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Five fungicides, with active ingredients azoxystrobin, imazalil, thiabendazole, azoxystrobin + difenoconazole and fludioxonil + difenoconazole, were tested against two isolates of Fusarium solani and two isolates of F. oxysporum, causing potato dry rot in Mashhad region. PDA media amended with the fungicides significantly inhibited the mycelia growth of all Fusarium isolates incubated at 25 °C for 7 days; however only Imazalil and Thiabendazole completely stopped the mycelia growth of all fungal isolates even at their lower concentration (40 and 5ppm respectively). The mean penetration of F. solani FPO-67 and F. oxysporum FPO-39, the more virulent of the four isolates, after 21 days of incubation at 25-27 °C indicated that imazalil and thiabendazole at concentrations of 1.5 and 2/1000, completely inhibited the penetration of F. oxysporum FPO-39 into potato tubers, but in the case of F. solani FPO-67 all treatments (1, 1.5 and 2/1000) significantly reduced the development of dry rot compared to untreated control. In natural condition, tuber treatment with Imazalil and Thiabendazole (2/1000), prior storage, reduced F. solani FPO-67 development by 68 and 71.69% respectively. According to the results, these fungicides could play a role in integrated pest management against tuber-borne fungal pathogens.
 
 

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Combinations of traditional fungicides and natural compounds have the potential to produce more effective antifungal activity at sufficiently low concentrations. The potential fungicidal activity of binary mixtures comprising Coriandrum sativum and Foeniculum vulgare essential oils (E.O.s), as well as the two azole fungicides, Difenoconazole and Tebuconazole, were examined employing the n.n design. The concentration addition (C.A.) and independent action (I.A.) models were used to analyze the combined effects of the mixtures. In most mixtures, the essential oil enhanced the fungicidal activity of the azole fungicides. Mixtures containing Tebuconazole and F. vulgare exhibited a strong synergism, with an EC₅₀ value of 43.12 for Mix. 9. The model deviation ratio (M.D.R.) for the tested mixtures ranged from 0.61 to 13.61, indicating the absence of antagonistic interaction among the mixtures components. It was observed that the I.A. model tended to underestimate the fungicidal activity, while the C.A. model provided a more accurate prediction. Further studies are required to investigate the primary natural products in these essential oils responsible for the synergistic effect on the azole fungicides.