Small, rural farmers often produce on marginal land with steep slopes and poor soil quality, yet they can grow a large portion of the world’s food. In recent years, small avocado producers in post-conflict coastal Colombia have returned to their farms after decades of war to discover they must battle the plant pathogen Phytophthora cinnamomi devastating their trees. While this disease has been well described in the US and elsewhere, no previous research has examined Phytophthora cinnamomi in avocado production in this diverse tropical agroecosystem. The purpose of this research was to identify relationships among environmental conditions and Phytophthora cinnamomi on the ground in remote smallholder farms in the coastal mountains of Colombia. Using in-field bioassays and symptom observations, disease incidence and predictor variables were measured for 72 trees across 12 farms representing 3,600 km2 of territory.
Results/Conclusions
Although the disease proved to be ubiquitous in the region, contrary to reported trends from high-input avocado research, soil compaction and increasing slope were both negatively related to disease incidence at the farm level. Results suggest that, given unpredictable and disease-prone agroecosystems, small farmers in this remote region must be supported in retaining their highly diversified cropping palettes, but the steep and rocky growing terrain may provide a refuge from the heavy disease burden of the tropical rainforest climate and soils. The holistic approach these small farmers utilize may be essential to the sustainability of their agroecosystems.