Shade Effects on the Dispersal of Airborne Hemileia vastatrix Uredospores

Abstract

Hemileia vastatrix caused a severe epidemic in Central America in 2012-13. The gradual development of that epidemic on nearly a continental scale suggests that dispersal at different scales played a significant role. Shade has been proposed as a way of reducing uredospore dispersal. The effect of shade (two strata: Erythrina poeppigiana below and Chloroleucon eurycyclum above) and full sun on H. vastatrix dispersal was studied with Burkard traps in relation to meteorological records. Annual and daily patterns of dispersal were observed, with peaks of uredospore capture obtained during wet seasons and in the early afternoon. A maximum of 464 uredospores in 1 day (in 14.4 m(3) of air) was recorded in October 2014. Interactions between shade/full sun and meteorological conditions were found. Rainfall, possibly intercepted by tree cover and redistributed by raindrops of higher kinetic energy, was the main driver of uredospore dispersal under shade. Wind gusts reversed this effect, probably by inhibiting water accumulation on leaves. Wind gusts also promoted dispersal under dry conditions in full sun, whereas they had no effect under shaded conditions, probably because the canopy blocked the wind. Our results indicate the importance of managing shade cover differentially in rainy versus dry periods to control the dispersal of airborne H. vastatrix uredospores.

The coffee leaf rust pathogen Hemileia vastatrix: one and a half centuries around the tropics

“…Secondary losses, arising from low yield as a result of reduced vegetative growth caused by the previous epidemic, tend to be more important than primary losses (Avelino et al ., ). Modelling of rust epidemics according to agroecological variables has revealed the relevance of local agronomic factors, including shade, canopy density and soil fertility, interacting with regional environmental factors, such as rainfall (Avelino et al ., ; Boudrot et al ., ). At the global level, climate change scenarios have also been analysed in the context of CLR, with shorter incubation periods being forecasted (Ghini et al ., ) and disease‐favouring scenarios mapped (Alves et al ., ).…”

“…At the global level, climate change scenarios have also been analysed in the context of CLR, with shorter incubation periods being forecasted (Ghini et al ., ) and disease‐favouring scenarios mapped (Alves et al ., ). Indeed, this disease has been increasingly reported at higher altitudes in recent years (Boudrot et al ., ; Rozo et al ., ).…”

Interactive effects of altitude, microclimate and shading system on coffee leaf rust

“…Since shading effects vary across sites and season, its impacts on coffee pests and diseases are ambiguous (Avelino et al 2006(Avelino et al , 2011López-Bravo et al 2012;Boudrot et al 2016). Few studies were conducted across different temporal and spatial scales or focused on the effect of multiple factors and response variables.…”

Learning from social–ecological crisis for legal resilience building: multi-scale dynamics in the coffee rust epidemic

“…In a quest to increase productivity, public and private actors have promoted production intensification and shade management, with recommendations for coffee fields to have lower tree-cover density (Perfecto et al 1996). Although the effects of shade on coffee rust are complicated and antagonistic-for example, more shade limits wind circulation, thus restricting spore dissemination (Boudrot et al 2016;López-Bravo et al 2012), yet shade can also function as a temperature buffer, maintaining ideal conditions for fungal reproduction by limiting high and low temperature peaks (López-Bravo et al 2012)-producers in the Chiapas Sierra Madre mention that government institutes, coffee companies, and technicians recommended they reduce shade cover to address this fungal epidemic. This has led to the transformation of coffee systems from dense shade towards less shade (i.e.…”