Status of Forest Coffee (Coffea arabica L.) Diseases in the Afromontane Rainforest Areas of Ethiopia: A review

Ethiopia, as the center of origin for Coffea arabica, hosts a large diversity of germplasm. Besides drastic reduction in the forest cover and low average yield, the crop is attacked by several diseases, among that coffee leaf rust; coffee berry disease and coffee wilt disease are the major fungal diseases contributing to reduced yield in the country. In this article, the main objective is to provide an overview on current status of major forest coffee diseases prevalence and distributions recorded in afromontane rain forest area of Ethiopia; and to indicate the incidence and severity of forest coffee diseases in the forest coffee populations and elucidates some basic management studies and efforts made to manage those diseases occurred over the past 10 years. The incidences of diseases are reviewed based on different research out puts that was conducted in the afromontane rainforests of the southeast (Harenna) and southwest (Bonga, Berhane-Kontir, Yayu) of Ethiopia. CLR incidences in Ethiopia were present in all forest coffee areas with highest between January and March and lows between June and October with incidence varied from 0.36 to 18.5% in Bonga, 1.8 to 49% in Berhane-Kontir, and 11.8 to 62.6% in Yayu forest coffee populations. The corresponding severity ranged from 0.08 - 1.2%, 0.24 - 1.7% and 0.91 - 3.3% whereas the Sporulation Lesion density varied from 0.08 - 1.9, 0.33 - 3.65 and 1.5 - 5.9% in that order. Leaf rust was low (18.5%) in July 2007 and high (62.6%) in January 2008. CBD was present mostly in Bonga (40.0%) and Yayu (26.3%), but less frequent in Harenna (18.6%) and Berhane-Kontir (6.0%). CWD as a recently developed disease in Arabica coffee could be detected ranging from during the dry season of 2012, the incidence ranged respectively from 0 to 15.4%, 7.3 to 37.6%, 0 to 22.3%, and 26.4 to 28.3% in Bonga, Berhane-Kontir, Yayu and Harenna. During the wet season of 2012, the average disease incidence was 11.9, 29.2, 13.2 and 27.7% at the respective forest sites. Significant variation also observed among each coffee tree within a location and season significantly interacted with both location and coffee trees within a location. As researcher indicated in 2010 heterogeneity of forest coffee populations to those diseases in the field under native agro-ecology provides an opportunity to develop resistant varieties among the enormous forest coffee genetic resources and at the same time calls for strategic multi-site in situ conservation to rescue and maintain the present genetic variation and enhance co-evolutionary processes. From this review, in the case of CBD and CWD selections of tolerant Arabica accessions are being pursued from local landraces in afromountan rain forest areas of Ethiopia that undoubtedly needs detailed research work on screening tolerant variety against to the major diseases