ارزیابی توانایی گونه های Trichoderma harzianum و T. viride در کنترل بیولوژیک Fusarium oxysporum f.sp. dianthi

Vascular wilt caused by Fusarium oxysporum f.sp. dianthi is one of the most important diseases of ornamental carnation (Dianthus caryophyllus L.) which is considered as one of the limiting factors for its cultivation in most countries producing and exporting this flower. So far, the biocontrol effects of Trichoderma spp. on many fungal pathogens have been proven. For this study, random sampling collected 105 isolates from greenhouses in Tehran, Khuzestan, Fars, Kerman and Markazi provinces. From these collected isolates, 96 isolates were identified as Fusarium oxysporum f.sp. dianthi. After identification and confirmation by RFLP molecular method and pathogenicity test on vascular wilt sensitive cultivar (Rendezvous); they were used for further study. Ten isolates of Trichoderma viride and ten isolates of Trichoderma harzianum were collected from the rhizosphere of healthy carnation of the same greenhouses. After final confirmation of these isolates by RAPD molecular method, their antagonistic ability against this pathogen was tested in dual-culture method, volatile compounds test and CSA (Competitive Saprophytic Ability) test. The antagonistic range of these isolates were determined as 18% to 58% in dual-culture test, 9.3% to 67.5% in volatile compounds test and between 18.1% and 78.2% in CSA test. In all tests, Th1 and Tv5 isolates demonstrated the highest and the lowest antagonistic abilities against pathogen, respectively. Ten isolates of antagonists were used to evaluate the antagonistic effect for greenhouse experiments by inoculation with 106 suspension in sterile soil. Disease severity index was assessed on carnation cuttings during 70 days after treatment. Isolates Th1, Th7 and Th2 showed the greatest effect in controlling this disease compared to control and other antagonist isolates, respectively. The results of this study showed that Thrichoderma spp., especially Th1, Th7 and Th2 isolates can be used as an alternative or in combination with other control measures in the management of this disease.