Download ABSTRACT - Otadoh Jane Akinyi

ABSTRACT
Recent studies show Trichoderma species are not only parasites of fungal plant pathogens but
also can enhance plant growth and development. Heavy applications of agrochemicals in soils in
Embu county due to dependence on inorganic fertilizers and pesticides have potential to cause
negative effects on environment leading to decrease of food production in agriculture. A study
was conducted to evaluate virulence efficacy of local Trichoderma isolates as Biocontrol Agent
(BCA) on soil pathogenic fungi. Isolates of Trichoderma koningii, Trichoderma asperellum,
Trichoderma atroviride, Trichoderma reesei, and Trichoderma harzianum from Embu soils were
evaluated for their ability to inhibit the mycelial growth of pathogenic fungi Fusarium
oxysporum f.sp. phaseoli., in culture. Trichoderma spp. were also evaluated for the suppression
of Fusarium oxysporum f.sp. phaseoli., under greenhouse condition. Trichoderma spp. were
further investigated for their ability to promote plant growth and development of maize and bean
seedlings in Embu County in Kenya. Subsequently, genetic characteristics of the five
Trichoderma isolates were analyzed to confirm bioefficacy activities in relation to their
molecular similarity.
Trichoderma isolates significantly (p < 0.01) reduced the mycelial growth of the pathogen.
Growth suppression by Trichoderma reesei against Fusarium oxysporum f. sp. Phaseoli., had the
highest effect in inhibition of mycelial growth (60.0%) with p-value (0.018), followed by
Trichoderma koningii (55.2%) with
mechanisms.
(p=0.014) deploying antibiosis and mycoparasitism
Differences were observed with treatment
of Trichoderma reesei combined
Manure recording the highest with seed emergence germination index of 1.88, followed by
Trichoderma koningii combined Fusarium oxysporum (1.86). The application of inoculum with
Trichoderma koningii combined Fusarium oxysporum (6.7%) and Trichoderma reesei combined
Manure (6.7%) gave the highest reduction in disease incidence of Fusarium wilt on bean plants.
Treatments with manure increased the shoot height by 36.6 mm followed by inoculation of
Trichoderma koningii + Manure (35.2) and Trichoderma koningii (34.7). Effects were highly
significant at p < 0,001 with f- value of 4.716. The highest rate of seedling emergence was 84%
for maize seeds coated with the Trichoderma inoculum and planted in soil amended with
manure. Similarly, differences were observed with Manure + Trichoderma treatment of 74.40%
and Manure (74.00%) recording the highest germination rates followed by both Trichoderma
treatments with both TSP/CAN and Mavuno (69.60%). This study demonstrated that local
isolates of Trichoderma reesei and Trichoderma koningii were identical in their biocontrol
characteristics as well as potential for use as biological control agents to protect bean plants from
Fusarium oxysporum f.sp. phaseoli.,
Keywords: Trichoderma, Biocontrol, Fusarium oxysporum.