Shiraz University Iran Agricultural Research 1013-9885 29 2 2011 03 20 Antagonistic Activities of Trichoderma spp. on Phytophthora Root Rot of Sugar Beet فعالیت آنتاگونیستی گونه های تریکودرما روی پوسیدگی فیتوفتورایی ریشه ی چغندر قند 21 38 134 10.22099/iar.2011.134 EN G. MOAYEDI Department of Plant Protection, College of Agriculture, Shiraz University, Shiraz, I.R. Iran R. MOSTOWFIZADEH-GHALAMFARSA Department of Plant Protection, College of Agriculture, Shiraz University, Shiraz, I.R. Iran Journal Article 2012 06 26 <em>Trichoderma</em> species are among important antagonists of plant pathogenic fungi. The main purpose of this study was to evaluate the biocontrol potential of native<em> Trichoderma </em>spp. isolates from sugar beet fields against <em>Phytophthora drechsleri</em> and <em>P. cryptogea</em>,<em> </em>the causal agents of Phytophthora root rot of sugar beet. During 2007–08, 85 isolates of <em>Trichoderma</em> spp. from sugar beet fields in eight parts of Fars province, Iran were isolated. Based on morphological and physiological characteristics, eight species could be distinguished: <em>T.</em><em> asperellum</em>,<em> T. atroviride</em>, <em>T. brevicompactum</em>, <em>T. harzianum</em>,<em> T. longibrachiatum</em>,<em> T. spirale</em>,<em> T. tomentosum</em> and<em> T. virens</em>.<em> </em>Their antagonistic activities  including competition, colonization and antibiosis against <em>Phytophthora </em>isolates both <em>in vitro</em> and <em>in planta </em>were investigated. Different species and even different isolates of one species differed in their antagonistic capacities. High competitive abilities were shown by <em>T. asperellum</em>, <em>T. atroviride</em>, <em>T. harzianum</em> and <em>T. virens</em> in pre colonized plates, and by the former three species in dual cultures. <em>T. harzianum</em> and <em>T. atroviride</em> efficiently colonized both species of <em>Phytophthor</em><em>a</em>. <em>T. asperellum</em> Ksh2, <em>T. virens</em> DB6r, <em>T. virens</em> DB2 and <em>T. virens</em> DB3 and <em>T. harzianum</em> MS3 gave the highest growth inhibition. In <em>in planta</em> experiments, <em>T. harzianum</em> MS3 and FG4 and <em>T. virens</em> DB6r were the most efficient in suppressing root rot of sugar beet seedlings. Our results suggest that <em>T. harzianum</em> MS3 is the best native candidate for the biocontrol of this disease. https://iar.shirazu.ac.ir/article_134_a9aa0fe6b8c28c9c4fe2f87121c5a323.pdf