Abstract:
Coffee berry disease caused by fungus Colletotrichum kahawae, is considered as major disease
of coffee in Ethiopia. Different control methods practiced at coffee producing farms and farmer
levels in the country including chemical control. Hence, the use of chemical fungicide is causes
environmental pollution and abortion of natural sustainability. However, the development of
biological control helps to improve plant health, yield, reduce health risk and hazardous effects
on environments have got great concern. Hereafter, this study was carried out to examine the
antagonistic effects of rhizobacteria isolated from Arabica Coffee rhizosphere against
Colletotrichum kahawae, that causes coffee berry disease, under in vitro and in vivo
conditions. The soil sample used sources of bacteria were taken from Gera, Ela Dalle and
around the JUCAVM campus. The isolation result showed that, total of 215 isolated from Gera
(104), Ela dale (67) and JUCAVM campus (44) in ten different bacteria species on Kings B
medium. The isolated bacteria were in-vitro tested by using CRD with three replications. Out of
215 isolated rhizobacteria antagonistic tested on Half Strength King’s B (HSKB) medium, 28
exhibited remarkable range of 8.2% – 91.3% C. kahawae radial growth inhibition and four
rhizobacteria; Bacillus spp. (JU544) by 91.3%, Pseudomonas spp. (JU13) by 82.3%, Bacillus
spp. (JU735 by 74.6%, and Micrococcus spp. (JU533) with 67% showed high inhibition
percentage. High performed rhizobacteria were tested under in vivo condition against the
fungal pathogen on detached green coffee berry, by applying the isolates at the same time of
inoculation, 48 hours before and after inoculation of the pathogen. The results at both severity
and incidence showed that Bacillus spp. (JU544) and Pseudomonas spp. (JU13) genera were
the most effective that significantly reduced (p<0.0001) the radial culture growth of the
pathogen when compared to the control, respectively. Furthermore, Bacillus spp. (JU544) and
Pseudomonas spp. (JU13) genera consistently reduced disease severity and incidence when
applied at the same time than applying before 48hrs and 48 hours after inoculation on
detached coffee berries. However, the highest bio-control efficiency reduced disease severity
and disease incidence was 89% and 76.7% when the coffee berry was treated
with Bacillus spp. (JU544) at the same time with inoculation of the pathogen. Thus,
considerable efforts should be devoted on isolation, identification of the plant growth
promoting rhizobacteria and to evaluate the genera’s effectiveness against the coffee berry
disease causing pathogen. In order to develop new microbial fungicides as alternative to
control and fight berry anthracnose and as well as to formulate integrated disease management
schedule and come up with strong recommendation. This study was conducted under
laboratory conditions. Moreover, optimum concentration, application methods of rhizobacteria
should be studied. Further conformation may be also important.
