Distribution and Diversity of Fungi and Their Biocontrol Potential in Managing Coffee Berry Disease in Kirinyaga County Kenya
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Date
2024-11
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Kenyatta University
Abstract
Coffee is among the major traded goods across the world after oil. Its production in
Kenya faces constraints majorly coffee berry disease (CBD) which is caused by the
fungus Colletotrichum kahawae. Diversity of biological species confers essential
benefits in creating sustainability which contributes to increase in diversity thereby
providing resistance to disturbance and stress, and change in conditions in the soil.
Understanding the diversity of microorganisms in berries and soils from coffee farms
could be of importance in determining which of these micro-organisms could control
the disease. The significance of this study was to isolate and identify fungi from
different zones in coffee farms in Kirinyaga County Kenya with an aim of further
studying their biocontrol potential to Colletotrichum kahawae. One hundred (100)
coffee farms were sampled. The species of fungal were isolated from coffee berries;
soil and from Upper Midland 1, 2 and 3. The berries of coffee were washed and
allowed to sporulate for 24hrs. Lesions were excised, suspended in distilled water and
serial dilutions made. This was plated in potato dextrose agar (PDA) and incubated at
room temperature for ten days. Fungi was isolated from soil by inoculating 1ml from
serial dilutions 10-3
on PDA and incubating at room temperature for ten days.
Recovered colonies were sub cultured individually by inoculating the spores scooped
from the culture into a separate plate with PDA. Identification of fungi at the genus
level was carried out by using macroscopic and microscopic examination. Five
isolates were tested for antagonism against CBD by co culturing 3cm diameter discs
of the test isolate and the pathogen on PDA media. The degree of antagonism was
determined by measuring and comparing the radial growth of pathogen with the bio agent against the control. Fungi were identified as Colletotrichum, Phoma,
Trichoderma, Epichoccum, Aspergillus, Alternaria, Fusarium, Rhizopus, Penicillium,
and Cladosporium. The results indicated that Colletotrichum and Cladosporium were
the most abundant in the berries at 76% for both species. Fusarium and Cladosporium
were the most abundant in soil at 50% and 20% respectively. From the five isolates
that were tested against C. kahawae, two isolates Penicillium and Fusarium
proliferetum significantly inhibited growth of the test pathogen at 55% and 60%
respectively. The remaining isolates Aspergillus fumigatus, Chaetomium perithecia
and Fusarium Ceraneasum showed inhibition of growth at 40%, 18.18 %, and 45.45%
respectively. Statistical analysis (p<0.05) indicated significance difference of distance
of growth between the potential isolates with a higher growth inhibition to the test
pathogen against control. The test results indicated the potential of utilizing
saprophytic coffee surface micro flora and rhizosphere fungi in bio control of the
coffee berry disease upon further verification of the species of fusarium not being a
disease causing agent
Description
Thesis Submitted in Partial Fulfillment of the Requirements for the Award of the Degree of Masters of Science (Biotechnology) in the School of Pure and Applied Sciences of Kenyatta University, November, 2024
Supervisor;
1. Steven Rono
2. Titus Magomere