming systems in Africa. We then investigated BBTD presentation and infectiousness in four varieties of banana; and modelled the cost implication of these results under various production systems spread over four countries. Roguing led to a reduction of BBTD incidence to less than 5% over three years. All non-managed fields collapsed within 3 years. New infections were lower in rogued than non-managed farms though farms followed a seasonal cycle. Positive selection of seed from managed fields resulted in seed of a much lower prevalence (below 2%), for local planting. BBTD symptoms were dependent on cultivar and, potentially, season related crop stress, presenting a seed systems risk for some varieties. Over 90% of farmers clearly understood BBTD at the later symptom stages but not at the early stage which is useful in roguing practice. Also, early symptoms were generally not prioritized in crop management. Roguing is context specific relying on identification, prioritization, frequency and adherence to prompt and efficient disposal of infected plants. The motivating labour investment into frequent management would contribute to recovery and decreased risk of disease at landscape scale. Tools now exist to facilitate disease detection, knowledge and organization of disease management. We continue to study the optimum intensity and economic thresholds of roguing under different disease and production conditions.