effect of isolates of trichoderma harzianum, t. virens and bacillus subtilis for controlling heterodera schachtii in field conditions

in this survey, the effect of two commercial products trichodermin (trichoderma harzianum bi ) and subtilin (bacillus subtilis s) along with one strain of t. virens vm1 isolated from sugar beet farms of mashhad were used for controlling heterodera schachtii in field conditions. t. virens vm1 was formulated as two other commercial products. in this order, this strain was sub cultured on p.d.a. then, spores of each petridish was washed in 10 ml distilled water after 10 days and was mixed with talk powder for preparing the powder containing 107 propaguel/ g. the three products were applied as seed coating and dispersal in furrow with cucupit. an infested field to h. schachtii was selected in jolgeh rokh in torbat hydarieh area in razavi khorasan province and initial population of nematodes were detected. the experiment was conducted as randomized complete blok design with nine treatments and four replications in 2010 in field conditions. analysis of variance for the bio control potential of isolates, final population of nematodes, reproductive factor of beet cyst nematode, fresh root and leaves weight was carried out. the results revealed a significant difference (p < 0.05) between treatments and control according to duncan’s multiple range test. treatments t. virens vm1, separated from mashhad, decreased significantly (p < 0.05) the population of nematode at the rate of 52% and 51% in seed coating and dispersing in the furrow, respectively. the resistant check, paulina, decreased population of nematodes by 68% compared with the control. it seems two treatments that the mentioned could be used for decreasing population of nematode