Nerine peach. © INRA, MONET René

Pathogen-related harvest losses: analysis and quantification

Coffee pests: evaluating losses to compare cropping systems

In the context of the CoLosses project, Clémentine Allinne and her team have modelled the yield losses of coffee due to diseases and pests in Costa Rica. The purpose of their model is to evaluate the impact of reducing the use of plant health products and of diversifying the agro-ecosystems studied.

Updated on 09/12/2016
Published on 01/12/2016

. © INRA, MAITRE Christophe
© INRA, MAITRE Christophe

The CoLosses project (Coffee yield Losses) is based on a tropical agroecological model which Clémentine Allinne summarises as follows: “The intensive management of plantations implies a considerable use of plant health products which generate high yields (despite a loss of intrinsic qualities) and above all a high environmental cost.  If, on the contrary, an agroecological management system is introduced that uses few pesticides by diversifying the systems, the losses may be greater but production costs will be lower and quality better, and the crop becomes more economically viable: this offers another option for producers.  The CoLosses project aims to supply tools to compare these two types of management.”

 A reliable indicator of losses: the number of dead branches

Coffee fruits develop on the previous year's stems.  Harvest losses due to disease and pests may therefore be primary (reducing yield in the current year) or secondary (affecting yield the next year).  The initial results obtained have been able to estimate primary losses at 43% and secondary losses at 37%.

“We measured six parameters, such as the number of fruiting nodes and the degree of foliage damage by diseases and pests.  One of these parameters, the number of dead branches, proved to be a reliable indicator of both primary and secondary losses.”  The yield estimation model was thus based on these measurements.  “Just three variables (number of fruiting nodes, fruits per node and the maximum of dead branches per plant) were sufficient to estimate the actual yield.  The achievable yield (without losses) was estimated by eliminating the “dead branches” variable.  The losses were calculated from the difference between the achievable and actual yields, related to the achievable yield.”

Agroecological adaptations

Another action by CoLosses, carried out in the context of the CASCADE project, was able to identify and evaluate the cultivation practices based on the resources and functioning of ecosystems (EbA, for Ecosystem-based Adaptation), necessary to adapt to climate change.  These practices are fundamental in the context of small farms, which are very numerous in Central America.

The CoLosses project

CoLosses is similar to two other projects implemented under the DAMAGE action: ModQual (modelling of quality losses) and QMPV (harvest losses due to vine pests and diseases). Indeed, these three projects all concern perennial plants (coffee, vine, temperate and tropical fruit trees); they model harvest sizes and also crop quality criteria, and in the longer term should integrate economic parameters.

Partners: CATIE, Conservation International (CASCADE project: Ecosystem-based Adaptations for Smallholders Subsistence and Coffee Farming Communities in Central America).