Environmental factors associated with disease incidence in plant species from a Mexican seasonal tropical dry forest

Occurrence of plant pathogens and levels of disease are modified by variations in the abiotic and biotic environment. However, there is little information on the effects of environmental changes at a local scale on incidence and severity of foliar disease in seasonal tropical natural systems. We studied the occurrence of leaf fungal diseases in four tree species from a Mexican seasonal tropical dry forest over 2 yr and explored its relation with abiotic factors. Necrotic leaf spots affected all plant species. The probability of disease incidence tended to be higher in the year 2008 than in 2007, and varied among surveyed sites. Mean proportion of leaf area damaged per plant varied among sites. In all the cases where the relationship was significant, the probability of disease incidence and leaf area damaged per plant were negatively affected by canopy openness and mean maximum temperature. Only in Achatocarpus gracilis was the probability of disease incidence positively affected by relative humidity in both years, and the leaf area damaged per plant was only positively affected by this variable in 2007. Our study contributes to the understanding of the role of abiotic factors in the occurrence and severity of diseases in seasonal tropical dry forests.