Incidence and ecology of rust disease (Hemileia vastatrix) on wild Coffea arabica in moist Ethiopian mountain forests

Coffea arabica L. (Family Rubiaceae) remains as a backbone of Ethiopian economy and plays an important and significant role in the country’s economy and employment opportunity and accounted for 5 and 25 %, respectively. Ethiopia, the birthplace of Coffea arabica has great coffee genetic diversity in Southwestern part of the country in the Afromontane forests, which will be a potential for identifying wild Coffea arabica resistant to Coffee leaf rust (CLR). A natural population is likely to be the sources of new resistance genes needed to cope with the future evolution in the pathogens of the crop. However, information on the genetic diversity, the incidence and severity of the CLR in moist Ethiopian mountain forests, in south western part of the country is lacking. Hence, identifying wild Coffea arabica genotypes and cultivated genotypes that are resistant against Hemileia vastatrix should gain attention in the world to confront yield and economic losses because of this disease. However, little effort has been done so far to identify wild Coffea arabica genotypes that are resistant against CLR in Ethiopia. Therefore,the aim of the current research is to obtain insight into the genetic diversity, the incidence and severity of coffee leaf rust (Hemileia vastatrix) in Ethiopian forest coffee system and identify the most important environmental drivers responsible for the cause of coffee leaf rust in Ethiopian forest coffee system and to screen the wild Arabica coffee genotypes that are resistant against Hemileia vastatrix. Accordingly, the experiment will be carried out in the moist Ethiopian mountain forest, particularly in Jimma, Oromia Regional State, Southwestern Ethiopia (7°46’N, 36°0’E). The experimental site is located some 350 km away from the capital city of the country Addis Ababa. The specific experimental place will be west of Jimma town some 12 to 35 km away from Jimma town. Two sites (Gera and Mana district) will be selected for this investigation. For this experiment, sites will be selected across the landscape (coffee management gradient) by identifying a number of continuous forests and a number of forest patches in the South western part of the country. Three sites from forest coffee systems where the area experienced no or very little forest management (FC) and three sites from the intensively managed coffee system (semi forest) system located in Gera District will be used. In addition, we will consider altitudes, lowland (Degelu), midland (Genbe) and highland (butter) areas as second experimental sites located within Mana District. The design to be used for this study will be Nested design (where the sampled trees and management will be nested under location/landscape). During data collection, we will establish sampling plot having 20 x 20 m in all sites. Five coffee plants per plot will be randomly selected. Details like incidence and severity, environmental variables and fungal isolates will be collected and analyzed. The laboratory experiment will be conducted to examine the aggressiveness of Hemileia vastatrix isolates collected from different coffee management gradient on wild and cultivated genotypes of Coffea arabica. From this investigation, genetic diversity of coffee leaf rust, incidence and severity, most environmental drivers responsible for cause of coffee leaf rust, aggressiveness of coffee leaf rust isolates collected from different coffee management gradient will be expected to be identified,quantified,determined, and examined, respectively.