Evaluation of Biological Control Agents Against Bacterial WiltPathogen (Xanthomonas campestris pv. musacearum) of Ensete(Ensete ventricosum)
No Thumbnail Available
Date
2010-11
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Addis Ababa University
Abstract
The present study was designed with the objective of isolating, screening, evaluating and
characterizing antagonistic isolates against bacterial wilt of ensete from rhizosphere and phyllosphere
of the host. A total of 361 bacterial and 145 fungal colonies were isolated. The in vitro antagonistic
test on the pathogen showed that 17 fungal isolates and 3 bacterial isolates were screened to be active
against the pathogen on the appropriate media with inhibition diameters ranging from 5mm to 40 mm.
This indicates that the bacterial antagonists were more effective than fungal antagonists to inhibit the
test microorganism with inhibition diameters ranging from 32mm to 40mm whereas the fungal
antagonists were more diverse in their effectiveness than bacterial antagonists with inhibition
diameters from 5mm to 21mm. The most effective antagonistic isolates (AUFB1, AUFB2, AUFB2,
AUFB11, AUFB17, AUFB15, AUbB, AUbB1 and AUbB2) were characterized and identified to their
genus level. The isolates AUbB1, AUbB3 and AUbB3 (bacteria) were identified as Pseudomonas. The
fungal isolates AUFB2 and AUFB11 were categorized into Trichoderma, isolates AUFB1, AUFB15
and AUFB19 were classified as Penicillium and the isolate AUFB3 was identified as Verticillium.
These isolates were further tested for antagonistic and plant growth promoting properties. It has been
found that two bacterial isolates AUFB1, AUFB2 produced indole acetic acid, protease and solubilize
inorganic phosphate whereas the isolate AUbB3 (bacterium) produced hydrogen cyanide, indole acetic
acid and solubilize inorganic phosphate. It was also recorded that two fungal isolates AUFB15 and
AUFB11 produced HCN and protease but the isolate AUFB15 was also produced indole acetic acid
and solublize inorganic phosphate. In vivo under green house condition four effective isolates AUbB3,
AUbB1, AUbB2 (bacteria) and AUFB11 (fungus) were evaluated for their efficacy against the
pathogen. The data showed that the isolates AUbB1, AUbB3, AUbB2 and AUbB11 reduced the
disease severity of ensete wilt with DSR (disease severity reduction) 74.8, 62.4, 57.4, and 56.4%,
respectively. The isolate AUbB1 (bacterium) showed highest DSR whereas the isolate AUbB11
(fungus) showed least DSR. The isolates which showed significance pathogen reduction in vitro test
and under green house conditions should be checked under field trials to further confirm their efficacy
and to use them as antagonists. The result will serve as base line data for future endeavor of utilizing
biological control system of ensete to increase productivity into low-input agriculture of the regionand the country at large.
Key words: Ensete, Xanthomonas campestris pv. musacearum, Fungal and bacterial antagonist
Description
Keywords
Ensete, Xanthomonas campestris pv, musacearum, Fungal and bacterial antagonist