Evaluation of the effectiveness of Trichoderma fungus isolates against root-knot nematodes under laboratory condition in Iraq

Abstract

To isolate and identify the indigenous species of the fungus Trichoderma spp. and to evaluate its pathogenicity against the knot nematod, Meloidogyne javanica. 25 random samples of  soil and roots infected by root-knot nematodes were collected from some fields and greenhouses of Solanaceae and Cucurbitaceae plants from eight agricultural sites in Wasit Governorate for the period from 5/11/2022 to 22/12/2022. The results of identification and characterization showed that 15 samples out of 25 samples contained the Trichoderma fungus, and by purification, it was obtained that 7 native isolates of the Trichoderma fungus belonging to four different species: T .harzianum, T.hamatum, Trichoderma sp₁, and Trichoderma sp₂ . The results also illustrated that a high efficiency of all Trichoderma fungus isolates studied in parasitizing nematode larvae and reducing the percentage the number of nematode larvae. The T.harzianum3(T6)  isolate was the most effective compared to the other isolates, as its parasitism rate reached 97%, with significant differences with all isolates, as noted. A clear decrease in the number of emerging larvae compared to the control treatment. The results showed that the isolates T.harzianum1 (T1) , T.harzianum2 (T3) , T.harzianum2 (T7) , had a high rate of parasitism, as the rates of parasitism for these isolates were 92.2%, 90.8%, and 90.4%, respectivelyrespectively.