Evaluation of antagonistic activities of <i>trichoderma</i> isolates against <i>Fusarium wilt</i> (<i>Fusarium oxysporum</i>) of tomato (<i>Lycopersicon esculentum</i> Mill.) isolates

Abstract

The study was initiated with the objective of controlling tomato wilt disease (Fusarium oxysporum) using Trichoderma isolates as biocontrol agents. F. oxysporum was isolated from diseased tomato plants grown in five selected kebeles of Dugda Bora and Adami Tulu Jido-Kombolcha woredas of the Central Rift Valley (CRV) region of Ethiopia. The pathogenicity of F. oxysporum was determined on three different tomato varieties namely Cochoro, Miya and Fetane that were grown in 20 cm plastic pots containing 3 kg of autoclaved soil under the greenhouse. The antagonistic effect of Trichoderma isolates against the test pathogen was tested both in vitro and in vivo conditions. From the three tomato varieties, Miya was more susceptible to F. oxysporum infection than both Cochoro and Fetane varieties. The antagonistic effects of Trichoderma isolates on the mycelial growth of the test pathogens, AUT9, AUT 8 and AUT10, showed 66%, 61% and 58% inhibition, respectively, on the mycelial growth of F. oxysporum isolate. All Trichoderma isolates achieved maximum mycelial growth at 25°C and minimum mycelial growth at 15°C. From the current comparative in vivo and in vitro (green house) studies it is evident that the most effective antagonist of the Trichoderma isolates to F. oxysporum was AUT9 and the most resistant tomato variety was Fetane.

Keywords: Antagonism, Antibiosis, Pathogen, Pesticide, Resistance, Symptom