Indigenous Management Practices to Reduce Pests and Pathogens of Cash Crops in Agroforestry Systems

Indigenous farming practices (e.g., traditional agroforestry) can sustain high levels of biodiversity and ecosystem services (e.g., natural pest and pathogen control) and can be sustainable in the long term, especially if integrated with innovation and technology. We investigate the factors influencing pests and pathogen impact on agroforestry practices in Indigenous communities in Bali, Indonesia. We collected data via 100 plots with different compositions of crops in both community forests (where the use of agrochemicals is precluded by social rules) and polyculture (with no limitation on the use of agrochemicals). For each plot, we obtained a score of infestation for four cash crops (banana, coffee, cacao, and vanilla) by calculating the proportion of plants affected and giving a percentage score of infestation. Analysis was performed via generalised additive models with crop richness, canopy cover, and agroforestry type as factors. The crop with highest damage was cocoa (63.9% plants affected by black pod disease) and we also recorded a widespread incidence of the vascular streak dieback (19.4% plants affected). Fusarium stem rot was the second highest damage in crops, with 30.0% of vanilla plants infected. Fusarium wilt affected 10.2% of banana plants and the coffee berry borer affected 9.7% of coffee plants. There were no differences in pest and pathogen incidence between community forest and polyculture, thus insecticides and fungicides had little to no impact on crop infestations. An increased crop richness favoured a reduction in some insect pests, suggesting a potential increase in natural pest control. Since insecticides and fungicides do not seem to have a significant impact in reducing pest and pathogen infestation (probably due to genetic variability and resistance of pests and pathogens), the most effective Indigenous practice is to diversify profits from different crops, thus buffering the negative effects of market fluctuations and yield loss.