Abstract:
Tomato (lycopersicon esculentum) is one of the most important vegetable crops belongs to the
family solanaceae ranking 8th in annual national production in Ethiopia. In spite of this, major
pests like, Phytopthora infestans, affect the production of tomatoes around the world. To achieve
profitable yields economically, producers intensify chemical treatments to control plant diseases
but indicate health risks to the consumers. As result, application of biological antagonists
against tomatoes disease reduces incidence and severity of the pathogen. Therefore, the aim of
the study is to assess the antagonistic potential of isolates of Trichoderma against the
Phytopthora infestans on the growth and yield of tomato plants. The 40 diseased plants samples
were collected from Dedo and Goma districts and analyzed in Jimma university. All the data
were subjected to one-way ANOVA at p ≤ 0.05. From 36 isolates, 18 were identified to be
Phytopthora infestans and from 103 isolates obtained from soil, 10 were Trichoderma spp. In
dual culture assay, the 3 days percentage of inhibition of pathogen by Trichoderma-Ju-TGDa-2,
Ju-TGDb-3, Ju-TDWc-2 and Ju-TGDb-2 varied from 10.2 to 15%, 38% to 43.4% in 6 days and
increased to 58 to 61.4% in 9 days. The non-volatile compounds of Trichoderma-Ju-TGDb-3, JuTDWc-2, Ju-TGDa-2, Ju-TGDb-2 and Ju-TGDb-1 inhibited with 63.9%, 60.9%, 57.7%, 44.4%
and 24%, respectively. The volatile compounds of the Trichoderma-Ju-TGDb-2, Ju-TDWc-2, JuTGDb-3 and Ju-TGDa-2 inhibition varied between 42.5 to 2.5 in 3 days, 63.5 to 34.7% in 5 days
and 64.1 to 35.8% in 6 days. In greenhouse, the shoot length, root length, fresh and dry weights
and yields of tomato plants were 78.7 cm, 28.21 cm, 104.11 g, 28.44 g, 15.96 g respectively. It is
concluded that the Trichoderma isolates Ju-TGDa-2, Ju-TGDb-3 and Ju-TDWc-2 are the most
promising biocontrol agent against the late blight as well as enhance the growth and reduce the
relative percent yield loss of tomato plants. It should be recommended that the potential isolates
should be further evaluated for their safety and the protocol of administration need to be
developed for field application by smallholder farmers.
