Shade over coffee: its effects on berry borer, leaf rust and spontaneous herbs in Chiapas, Mexico

The objective of this research was to determine the relationships between different ecological features of shade and the incidence of coffee berry borer, coffee leaf rust and spontaneous herbs in rustic coffee plantations in Chiapas, Mexico. Thirty-six 10 m by 10 m plots were established within coffee plantations. The following variables were measured or estimated: number of vegetation strata, percent canopy cover, direct, diffuse and total sunlight below the canopy, plant species richness and diversity, shade tree/shrub density, altitude, aspect, basal area, yields, percentage of coffee berry borer (Hypothenemus hampei Ferr), percentage of coffee leaf rust (Hemileia vastatrix Berk & Br.),percentage of spontaneous herb cover and the presence of paths and runoffs.Results showed a complex agroforestry system, composed of five strata. Coffee berry borer and coffee leaf rust incidence averages were 1.5% and 10.1%,respectively. Average spontaneous herb cover was 34.1%. Coffee leaf rust percentage correlated positively with the coffee berry borer. Number of strata of shade vegetation correlated negatively with leaf rust, while the presence of paths correlated positively with the leaf rust. Species richness and diversity correlated negatively to broad-leaf-herb cover and the presence of runoffs correlated positively to this last variable. Shade tree density (> 10cm d.b.h.) correlated negatively to linear-leaf-herb cover. Percentage of shade cover, light, coffee density, aspect, stand age, basal area and yields were not correlated to pest, disease and weeds. Results support the ecological theory that postulates that diversity and structural complexity in mixed plant systems maintain a healthy system.This revised version was published online in November 2005 with corrections to the Cover Date.