Ethiopia mainly uses resistant varieties and cultural disease management strategies to tackle thi... more Ethiopia mainly uses resistant varieties and cultural disease management strategies to tackle this disease. However, still there is a lack of improved and resistant varieties in coffee growing areas of the country including Arsi Zone. The objectives of this study were to investigate the resistance of Arsi coffee collections to Coffee Berry Disease through arti cial inoculation of green berries on mother trees, and younger coffee seedlings under controlled conditions. The eld experiment was conducted at Gololcha (Arbagugu state farm) and Mechara Agricultural research center on station. A hypocotyl test was conducted at Jimma Agricultural research center. Field test was carried out on 13 Arsi coffee collections and the Coffee Berry Disease -susceptible Arusa coffee variety. Standard checks like susceptible variety (370) and resistant varieties 741 and 754 were used for hypocotyl tests. Seventeen treatments were used for hypocotyl tests. Result showed the presence of a signi cant difference in Coffee Berry Disease reaction levels among genotypes (P < 0.001) under eld conditions. The infection percentage of berries varied from 2.89 to 25.93% at Gololcha (Arbagugu state farm) and 3.25 to 34.92% at Mechara three weeks after treatment applications. According to the results, the resistant variety 741 showed the lowest infection percentage (15.04%) in comparison to all other collections and/or varieties at the seedling stage. Therefore, coffee collections that showed the lowest level of infection percentage under both experimental conditions (Ar15/11, Ar05/11, and Ar70/11) were recommended for further breeding strategies to develop resistant coffee varieties against the disease.
Citrus canker: a new disease of Mexican lime (Citrus aurantifolia) and sour orange (C. aurantium)... more Citrus canker: a new disease of Mexican lime (Citrus aurantifolia) and sour orange (C. aurantium) in Ethiopia. Abstract-Introduction. Citrus canker, caused by the bacterium Xanthomonas axonopodis pv. citri, is a serious disease of most commercial citrus cultivars and some citrus relatives. Surveys were conducted in small-scale farms, commercial plantations, backyard orchards and nurseries in order to quantitatively study the occurrence and distribution of the disease and determine the intensity and field host range. Materials and methods. Seventeen locations in four regional states of Ethiopia were surveyed. Incidence on leaves was determined by counting total number of leaves and expressed as a proportion of leaves with at least one lesion. Incidence on fruits was determined on attached fruits, recorded as presence or absence of the symptoms. Severity was also measured on leaves and fruits. The identity of the pathogen was confirmed by morphological, biochemical and physiological characterization and detached leaf tests of representative isolates. Results. The surveys indicated the occurrence of citrus canker in Ethiopia. Overall incidence on leaves was 71.4% of leaves with at least one lesion and severity was 26.8% of leaf area infected. Incidence on fruits was 30% of fruits infected and severity was 21.25% fruit area infected. Morphological, biochemical and physiological characterization and detached leaf tests of isolates indicated characteristics similar to X. axonopodis pv. citri. The host range for citrus canker in Ethiopia was limited to Mexican lime (C. aurantifolia) and sour orange (C. aurantium). Based on the field host range and detached leaf tests, it appears that the X. axonopodis pv. citri variant that occurs in Ethiopia has similar host ranges to that of atypical Asiatic (Xac-A*) form. Canker severity significantly correlated with temperature but not with rainfall, elevation or tree age. Conclusion. This is the first confirmed report of the disease in Ethiopia. Ethiopia / Citrus aurantium / Citrus aurantiifolia / Xanthomonas / plant diseases / pathogens / identification / geographical distribution / host plants Le chancre citrique : une nouvelle maladie de la lime mexicaine (Citrus aurantifolia) et de l'orange amère (C. aurantium) en Éthiopie. Résumé-Introduction. Le chancre citrique, provoqué par la bactérie Xanthomonas axonopodis pv. citri, est une maladie sérieuse de la plupart des cultivars commerciaux d'agrumes et d'autres genres voisins. Des prospections ont été conduites en exploitations de petite taille, en plantations commerciales, en vergers de case et en pépinières afin d'étudier quantitativement l'occurrence et la distribution de la maladie et d'en déterminer l'intensité et les hôtes. Matériel et méthodes. Dix-sept lieux répartis dans quatre États d'Éthiopie ont été visités. L'incidence sur feuilles a été exprimée par la proportion de feuilles portant au moins une lésion parmi l'ensemble des feuilles échantillonnées. L'incidence sur fruits a été déterminée sur les fruits sur arbre, en notant la présence ou l'absence des symptômes. La sévérité a été également mesurée sur feuilles et fruits. L'identité du pathogène a été confirmée par caractérisation morphologique, biochimique, physiologique et par tests des isolats sur feuille détachée. Résultats. Les prospections ont indiqué la présence du chancre citrique en Éthiopie. Sur feuilles, l'incidence globale a été de 71,4 % de feuilles avec au moins une lésion et la sévérité a été de 26,8 % de surface foliaire infectée. Sur fruits, l'incidence a été de 30 % de fruits infectés et la sévérité a été de 21,25 % de surface de fruit infectée. Les tests morphologiques, biochimiques, physiologiques et d'isolats sur feuille détachée ont indiqué des caractéristiques semblables à X. axonopodis pv. citri. La gamme d'hôtes du chancre citrique en Éthiopie a été limitée à la lime mexicaine (C. aurantifolia) et à l'orange amère (C. aurantium). Sur la base de cette gamme d'hôtes et des tests sur feuille isolée, il s'avère que le variant de X. axonopodis pv. citri qui s'exprime en Éthiopie a les mêmes hôtes que ceux de la forme asiatique atypique (Xac-A*). La sévérité du chancre a été significativement corrélée à la température mais pas aux précipitations, à l'altitude ou à l'âge de l'arbre. Conclusion. C'est la première fois que la présence de cette maladie est confirmée en Éthiopie.
Archives of Phytopathology and Plant Protection, Oct 2, 2018
Abstract Ginger bacterial wilt (GBW) is a destructive disease of ginger in Ethiopia. Field studie... more Abstract Ginger bacterial wilt (GBW) is a destructive disease of ginger in Ethiopia. Field studies were conducted to determine effect of integrated management of GBW, through host resistance and cultural practices, on wilt epidemics at Teppi and Jimma, southwestern Ethiopia in 2017. Treatments were factorial arranged in a randomised complete block design with three replications. Analysis of variance indicated that effect of variety, cultural practices and variety x cultural practice interactions significantly reduced GBW epidemic parameters and enhanced yield at both locations. Boziab recorded lower wilt incidence, area under disease progress curve and wilt progress rates than Local variety. Integration of lemon grass with soil solarisation and fertiliser reduced wilt incidence in Local variety up to 38.3% (Teppi) and 42.05% (Jimma) compared to the control on final wilt assessment date. In Boziab variety, integrated use of lemon grass with soil solarisation and fertiliser reduced wilt incidence up to 42.5% at Teppi and 33.85% at Jimma compared to the control on final date of wilt assessment. The overall results revealed that integrating cultural practices with host resistance are found effective to slow down GBW epidemics and improve ginger productivity; and thus, recommended for the study areas along with other crop management practices.
Asiatic citrus canker caused by Xanthomonas citri pv. citri (X. citri pv. citri-A) is detrimental... more Asiatic citrus canker caused by Xanthomonas citri pv. citri (X. citri pv. citri-A) is detrimental to citrus production in tropical and subtropical areas. The bacterium can cause severe infection on many citrus species, initially causing water-soaked leaf lesions that become erumpent and necrotic, often with a chlorotic halo. Severe infection causes premature fruit drop and twig dieback. X. citri pv. citri-A has consequently been subject to eradication and international quarantine regulations. In the 1990s, strains with a host range restricted to Mexican lime (Citrus aurantifolia), but not infecting grapefruit (C. paradisi), were described in different areas of Southwest Asia (4). This variant was designated X. citri pv. citri-A* because of its phenotypic and genetic similarities with X. citri pv. citri. Lime leaves with canker lesions were collected in 2007 from a citrus nursery in Kandal Province, Cambodia and isolations were performed with KC semiselective medium (3). Four Xanthomonas-like strains were further characterized by PCR alongside positive control strain CFBP 2525 from New Zealand. The expected DNA fragment was obtained using primer pair 4/7 (2) from the bacterial strains but not when distilled water was used as a template. Amplified fragment length polymorphism (AFLP) analysis of the four X. citri pv. citri strains from Cambodia and reference strains X. citri pv. citri-A (CFBP 2525, CFBP 2900, LMG 9322), -A* (CFBP 2911, JF90-2, JK2-10, JK143-1, JM47-2), and X. citri pv. aurantifolii (CFBP 2866, CFBP 2868, CFBP 2901) using SacI/MspI and four primer pairs (1) separated the Cambodian strains into two distinct haplotypes (i.e., AFLP fingerprint patterns). One haplotype was closely related (evolutionary genome divergences [EGD] ≤0.006 [1]) to X. citri pv. citri-A strains with a wide host range and the other was most genetically related to a strain of X. citri pv. citri-A* from Thailand (EGD of 0.003). On the basis of AFLP, the Cambodian isolates were not related to X. citri pv. aurantifolii (EGD values of &gt;0.060). When inoculated to Mexican lime and Duncan grapefruit using a detached leaf assay in which inoculum droplets containing ∼1 × 106 CFU were deposited on wounds (4), the strains genetically related to X. citri pv. citri-A produced typical canker lesions on both citrus species a week after inoculation, whereas the Cambodian strains related to X. citri pv. citri-A* by AFLP analysis only produced canker lesions on lime. Our finding extended the geographical distribution of pathotype A*. Identification of both pathotypes from a few samples collected in a nursery suggests a potential for large-scale distribution of these strains within the citrus orchards in Cambodia, where the most important citrus crop is sweet orange, suggesting that the occurrence of X. citri pv. citri-A* is of moderate economic significance, in contrast with X. citri pv. citri-A strains with a wide host range. Diseased citrus nursery plants are a major source of primary inoculum in developing countries. Sanitation of citrus nurseries against citrus canker in Cambodia is a prerequisite for improved management of the disease. References: (1) N. Ah-You et al. Phytopathology 97:1568, 2007. (2) J. S. Hartung et al. Phytopathology 86:95, 1996. (3) O. Pruvost et al. J. Appl. Microbiol. 99:803, 2005. (4) C. Vernière et al. Eur. J. Plant Pathol. 104:477, 1998.
Asiatic citrus canker caused by Xanthomonas citri pv. citri hinders national citrus markets in tr... more Asiatic citrus canker caused by Xanthomonas citri pv. citri hinders national citrus markets in tropical and subtropical areas and international trade. The bacterium induces erumpent, callus-like lesions causing defoliation, premature fruit drop, and twig dieback. Because of the damage caused by infection and reduced marketability of fruit, several countries have undergone eradication. Strains with different host ranges have been described. Pathotype A strains are the most widespread and produce canker in a wide range of citrus species. Pathotype A* strains with a host range restricted to Mexican lime (Citrus aurantifolia), Tahiti lime (C. latifolia), and alemow (C. macrophylla), but not infecting the susceptible species grapefruit (C. paradisi), were described in different areas of Asia (4). Reemergence of X. citri pv. citri pathotype A was recently described in Africa as affecting citrus production in Mali and Somalia. Canker-like infected citrus trees with symptoms on leaves, frui...
Variation of a representative range of Colletotrichum isolates from diseased coffee berries, samp... more Variation of a representative range of Colletotrichum isolates from diseased coffee berries, sampled from various regions in Ethiopia, was studied using morphological and pathological criteria. Spore suspensions from 4-week-old cultures of five isolates were applied to 8-week old seedlings, grown from known susceptible coffee cultivars, by wrapping strips of absorbent cotton wool dipped in inoculum around the seedlings. Substrate utilization of citrate and tartrate was assessed in stationary liquid. Morphological characters and conidial size were recorded. Random amplification of genomic DNA was done by PCR using 10 base primers. The seedling hypocotyl test confirmed variation in aggressiveness between the various isolates while biochemical tests and cultural characters showed that this was related to the occurrence of both Colletotrichum gloeosporioides and Colletotrichum kahawae in the range of isolates tested. PCR showed similar trends in the nucleotide sequence and did not differentiate between the isolates. The study showed that both C. kahawae and C. gloeosporioides occur in diseased berries, probably as sequential colonizers of diseased tissues.
A case of acute focal myocardial injury in a polymorbid female patient with intact coronary arter... more A case of acute focal myocardial injury in a polymorbid female patient with intact coronary arteries according to direct coronary angiography is reported. Acute focal myocardial injury was detected by ECG-synchronized perfusion single-photon emission computed tomogra-phy (SPECT) of the myocardium, and confirmed by the results of postmortem examination. The article also discusses the possibility of using perfusion SPECT to diagnose acute focal changes against the background of focal inflammatory myocardial infiltration.
Citrus canker: a new disease of Mexican lime (Citrus aurantifolia) and sour orange (C. aurantium)... more Citrus canker: a new disease of Mexican lime (Citrus aurantifolia) and sour orange (C. aurantium) in Ethiopia. Abstract --Introduction. Citrus canker, caused by the bacterium Xanthomonas axonopodis pv. citri, is a serious disease of most commercial citrus cultivars and some citrus relatives. Surveys were conducted in small-scale farms, commercial plantations, backyard orchards and nurseries in order to quantitatively study the occurrence and distribution of the disease and determine the intensity and field host range. Materials and methods. Seventeen locations in four regional states of Ethiopia were surveyed. Incidence on leaves was determined by counting total number of leaves and expressed as a proportion of leaves with at least one lesion. Incidence on fruits was determined on attached fruits, recorded as presence or absence of the symptoms. Severity was also measured on leaves and fruits. The identity of the pathogen was confirmed by morphological, biochemical and physiological characterization and detached leaf tests of representative isolates. Results. The surveys indicated the occurrence of citrus canker in Ethiopia. Overall incidence on leaves was 71.4% of leaves with at least one lesion and severity was 26.8% of leaf area infected. Incidence on fruits was 30% of fruits infected and severity was 21.25% fruit area infected. Morphological, biochemical and physiological characterization and detached leaf tests of isolates indicated characteristics similar to X. axonopodis pv. citri. The host range for citrus canker in Ethiopia was limited to Mexican lime (C. aurantifolia) and sour orange (C. aurantium). Based on the field host range and detached leaf tests, it appears that the X. axonopodis pv. citri variant that occurs in Ethiopia has similar host ranges to that of atypical Asiatic (Xac-A*) form. Canker severity significantly correlated with temperature but not with rainfall, elevation or tree age. Conclusion. This is the first confirmed report of the disease in Ethiopia. Citrus aurantium / Citrus aurantiifolia / Xanthomonas / plant diseases / pathogens / identification / geographical distribution / host plants Le chancre citrique : une nouvelle maladie de la lime mexicaine (Citrus aurantifolia) et de l'orange amère (C. aurantium) en Éthiopie. Résumé --Introduction. Le chancre citrique, provoqué par la bactérie Xanthomonas axonopodis pv. citri, est une maladie sérieuse de la plupart des cultivars commerciaux d'agrumes et d'autres genres voisins. Des prospections ont été conduites en exploitations de petite taille, en plantations commerciales, en vergers de case et en pépinières afin d'étudier quantitativement l'occurrence et la distribution de la maladie et d'en déterminer l'intensité et les hôtes. Matériel et méthodes. Dix-sept lieux répartis dans quatre États d'Éthiopie ont été visités. L'incidence sur feuilles a été exprimée par la proportion de feuilles portant au moins une lésion parmi l'ensemble des feuilles échantillonnées. L'incidence sur fruits a été déterminée sur les fruits sur arbre, en notant la présence ou l'absence des symptômes. La sévérité a été également mesurée sur feuilles et fruits. L'identité du pathogène a été confirmée par caractérisation morphologique, biochimique, physiologique et par tests des isolats sur feuille détachée. Résultats. Les prospections ont indiqué la présence du chancre citrique en Éthiopie. Sur feuilles, l'incidence globale a été de 71,4 % de feuilles avec au moins une lésion et la sévérité a été de 26,8 % de surface foliaire infectée. Sur fruits, l'incidence a été de 30 % de fruits infectés et la sévérité a été de 21,25 % de surface de fruit infectée. Les tests morphologiques, biochimiques, physiologiques et d'isolats sur feuille détachée ont indiqué des caractéristiques semblables à X. axonopodis pv. citri. La gamme d'hôtes du chancre citrique en Éthiopie a été limitée à la lime mexicaine (C. aurantifolia) et à l'orange amère (C. aurantium). Sur la base de cette gamme d'hôtes et des tests sur feuille isolée, il s'avère que le variant de X. axonopodis pv. citri qui s'exprime en Éthiopie a les mêmes hôtes que ceux de la forme asiatique atypique (Xac-A*). La sévérité du chancre a été significativement corrélée à la température mais pas aux précipitations, à l'altitude ou à l'âge de l'arbre. Conclusion. C'est la première fois que la présence de cette maladie est confirmée en Éthiopie.
Le genre des Citrus est sujet a un grand nombre de maladies economiquement impactantes. C'est... more Le genre des Citrus est sujet a un grand nombre de maladies economiquement impactantes. C'est le cas du Chancre Asiatique des Agrumes, cause par la bacterie Xathomonas citri pv. citri (Xcc). Organisme de quarantaine dans le bassin mediterraneen, ce pathogene est emergent dans plusieurs pays d'Afrique, dont l'Ethiopie en 2006 (1). Tres peu d'informations fiables sont disponibles pour reconstruire l'histoire de l'emergence de la maladie dans ce pays. A cette fin , nous avons entrepris des analyses de genetique des populations sur 8 vergers echantillonnes dans un meme paysage agrumicole, a l'aide de 14 marqueurs microsatellites. Des analyses descriptives classiques confirment le statut epidemique de la population Ethiopienne et suggerent que les plantations auraient ete infectees a partie d'une meme source non echantillonnee. Ce scenario semble etre par ailleurs plausible compte tenu de l'organisation locale des plantations qui partagent une meme pep...
International journal of food science and agriculture
Coffee is a non-alcoholic and stimulant beverage crop and belongs to the family Rubiaceae and gen... more Coffee is a non-alcoholic and stimulant beverage crop and belongs to the family Rubiaceae and genus Coffea. Arabica coffee (Coffea arabica L.) has been threatened by various coffee fungal diseases. Among these coffee berry disease (CBD) is the most economically important one in East African countries including Ethiopia. Coffee berry disease (CBD) caused by Colletotrichum kahawae was intensively assessed and examined in 90 sample coffee farms from 3 coffee growing districts (Chole, Gololcha and Shanan Kolu) of Arsi, Southeastern Ethiopia. Assessment was done to examine prevalence, incidence and severity of CBD in selected districts. Assessment was done visually, random sampling techniques and interviewing growers for important points related to CBD. Coffee berry disease was prevalent in most surveyed coffee growing areas of Arsi. The overall mean prevalence, incidence and severity of CBD were 85.52, 49.78 and 19.25%, respectively. The highest incidence (100%) and severity (55.14 %) of CBD were observed in Shanan Kolu, followed by Gololcha, 80 and 54.18% and Chole, 80 and 42.73%. High CBD severity and incidence were recorded at the high land of selected districts. In order to reduce CBD intensity in the respective areas, research should be able to develop CBD resistant coffee varieties through screening landraces using virulent pathogens. Similarly, proper cultural practices, such as coffee pruning, shade tree regulation, application of organic fertilizers and wider spacing should be utilized by coffee growers to reduce CBD intensity throughout their coffee ecosystem.
Ethiopia mainly uses resistant varieties and cultural disease management strategies to tackle thi... more Ethiopia mainly uses resistant varieties and cultural disease management strategies to tackle this disease. However, still there is a lack of improved and resistant varieties in coffee growing areas of the country including Arsi Zone. The objectives of this study were to investigate the resistance of Arsi coffee collections to Coffee Berry Disease through arti cial inoculation of green berries on mother trees, and younger coffee seedlings under controlled conditions. The eld experiment was conducted at Gololcha (Arbagugu state farm) and Mechara Agricultural research center on station. A hypocotyl test was conducted at Jimma Agricultural research center. Field test was carried out on 13 Arsi coffee collections and the Coffee Berry Disease -susceptible Arusa coffee variety. Standard checks like susceptible variety (370) and resistant varieties 741 and 754 were used for hypocotyl tests. Seventeen treatments were used for hypocotyl tests. Result showed the presence of a signi cant difference in Coffee Berry Disease reaction levels among genotypes (P < 0.001) under eld conditions. The infection percentage of berries varied from 2.89 to 25.93% at Gololcha (Arbagugu state farm) and 3.25 to 34.92% at Mechara three weeks after treatment applications. According to the results, the resistant variety 741 showed the lowest infection percentage (15.04%) in comparison to all other collections and/or varieties at the seedling stage. Therefore, coffee collections that showed the lowest level of infection percentage under both experimental conditions (Ar15/11, Ar05/11, and Ar70/11) were recommended for further breeding strategies to develop resistant coffee varieties against the disease.
Citrus canker: a new disease of Mexican lime (Citrus aurantifolia) and sour orange (C. aurantium)... more Citrus canker: a new disease of Mexican lime (Citrus aurantifolia) and sour orange (C. aurantium) in Ethiopia. Abstract-Introduction. Citrus canker, caused by the bacterium Xanthomonas axonopodis pv. citri, is a serious disease of most commercial citrus cultivars and some citrus relatives. Surveys were conducted in small-scale farms, commercial plantations, backyard orchards and nurseries in order to quantitatively study the occurrence and distribution of the disease and determine the intensity and field host range. Materials and methods. Seventeen locations in four regional states of Ethiopia were surveyed. Incidence on leaves was determined by counting total number of leaves and expressed as a proportion of leaves with at least one lesion. Incidence on fruits was determined on attached fruits, recorded as presence or absence of the symptoms. Severity was also measured on leaves and fruits. The identity of the pathogen was confirmed by morphological, biochemical and physiological characterization and detached leaf tests of representative isolates. Results. The surveys indicated the occurrence of citrus canker in Ethiopia. Overall incidence on leaves was 71.4% of leaves with at least one lesion and severity was 26.8% of leaf area infected. Incidence on fruits was 30% of fruits infected and severity was 21.25% fruit area infected. Morphological, biochemical and physiological characterization and detached leaf tests of isolates indicated characteristics similar to X. axonopodis pv. citri. The host range for citrus canker in Ethiopia was limited to Mexican lime (C. aurantifolia) and sour orange (C. aurantium). Based on the field host range and detached leaf tests, it appears that the X. axonopodis pv. citri variant that occurs in Ethiopia has similar host ranges to that of atypical Asiatic (Xac-A*) form. Canker severity significantly correlated with temperature but not with rainfall, elevation or tree age. Conclusion. This is the first confirmed report of the disease in Ethiopia. Ethiopia / Citrus aurantium / Citrus aurantiifolia / Xanthomonas / plant diseases / pathogens / identification / geographical distribution / host plants Le chancre citrique : une nouvelle maladie de la lime mexicaine (Citrus aurantifolia) et de l'orange amère (C. aurantium) en Éthiopie. Résumé-Introduction. Le chancre citrique, provoqué par la bactérie Xanthomonas axonopodis pv. citri, est une maladie sérieuse de la plupart des cultivars commerciaux d'agrumes et d'autres genres voisins. Des prospections ont été conduites en exploitations de petite taille, en plantations commerciales, en vergers de case et en pépinières afin d'étudier quantitativement l'occurrence et la distribution de la maladie et d'en déterminer l'intensité et les hôtes. Matériel et méthodes. Dix-sept lieux répartis dans quatre États d'Éthiopie ont été visités. L'incidence sur feuilles a été exprimée par la proportion de feuilles portant au moins une lésion parmi l'ensemble des feuilles échantillonnées. L'incidence sur fruits a été déterminée sur les fruits sur arbre, en notant la présence ou l'absence des symptômes. La sévérité a été également mesurée sur feuilles et fruits. L'identité du pathogène a été confirmée par caractérisation morphologique, biochimique, physiologique et par tests des isolats sur feuille détachée. Résultats. Les prospections ont indiqué la présence du chancre citrique en Éthiopie. Sur feuilles, l'incidence globale a été de 71,4 % de feuilles avec au moins une lésion et la sévérité a été de 26,8 % de surface foliaire infectée. Sur fruits, l'incidence a été de 30 % de fruits infectés et la sévérité a été de 21,25 % de surface de fruit infectée. Les tests morphologiques, biochimiques, physiologiques et d'isolats sur feuille détachée ont indiqué des caractéristiques semblables à X. axonopodis pv. citri. La gamme d'hôtes du chancre citrique en Éthiopie a été limitée à la lime mexicaine (C. aurantifolia) et à l'orange amère (C. aurantium). Sur la base de cette gamme d'hôtes et des tests sur feuille isolée, il s'avère que le variant de X. axonopodis pv. citri qui s'exprime en Éthiopie a les mêmes hôtes que ceux de la forme asiatique atypique (Xac-A*). La sévérité du chancre a été significativement corrélée à la température mais pas aux précipitations, à l'altitude ou à l'âge de l'arbre. Conclusion. C'est la première fois que la présence de cette maladie est confirmée en Éthiopie.
Archives of Phytopathology and Plant Protection, Oct 2, 2018
Abstract Ginger bacterial wilt (GBW) is a destructive disease of ginger in Ethiopia. Field studie... more Abstract Ginger bacterial wilt (GBW) is a destructive disease of ginger in Ethiopia. Field studies were conducted to determine effect of integrated management of GBW, through host resistance and cultural practices, on wilt epidemics at Teppi and Jimma, southwestern Ethiopia in 2017. Treatments were factorial arranged in a randomised complete block design with three replications. Analysis of variance indicated that effect of variety, cultural practices and variety x cultural practice interactions significantly reduced GBW epidemic parameters and enhanced yield at both locations. Boziab recorded lower wilt incidence, area under disease progress curve and wilt progress rates than Local variety. Integration of lemon grass with soil solarisation and fertiliser reduced wilt incidence in Local variety up to 38.3% (Teppi) and 42.05% (Jimma) compared to the control on final wilt assessment date. In Boziab variety, integrated use of lemon grass with soil solarisation and fertiliser reduced wilt incidence up to 42.5% at Teppi and 33.85% at Jimma compared to the control on final date of wilt assessment. The overall results revealed that integrating cultural practices with host resistance are found effective to slow down GBW epidemics and improve ginger productivity; and thus, recommended for the study areas along with other crop management practices.
Asiatic citrus canker caused by Xanthomonas citri pv. citri (X. citri pv. citri-A) is detrimental... more Asiatic citrus canker caused by Xanthomonas citri pv. citri (X. citri pv. citri-A) is detrimental to citrus production in tropical and subtropical areas. The bacterium can cause severe infection on many citrus species, initially causing water-soaked leaf lesions that become erumpent and necrotic, often with a chlorotic halo. Severe infection causes premature fruit drop and twig dieback. X. citri pv. citri-A has consequently been subject to eradication and international quarantine regulations. In the 1990s, strains with a host range restricted to Mexican lime (Citrus aurantifolia), but not infecting grapefruit (C. paradisi), were described in different areas of Southwest Asia (4). This variant was designated X. citri pv. citri-A* because of its phenotypic and genetic similarities with X. citri pv. citri. Lime leaves with canker lesions were collected in 2007 from a citrus nursery in Kandal Province, Cambodia and isolations were performed with KC semiselective medium (3). Four Xanthomonas-like strains were further characterized by PCR alongside positive control strain CFBP 2525 from New Zealand. The expected DNA fragment was obtained using primer pair 4/7 (2) from the bacterial strains but not when distilled water was used as a template. Amplified fragment length polymorphism (AFLP) analysis of the four X. citri pv. citri strains from Cambodia and reference strains X. citri pv. citri-A (CFBP 2525, CFBP 2900, LMG 9322), -A* (CFBP 2911, JF90-2, JK2-10, JK143-1, JM47-2), and X. citri pv. aurantifolii (CFBP 2866, CFBP 2868, CFBP 2901) using SacI/MspI and four primer pairs (1) separated the Cambodian strains into two distinct haplotypes (i.e., AFLP fingerprint patterns). One haplotype was closely related (evolutionary genome divergences [EGD] ≤0.006 [1]) to X. citri pv. citri-A strains with a wide host range and the other was most genetically related to a strain of X. citri pv. citri-A* from Thailand (EGD of 0.003). On the basis of AFLP, the Cambodian isolates were not related to X. citri pv. aurantifolii (EGD values of &gt;0.060). When inoculated to Mexican lime and Duncan grapefruit using a detached leaf assay in which inoculum droplets containing ∼1 × 106 CFU were deposited on wounds (4), the strains genetically related to X. citri pv. citri-A produced typical canker lesions on both citrus species a week after inoculation, whereas the Cambodian strains related to X. citri pv. citri-A* by AFLP analysis only produced canker lesions on lime. Our finding extended the geographical distribution of pathotype A*. Identification of both pathotypes from a few samples collected in a nursery suggests a potential for large-scale distribution of these strains within the citrus orchards in Cambodia, where the most important citrus crop is sweet orange, suggesting that the occurrence of X. citri pv. citri-A* is of moderate economic significance, in contrast with X. citri pv. citri-A strains with a wide host range. Diseased citrus nursery plants are a major source of primary inoculum in developing countries. Sanitation of citrus nurseries against citrus canker in Cambodia is a prerequisite for improved management of the disease. References: (1) N. Ah-You et al. Phytopathology 97:1568, 2007. (2) J. S. Hartung et al. Phytopathology 86:95, 1996. (3) O. Pruvost et al. J. Appl. Microbiol. 99:803, 2005. (4) C. Vernière et al. Eur. J. Plant Pathol. 104:477, 1998.
Asiatic citrus canker caused by Xanthomonas citri pv. citri hinders national citrus markets in tr... more Asiatic citrus canker caused by Xanthomonas citri pv. citri hinders national citrus markets in tropical and subtropical areas and international trade. The bacterium induces erumpent, callus-like lesions causing defoliation, premature fruit drop, and twig dieback. Because of the damage caused by infection and reduced marketability of fruit, several countries have undergone eradication. Strains with different host ranges have been described. Pathotype A strains are the most widespread and produce canker in a wide range of citrus species. Pathotype A* strains with a host range restricted to Mexican lime (Citrus aurantifolia), Tahiti lime (C. latifolia), and alemow (C. macrophylla), but not infecting the susceptible species grapefruit (C. paradisi), were described in different areas of Asia (4). Reemergence of X. citri pv. citri pathotype A was recently described in Africa as affecting citrus production in Mali and Somalia. Canker-like infected citrus trees with symptoms on leaves, frui...
Variation of a representative range of Colletotrichum isolates from diseased coffee berries, samp... more Variation of a representative range of Colletotrichum isolates from diseased coffee berries, sampled from various regions in Ethiopia, was studied using morphological and pathological criteria. Spore suspensions from 4-week-old cultures of five isolates were applied to 8-week old seedlings, grown from known susceptible coffee cultivars, by wrapping strips of absorbent cotton wool dipped in inoculum around the seedlings. Substrate utilization of citrate and tartrate was assessed in stationary liquid. Morphological characters and conidial size were recorded. Random amplification of genomic DNA was done by PCR using 10 base primers. The seedling hypocotyl test confirmed variation in aggressiveness between the various isolates while biochemical tests and cultural characters showed that this was related to the occurrence of both Colletotrichum gloeosporioides and Colletotrichum kahawae in the range of isolates tested. PCR showed similar trends in the nucleotide sequence and did not differentiate between the isolates. The study showed that both C. kahawae and C. gloeosporioides occur in diseased berries, probably as sequential colonizers of diseased tissues.
A case of acute focal myocardial injury in a polymorbid female patient with intact coronary arter... more A case of acute focal myocardial injury in a polymorbid female patient with intact coronary arteries according to direct coronary angiography is reported. Acute focal myocardial injury was detected by ECG-synchronized perfusion single-photon emission computed tomogra-phy (SPECT) of the myocardium, and confirmed by the results of postmortem examination. The article also discusses the possibility of using perfusion SPECT to diagnose acute focal changes against the background of focal inflammatory myocardial infiltration.
Citrus canker: a new disease of Mexican lime (Citrus aurantifolia) and sour orange (C. aurantium)... more Citrus canker: a new disease of Mexican lime (Citrus aurantifolia) and sour orange (C. aurantium) in Ethiopia. Abstract --Introduction. Citrus canker, caused by the bacterium Xanthomonas axonopodis pv. citri, is a serious disease of most commercial citrus cultivars and some citrus relatives. Surveys were conducted in small-scale farms, commercial plantations, backyard orchards and nurseries in order to quantitatively study the occurrence and distribution of the disease and determine the intensity and field host range. Materials and methods. Seventeen locations in four regional states of Ethiopia were surveyed. Incidence on leaves was determined by counting total number of leaves and expressed as a proportion of leaves with at least one lesion. Incidence on fruits was determined on attached fruits, recorded as presence or absence of the symptoms. Severity was also measured on leaves and fruits. The identity of the pathogen was confirmed by morphological, biochemical and physiological characterization and detached leaf tests of representative isolates. Results. The surveys indicated the occurrence of citrus canker in Ethiopia. Overall incidence on leaves was 71.4% of leaves with at least one lesion and severity was 26.8% of leaf area infected. Incidence on fruits was 30% of fruits infected and severity was 21.25% fruit area infected. Morphological, biochemical and physiological characterization and detached leaf tests of isolates indicated characteristics similar to X. axonopodis pv. citri. The host range for citrus canker in Ethiopia was limited to Mexican lime (C. aurantifolia) and sour orange (C. aurantium). Based on the field host range and detached leaf tests, it appears that the X. axonopodis pv. citri variant that occurs in Ethiopia has similar host ranges to that of atypical Asiatic (Xac-A*) form. Canker severity significantly correlated with temperature but not with rainfall, elevation or tree age. Conclusion. This is the first confirmed report of the disease in Ethiopia. Citrus aurantium / Citrus aurantiifolia / Xanthomonas / plant diseases / pathogens / identification / geographical distribution / host plants Le chancre citrique : une nouvelle maladie de la lime mexicaine (Citrus aurantifolia) et de l'orange amère (C. aurantium) en Éthiopie. Résumé --Introduction. Le chancre citrique, provoqué par la bactérie Xanthomonas axonopodis pv. citri, est une maladie sérieuse de la plupart des cultivars commerciaux d'agrumes et d'autres genres voisins. Des prospections ont été conduites en exploitations de petite taille, en plantations commerciales, en vergers de case et en pépinières afin d'étudier quantitativement l'occurrence et la distribution de la maladie et d'en déterminer l'intensité et les hôtes. Matériel et méthodes. Dix-sept lieux répartis dans quatre États d'Éthiopie ont été visités. L'incidence sur feuilles a été exprimée par la proportion de feuilles portant au moins une lésion parmi l'ensemble des feuilles échantillonnées. L'incidence sur fruits a été déterminée sur les fruits sur arbre, en notant la présence ou l'absence des symptômes. La sévérité a été également mesurée sur feuilles et fruits. L'identité du pathogène a été confirmée par caractérisation morphologique, biochimique, physiologique et par tests des isolats sur feuille détachée. Résultats. Les prospections ont indiqué la présence du chancre citrique en Éthiopie. Sur feuilles, l'incidence globale a été de 71,4 % de feuilles avec au moins une lésion et la sévérité a été de 26,8 % de surface foliaire infectée. Sur fruits, l'incidence a été de 30 % de fruits infectés et la sévérité a été de 21,25 % de surface de fruit infectée. Les tests morphologiques, biochimiques, physiologiques et d'isolats sur feuille détachée ont indiqué des caractéristiques semblables à X. axonopodis pv. citri. La gamme d'hôtes du chancre citrique en Éthiopie a été limitée à la lime mexicaine (C. aurantifolia) et à l'orange amère (C. aurantium). Sur la base de cette gamme d'hôtes et des tests sur feuille isolée, il s'avère que le variant de X. axonopodis pv. citri qui s'exprime en Éthiopie a les mêmes hôtes que ceux de la forme asiatique atypique (Xac-A*). La sévérité du chancre a été significativement corrélée à la température mais pas aux précipitations, à l'altitude ou à l'âge de l'arbre. Conclusion. C'est la première fois que la présence de cette maladie est confirmée en Éthiopie.
Le genre des Citrus est sujet a un grand nombre de maladies economiquement impactantes. C'est... more Le genre des Citrus est sujet a un grand nombre de maladies economiquement impactantes. C'est le cas du Chancre Asiatique des Agrumes, cause par la bacterie Xathomonas citri pv. citri (Xcc). Organisme de quarantaine dans le bassin mediterraneen, ce pathogene est emergent dans plusieurs pays d'Afrique, dont l'Ethiopie en 2006 (1). Tres peu d'informations fiables sont disponibles pour reconstruire l'histoire de l'emergence de la maladie dans ce pays. A cette fin , nous avons entrepris des analyses de genetique des populations sur 8 vergers echantillonnes dans un meme paysage agrumicole, a l'aide de 14 marqueurs microsatellites. Des analyses descriptives classiques confirment le statut epidemique de la population Ethiopienne et suggerent que les plantations auraient ete infectees a partie d'une meme source non echantillonnee. Ce scenario semble etre par ailleurs plausible compte tenu de l'organisation locale des plantations qui partagent une meme pep...
International journal of food science and agriculture
Coffee is a non-alcoholic and stimulant beverage crop and belongs to the family Rubiaceae and gen... more Coffee is a non-alcoholic and stimulant beverage crop and belongs to the family Rubiaceae and genus Coffea. Arabica coffee (Coffea arabica L.) has been threatened by various coffee fungal diseases. Among these coffee berry disease (CBD) is the most economically important one in East African countries including Ethiopia. Coffee berry disease (CBD) caused by Colletotrichum kahawae was intensively assessed and examined in 90 sample coffee farms from 3 coffee growing districts (Chole, Gololcha and Shanan Kolu) of Arsi, Southeastern Ethiopia. Assessment was done to examine prevalence, incidence and severity of CBD in selected districts. Assessment was done visually, random sampling techniques and interviewing growers for important points related to CBD. Coffee berry disease was prevalent in most surveyed coffee growing areas of Arsi. The overall mean prevalence, incidence and severity of CBD were 85.52, 49.78 and 19.25%, respectively. The highest incidence (100%) and severity (55.14 %) of CBD were observed in Shanan Kolu, followed by Gololcha, 80 and 54.18% and Chole, 80 and 42.73%. High CBD severity and incidence were recorded at the high land of selected districts. In order to reduce CBD intensity in the respective areas, research should be able to develop CBD resistant coffee varieties through screening landraces using virulent pathogens. Similarly, proper cultural practices, such as coffee pruning, shade tree regulation, application of organic fertilizers and wider spacing should be utilized by coffee growers to reduce CBD intensity throughout their coffee ecosystem.
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