author(s)
Chihani Hammas Noura, Regaieg Hajer, Larayedh Asma, Hajji Hedfi Lobna and Horrigue-Raouani Najet

abstract
In Tunisia, apples have an important place in the fruit sector. The root-lesion nematode is a major pest of pome due to the significant root damage it causes. In this study, we investigated under laboratory and greenhouse conditions the effect of Verticillium leptobactrum isolate (HR1) against Pratylenchus vulnus associated to three-apple rootstock (MM106, MM111 and Ba29). In vitro study, five concentration of V. leptobactrum were tested for nematicidal activity against P.vulnus. The microscopic observation of treated nematodes showed serious alterations caused by the fungal filtrate. The greatest activity was observed at 10 to 75% of filtrate dilutions. In greenhouse experiment, the reproduction of the root-lesion nematode and the parameters of growth of three-apple rootstock were evaluated. For the plants of Ba29, V. leptobactrum increased total weight and diameter but had no significant effect on the growth parameters of other rootstock (MM106 and MM111). Plants inoculated with the nematophagous fungi generally showed important reduction in the population of P. vulnus either in the soil or in roots than plants inoculated with chemical treatment (Mocap) and non-treated plants. The nematode multiplication rate differs significantly only for the MM106 rootstock.