Publications des agents du Cirad


Shade effects on coffee rust (Hemileia vastatrix)

Avelino J., Badaroux J., Boudrot A., Brenes Loaiza M.A., Granados E., Henrion M., Lopez D., Merle I., Pico Rosado J.T., Segura B., Vilchez Mendoza S.J., Smith M., De Melo E.. 2019. In : Dupraz Christian (ed.), Gosme Marie (ed.), Lawson Gerry (ed.). 4th World Congress on Agroforestry. Book of abstracts. Montpellier : CIRAD; INRA, p. 789. World Congress on Agroforestry. 4, 2019-05-20/2019-05-22, Montpellier (France).

To better understand shade effects on coffee rust (Hemileiavastatrix), we studied pathogen dispersal, deposition, germination, penetration, colonization and sporulation under shade and full sun conditions (Figure). Studies were conducted from 2008 in the CATIE agroforestry system long term trial, at Turrialba, Costa Rica, at 600 m of altitude. Shade had a preponderant and unwished effect on spore conservation during rains. At full sun, spores were washed from the leaves to the ground more easily. An average loss of 69 spores cm-2 of ground, at full sun, was estimated after a rainy day, under coffee trees, while under shade, only 52 spores cm-2 were lost, despite inoculum stock being on average about 25 638 spores per coffee tree branch at full sun and 63 579 spores under shade. The reduc-tion of the inoculum stock by rains was therefore 3.3 times higher at full sun as compared to shade. This can be explained by the interception of rainwater by shade trees. As lost spores cannot contribute to the growth of the epidemic, this effect seems to be one of the most relevant effects favoring rust under shade.Shade is necessary to cope with climate change in coffee systems. Many of the negative effects of shade have to do with the interception of rainwater (reduced throughfall water and also higher raindrop kinetic energy). Shade tree functional traits or management systems that allow to increase throughfall water in coffee plots would be of great interest to manage rust.

Mots-clés : coffea; agroforesterie; arbre d'ombrage; absorption d'eau; adaptation aux changements climatiques; maladie des plantes

Documents associés

Communication de congrès

Agents Cirad, auteurs de cette publication :