study of antifungal activity of plant extracts of catmint, tobacco and thyme on tobacco pathogens fungal.

the experiment was done in a factorial design based on completely randomized with three factors and five replications in vitro. the first factors, plant extract (nine plant species), the second factor, solvent (5 solvent) and the third factor, concentration (3 concentration) were considered. in pot condition, the experiment was carried out in factorial based on completely randomized design with 18 treatments and three replications in tirtash reaserch and education center in 2013 year. this study, the first factor including: three plant extracts (catmint, tobacco and thyme), the second factor, three concentration (0.5, 1 and 2 in 1000) and the third factor, treatment application of method two (spray and drench) were considered. results of study of antifungal activity of different concentration of extracts indicated that crude extracts of catmint, tobacco, thyme, fennel, hyssop and badrashbi have remarkable antifungal activity on fungi examined in this study. methanol was the best solvent to extract antifungal compounds. the maximum inhibitory concentration of each extracts was determined 2000 ppm. the results of analysis variance showed that the effect of plant extracts on control percent of soilborne pathogens fungal of tobacco was significant in %1 level. interaction of plant extracts in concentration and concentration in treatment application method and also plant extracts in concentration and treatment application on disease control percent was significant in %1 level. mean comparison of treatments showed that 2/1000 extracts concentration of catmit and tobacco with 80 and 75 percent control was the best treatment.