Biological Control of Sugar Beet Cyst Forming Nematode with Trichoderma Under In Vitro and Green House Condition

Sugar beet cyst forming nematode (Heterodera schachtii) is one of the most important pathogens of the sugar beet in Iran. For biological control of Heterodera schachtii, 10 isolates of Trichoderma related to two species T. harzianum and T. virens were examined in laboratory and green house on eggs and cysts for two years. Results obtained from the laboratory assay showed that isolates of Trichoderma parasitized 60% eggs on average. Among them two isolates T. harzianum Bi and T. virens VM1with % 76.18 and %72.55 parasitism, respectively, showed more efficiency compared with the control. In green house, experiments were carried out in autoclaved and non autoclaved soils (field soils) separately with 12 treatments and 3 replications including non infested control (using Ragbi nematicide in field soils experiment), and infested control treated with isolates of Trichoderma using Randomized Complete Design. Then analysis of variance for the bio-control potential of isolates, final population of nematode, fresh and dry root weight, fresh and dry leaves weight inoculated with isolates of Trichoderma was carried out. The results revealed a significant difference (P<0.05) between treatments and control according to Duncan,s Multiple Range Test. T. harzianum Bi and T. virens VM1 decreased population of nematodes, and increased yield in autoclaved and field soils. In autoclaved soils, the two isolates (T. harzianum Bi and T. virens VM1) decreased population of nematodes by %76.68 and %72.65, respectively compared with the control. The Ragbi nematicide, T. harzianum Bi and T. virens VM1 decreased population of nematodes by %81.65, %75.15 and %72.85, respectively compared with the control in field soils experiments.