Landscape context and scale differentially impact coffee leaf rust, coffee berry borer, and coffee root-knot nematodes. Avelino, Romero-Gurdian, Cruz-Cuellar, and DeClerk. 2012. Ecological Applications.
In ecology, context is important. Ecosystems are comprised of many interdependent organisms, and those interactions are influenced by the environment at different scales. In the case of coffee pests, that can mean the conditions on an individual coffee plant, in a particular patch of coffee, or on one or many neighboring farms. This study looked at how the surrounding landscape — up to 1500 m around coffee plots — impacted the incidence of several coffee pests.
The authors looked at 29 small plots of coffee within larger plantings in Costa Rica. They wanted to see how different land use practices at different scales might influence coffee leaf rust (Hemileia vastatrix), the coffee berry borer (Hypothenemus hampei), and root-knot nematodes (in the genus Meloidogyne).
Populations of the virtually immobile root-knot nematodes did not appear to be correlated with landscape. Not surprisingly, coffee plots embedded in a landscape with a high proportion of other coffee plots facilitated the movement and spread of coffee berry borers.
I found the response of coffee leaf rust to be the most interesting: there were increased epidemics of coffee leaf rust in areas where coffee plots were in a landscape that had open uses such as pasture. The rust spores are spread by wind. The air turbulence produced by gaps of pasture among plots of coffee promoted the release of the rust spores which then dispersed in the landscape. When the wind turbulence released clusters of spores, they did not travel as far and resulted in locally intense outbreaks of rust.
The landscape-scale effects on the rust and borer varied depending on the distance of the plots from the various landscape features, and also fluctuated during the season, so the effects of landscape are not simple; these are outlined in the paper. However, the results suggest that growing coffee in plots that are separated from others by native forest could hinder the spread of both the borer and the rust, as well as act as reserves and corridors for other biodiversity.
Avelino, J., Romero-Gurdián, A., Cruz-Cuellar, H., & Declerck, F. (2012). Landscape context and scale differentially impact coffee leaf rust, coffee berry borer, and coffee root-knot nematodes Ecological Applications, 22 (2), 584-596 DOI: 10.1890/11-0869.1