The Potential of Fungi as Bio-Control Agents in Managing Colletotrichum Kahawae In Kenya

Colletotrichum kahawae is a causative fungal agent of Coffee Berry Disease (CBD) that negatively affects coffee production. Its control relies on use of resistant varieties and chemical control. Fungicides used in control of CBD are costly and pose a risk to environment and health. The study was aimed at assessing the possible antagonistic potential of fungal isolates against Colletotrichum kahawae in in vitro conditions. Five isolates were used; one isolate was collected from berries while the rest were collected from soil. Testing for antagonism against Colletorichum kahawae was done by co-culturing the isolates on Potato Dextrose Agar. The degree of antagonism was determined by measuring and comparing the radial growth of pathogen with the bio-agent against the control. Out of the five isolates tested against C. kahawae, three isolates Fusarium proliferetum, Penicillium and Fusarium ceraneasum significantly inhibited test pathogen growth at 60%, 55% and 45.45%, respectively. The other isolates, Fumigatus aspergillus and Chaetomium perithecia showed inhibition of growth at 40% and 18.18% respectively. It was concluded that there is potential of using fungi as bio control of the coffee berry disease.

Efficacy of Two New Fungicides Against Colletotrichum Kahawae Infecting Coffee in Kenya

Coffee Berry Disease(CBD) caused by Colletotrichum kahawae is a destructive fungal disease of coffee in Kenya, leading to a loss of about 75%. This study aimed to assess the In Vitro efficacy of two fungicides:- CRI 1 (Pyraclostrobin 150 g/L + Fluxapyroxad 75 g/L) and CRI 2 (Pyraclostrobin 128 g/Kg + Boscalid 252 g/Kg) against C. kahawae using poisoned food technique on Potato Dextrose Agar. A total of 170 coffee berries with C. kahawae symptoms were purposively collected from both sprayed and unsprayed plots. Ten rates of each of the two fungicides were assessed ranging from 0.01% to 0.1% at an interval of 0.01%. Two commercial standard fungicides Pyraclostrobin 250 g/L at 0.04% and Tebuconazole 200 g/L + Trifloxystrobin 100 g/L at 0.1% were used as positive controls. Fungal inoculum in PDA media devoid of the fungicide acted as the negative control. Data on colony diameter was collected after every 24 hours for 13 days. Analysis of Variance (ANOVA) of the data on colony diameter was done using CoStat software version 6.400. The results revealed that all the rates of CRI 1 and CRI 2 fungicides controlled the colony diameter of C. kahawae compared to the control treatment. CRI 1 fungicide suppressed the growth of C. kahawae even at the lowest concentration of 0.01% with a percentage control of 64.74 %. The highest concentration of 0.1% had a percentage control of 66.15% . CRI 1 is more effective in controlling C. kahawae since it controls the fungus at a rate even lower than Pyraclostrobin 250 g/L which had a percentage control of 66.10 at a recommended rate of 0.04% and Tebuconazole 200 g/L + Trifloxystrobin 100 g/L fungicides which had a percentage control of 65.76 at a recommended rate of 0.1%. CRI 1 also hade a better percentage control as compared to CRI 2. CRI 2 had a percentage control of 54.63% at the highest rate of 0.1% and a percentage control of 35.60% at the lowest rate of 0.01% . Further studies on CRI 1 and CRI 2 fungicides should be carried out for yield assessment in the field.

Characterization and virulence determination of Colletotrichum kahawae isolates from Gidami, Western Ethiopia

Coffee is one of the most essential crops that generate income for Ethiopian economic growth. However, its production faced with many factors primarily biotic entities. Among these, the fungal pathogen /Colletotrichum kahawae/ that induce coffee berry disease (CBD) is the main constraint of coffee production in the country. The pathogen is a very specialized and infects the green berries/fiscal par/which diminishes the income gained from it and disturbs the country’s economy in general and the producers in particular. Regarding to the disease level and related factors, little information is available in Western Ethiopia. Hence, this study was initiated to assess the magnitude of CBD in coffee fields, to characterize and evaluate the virulence of C. kahawae isolates from the study areas of Gidami district. Assessment was done in 9 selected kebeles of 45 total farms starting from July 2017. The results indicated that CBD was prevalence in all assessed areas with the range of 66% to 86% and 16% to 50% disease incidence and severity index (SI), respectively. The highest CBD intensity was observed in higher altitude with a significant positive correlation between disease incidence (r = 0.61) and severity (r = 0.55). Macro and microscopic characterization results revealed isolates diversity in terms of colony color, density, mycelia growth rate and conidial production. Moreover, mycelia growth rate differs significantly (p < 0.001) in the range between 2.2 to 4.3 mm/24 hrs. Similarly, the sporulation capacity widely ranged from 186.1 to 572.3 spores/ml. This were strongly agreed with the virulence test that revealed significant variation (p < 0.001) among isolates and infection percentage also ranged between 34.8% and 88.7%. In all, the study was not only showed the CBD is very important disease of coffee in the study area but also determines the virulence disparity among isolates. To be honest, the diversity/identity of C. kahawae isolates should be confirmed using more other reliable methods thru including additional sample areas as well.

Resistencia genética a la Enfermedad de la Cereza del Café en variedades cultivadas en Colombia.

La enfermedad de las cerezas del café (CBD), antracnosis causada por el hongo Colletotrichum kahawae subsp. kahawae, ha sido registrada solo en África y puede ocasionar pérdidas de producción hasta del 80%. Cenicafé desarrolla variedades resistentes a las enfermedades más limitantes para el cultivo, aún en ausencia de los patógenos en Colombia, usando al Híbrido de Timor (HT) como la principal fuente de resistencia a la roya del cafeto y a CBD. El propósito de este estudio fue conocer la presencia del gen Ck-1 de resistencia a CBD en las principales variedades de café cultivadas en Colombia, establecer la correlación entre la presencia de Ck-1 y la respuesta a inoculación de hipocótilos y explorar las bases genómicas de la resistencia. Los marcadores moleculares ligados a Ck-1 se ubicaron en el cromosoma 1 de Coffea canephora, región genómica con quince genes de resistencia a enfermedades. Se encontraron marcadores para Ck-1 en todas las líneas mejoradas derivadas del HT-1343 y ausentes en las variedades Típica, Borbón y Caturra, y en líneas derivadas del HT-832/1. No hubo correlación entre las formas alélicas de resistencia a CBD y la resistencia medida por inoculación de hipocótilos. La alta frecuencia de formas alélicas asociadas con resistencia a CBD en materiales seleccionados por resistencia a roya sugiere cosegregación de genes de resistencia para ambas enfermedades. La estrategia de variedades multilínea desarrolladas por Cenicafé, que actualmente corresponde a cerca del 80% del café sembrado en el país, hace que la población en general esté protegida ante la eventual llegada del patógeno a Colombia.