Isolation of antagonistic fungi from tea plantation and study of their impact on tea root lesion nematode Pratylenchus loosi in laboratory

Tea root lesion nematode, (Pratylenchus loosi) is currently considered as the most important damage-causing agent in the most tea-producing countries including Iran. In order to use antagonistic fungi for biological control of this nematode, samples of soil and tea roots were collected during the spring and summer of 2013 in tea plantation of Guilan and Mazandaran provinces. Different fungi were isolated and identified from collected soil samples and or parasitic nematodes. These isolates included Paecilomyces lilacinus (isolates T1, N1, N3), Fusarium culmorum, F. graminearum, Cladosporium sp. and Trichoderma harzianum (isolates T1, T2, T3). Pathogenicity tests of these fungi on nematode were conducted on 1.5% water agar and mortality rate of Juvenile and adult nematodes were determined at three different periods of 48, 72 and 168 hours. Among the 11 tested isolates, the isolate of P. lilacinus (T1) with causing 64% mortality of juveniles and 29% the adults and also the isolate of P. lilacinus (N1)with having 47% mortality rate in juveniles and 24% in adults after 168 hours, had the highest mortality rate compared with other fungi. Also in this study, T. harzianum fungus was a very weak biocontrol agent compared with other isolates. The overall results showed that P. lilacinus have high potential to control tea root lesion nematode.