Efficacy of Some Trichoderma Species Against White Rot of Garlic Caused by Sclerotium cepivorum

White rot disease caused by Sclerotium cepivorum is a major yield reducing fungal disease of Allium sp. found throughout the world, including Europe, Asia, Africa, America, Australia, New Zealand and Turkey. Control measure for this disease is costly and contaminates the environment, harms non-target organisms. Moreover, the pathogen is soilborne and produces abundant sclerotia which can remain dormant for more than 15-20 years. Because of this, chemical control strategy is not quite effective against the disease. So there is a necessity of alternative methods in the struggle against plant diseases. Trichoderma is known as the most widely used antagonists in biological control. The effect of some Trichoderma species (Trichoderma harzianum, T. virens, T. croceum, T. neokoningii, T. viride, T. spirale, T. atroviride, T. tomentosum, T. gamsii, T. asperellum, T. inhamatum, T. strigosum) were studied both in vitro and in vivo conditions. Trichoderma species and Sclerotium cepivorum placed in PDA medium by duel culture techniques and incubated at 22 ± 240C. Results showed that the most effective isolates were T. harzianum LO52, T. virens KB31, T. gamsii VG47, T. strigosum LO43, T.tomentosum VG2, T. asperellum TZ17 and T. viride VG18, respectively. The experiment was conduct with selected Trichoderma isolates and S. cepivorum as a pot study in greenhouse. The design of the experiment was completely randomised. There were 9 treatments with four replicates. Results showed that almost all Trichoderma isolates caused in different rates reductions (21.42 to 64.28 %) in the incidence of garlic white rot disease