This chapter reviews the status of coffee wilt disease (caused by Gibberella xylarioides), including its occurrence, distribution and importance on arabica coffee in Ethiopia, and highlights some of the factors accelerating the disease and efforts made to contain the problem.

It is essential to reduce coffee yield losses due to coffee wilt disease (CWD) in the country through the development and use of genetically resistant coffee varieties to increase and consistently supply Arabica coffee to the fast growing coffee industry. The soil-borne nature of the pathogen and perennial character of coffee have made management of coffee wilt disease difficult through the conventional control approach of 'uproot and burn infected trees at the spot'. Therefore, longer-term prospects of successful management of coffee wilt disease depend principally upon employing resistant coffee cultivars. With this objective laboratory and field evaluations were conducted to screen some coffee genotypes against coffee wilt disease. Disease severity or mean percent seedling death ranged from 0.00 to 89.96 %. The result showed in lowest seedling death rate, long incubation period and high field survival rate of most accessions indicating resistant reaction to coffee wilt disease. Thus present experiment implied that the potential of obtaining coffee wilt disease resistant coffee variety from these accessions provided that they have other desirable traits like resistance to major coffee diseases, high yield and improved quality.

Coffee wilt disease (CWD) is a serious threat to the food security of small-scale farmers in Ethiopia, causing significant reductions in coffee yield. Currently, there are no effective control measures available against the causative agent of CWD, Fusarium xylarioides. The main objective of this study was therefore to develop, formulate, and evaluate a range of biofungicides against F. xylarioides, derived from Trichoderma species and tested under in vitro, greenhouse, and field conditions. In total, 175 Trichoderma isolates were screened as microbial biocontrol agents against F. xylarioides. The efficacy of two biofungicide formulations, wettable powder and water dispensable granules, were tested on the susceptible Geisha coffee variety in three different agro-ecological zones in southwestern Ethiopia over three years. The greenhouse experiments were set up using a complete block design, while in the field a randomized complete block design was used, with twice yearly applications of biofungicide. The test pathogen spore suspension was applied to the coffee seedlings by soil drenching, and the subsequent incidence and severity of CWD evaluated annually. The mycelial growth inhibition profiles of the Trichoderma isolates against F. xylarioides ranged from 44.5% to 84.8%. In vitro experiments revealed that T. asperelloides AU71, T. asperellum AU131 and T. longibrachiatum AU158 reduced the mycelial growth of F. xylarioides by over 80%. The greenhouse study indicated that wettable powder (WP) of T. asperellum AU131 had the highest biocontrol efficacy (84.3%), followed by T. longibrachiatum AU158 (77.9%) and T. asperelloides AU71 (71.2%); they also had a significant positive impact on plant growth. The pathogen-treated control plants had a disease severity index of 100% across all the field experiments, and of 76.7% in the greenhouse experiments. In comparison to untreated controls, the annual and cumulative disease incidence over the three years of the study period varied from 46.2 to 90%, 51.6 to 84.5%, and 58.2 to 91%, at the Teppi, Gera and Jimma field experimental locations. Overall, the greenhouse and field experiments and in vitro assays support the biocontrol potential of Trichoderma isolates, and T. asperellum AU131 and T. longibrachiatum AU158 in particular are recommended for the management of CWD under field conditions.

Coffee is the most important commodity and source of export earnings in Ethiopian economy which has to fulfills the quality standards of safety up to maximum tolerable level. However, it is naturally associated with several mycoflora and some of them may produce Ochratoxin A unless careful handling measures taken place. Therefore, this research was initiated to assess the status of mycotoxigenic fungi associated with coffee and quantification of Ochratoxin A from locally consumed coffee in Ethiopia. A total of 75 coffee samples were collected from three districts namely, Haru, Homa and Nedjo of West Wollega Zone, Oromia regional state of Ethiopia. Determination of coffee associated mycoflora isolation and identification were conducted at Jimma Agricultural Research Center of plant pathology laboratory while Ochratoxin A detection and quantification were conducted at Ambo Plant Protection Research Center. Malt Extract Agar (MEA) was used for isolation and identification of mycoflora associated with coffee and ELISA kit was used to detect and quantify Ochratoxin A. The result showed that numbers of mycoflora associated with coffee were observed and five of them become the major. Aspergillus niger was the most dominant (73.37%) species detected from most coffee samples, followed by Aspergilus ochraceus (11.30%), Fusarium spp. (7.37%), Penicillium spp. (6.74%), and Rhizopus spp. (1.50%), respectively. Average ochratoxinA recorded was 0 (ND) ppb, 1.24 ppb and 2.02 ppb from Haru, Homa and Nedjo.

Coffee is produced in tropical countries where climatic conditions favor mould growth and development. Moulds are multicellular, filamentous fungi that can grow and produce mycotoxins as secondary metabolites on plants either during pre-harvest or post-harvest, storage, transport, processing, and feeding. Mycotoxins are fungal metabolites and chemical defenses that cause lowered performance, sickness or death in human or animals. Aspergillus, Penicillium and Fusarium species are common and important moulds in the human environment and are among the main agents of spoilage of food and feeds. Problems associated with the occurrence of mycotoxins in coffee have become concern to consumers as well as producers. Several studies have reported Ochratoxin A (OTA) presence in raw coffee. OTA is a form of mycotoxin, produced as a metabolic product of Aspergillus ochraceus, Aspergillus carbonarius and strains of Aspergillus niger. Its presence or absence in any sample is probably related to the length of storage rather than to geographical location or other factors. Most importing countries regulate mycotoxins by setting maximum allowable concentration. The European Union (EU) which are among major buyers of coffee from producing countries set maximum permissible limits for OTA of 5 particles per billion (ppb) in roasted and ground coffee, and 10 ppb in instant coffees. This is a serious indicator for coffee producing and selling countries on how they manage their products. Key factors in the successful management of OTA involve good agricultural practices (GAP) and good manufacturing practices (GMP). As it has great influence on countries economy in general and producers income in particular Strict measures should be taken to improve post-harvest handling and processing of coffee, specially drying of bulk coffee along asphalt roads and bare soils should seriously be discouraged. Research is needed on identification of inexpensive and appropriate sampling and testing protocols of mycotoxins associated with coffee in various coffee agro-ecologies and production systems.