Evaluation of Trichoderma as a biocontrol agent for Rosellinia necatrix

Different isolates of Trichoderma harzianum and Trichoderma hamatum were isolated from naturally infected roots of Rosellinia necatrix. T. harzianum and T. hamatum isolates overgrew cultures of R. necatrix placed simultaneously in petri dishes. Relative levels of R. necatrix population were assessed by the avocado leaf colonization method. T. harzianum isolate T-8, significantly reduced R. necatrix colonization of avocado leaves in comparison to other isolates in artificially and naturally infested soils. R. necatrix inoculum decreased steadily over 4 and 6 week periods in artificially inoculated soil and naturally infested soil respectively when isolate T-8 was applied, to a point where no R. necatrix could be recovered. Disease incidence of almond seedlings was significantly reduced when isolate T-8 was added to naturally infested En-Zurim soil.