Etude comparée de l'agressivité de races physiologiques d'Hemileia vastatrix Berk et Br. possédant diverses charges en genes de virulence :

In addition to specific (vertical) resistance of Coffea arabica to coffee rust (Hemileia vastatrix Berk and Br); there is another form of resistance of the quantitative type (incomplete or horizontal resistance) which has been found, in particular, in individuals in group E. This resistance appears clearly in the field on coffee plants from Ethiopia collected during the ORSTOM/IRCC survey in 1966. The aim of the studies at present being carried out in the IRCC plant pathology laboratory in Montpellier is to analyze the non-specific character of this resistance by studying, at the same time, the plants reactions to artificial inoculations with different physiological strains of the parasite (I, II, III, XV and X). This work has made it possible to assess the aggressiveness of the strains that have 1, 2 or 3 genes of virulence. The method used consists of artificial inoculation of whole leaves that have been removed from the plant and are kept alive in a humid chamber. The Caturra cultivar was regularly chosen as a very susceptible check. After daily observation of the symptoms for about forty days, a statistical study was made of the development of the susceptibility criteria selected and study was also undertaken with an optical microscope. The results confirm that some Arabica have incomplete resistance to strain II. For the other 2-gene (I, III and XV) 0r 3-gene (X) strains, two main remarks can be made: - classification according to the scale of susceptibility of the tested cultivars is the same as with strain II, but the maximum index of intensity of the disease is, in every case, lower; - the symptoms develop much more slowly than with strain II. These different results show the non-specific character of the incomplete resistance observed on the coffee plants in group E. These results need to be confirmed on whole plants and tested in the field before any plans are made to utilize this source of resistance

Bibliographic Details

Main Authors:	71666 Gil Fagioli, S., 48566 Berry, D., 48945 Bieysse, D., 97351 Muller, R.A., 3180 Association Scientifique Internationale du Café, París (Francia), 32077 12. International Scientific Colloquium on Coffee Montreal (Canadá) 29 Jun - 3 Jul 1987
Format:	biblioteca
Language:	eng
Published:	París (Francia) 1988
Subjects:	COFFEA ARABICA, HEMILEIA VASTATRIX, ROYA, ENFERMEDADES FUNGOSAS, RAZAS FISIOLOGICAS, VIRULENCIA, INOCULACION, CATURRA,
Online Access:	http://orton.catie.ac.cr/repdoc/
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