Citrus phaeoramulariosis due to Phaeoramularia angolensis in Cameroon: parasitic expression at different altitudes

摘要

Introduction. Citrus leaf and fruit spot due to P. angolensis represents a serious production constraint in tropical Africa. Disease expression may vary greatly from one location to another. Materials and methods. Disease development was studied onyoung seedlings of grapefruit cv. Marsh inoculated with a conidia suspension and transferred to eight locations at (80 to 1250) m elevation. Temperature (T) and relative humidity (RH) were recorded on the sites during the study. Results and discussion. Disease incidence increased with altitude. The Nyombe Station (80 m elevation, Taverage > 25degC with Tmax above 30degC and RHaverage < 80%, with RHmin often below 60%) was far less conducive to disease development than the rest of the locations, which experienced cooler and more humid climatic conditions (Tmin < 20 degC and RHmin > 60%). Conclusion. This study provides preliminary information on characterization of regions that may be invaded by P. angolensis. The study should be pursued, including differentecological situations, to enable the mapping of the risk of this threat.