Investigating the Effectiveness of Some Registered Fungicides in Control of Wheat Tan Spot

Tan spot disease incited by Pyrenophora tritici-repentis, is an important disease of wheat throughout the world, including Iran. The disease inflicts considerable losses to the crop in the epidemic conditions. Application of fungicides is a quick method for control of the disease in epidemic years. In this study, the effect of some registered fungicides was evaluated on growth inhibition of the causal agent as in vitro, and also for control of the disease in greenhouse and field conditions on a susceptible wheat line (N-80-19). The experimental design was carried out as completely randomized in in vitro condition and as split plot in greenhouse and field conditions with 3 replications. Main plots were included the fungicides Cyproconazole, Cyproconazoleপ�睚츩 (Altocombi), Flusilazoleপ�睚츩 (Alert), Iprodioneপ�睚츩 (Rovral T-S), Propiconazole, Tebuconazole, Carbendazim and Benomyl), and sub-plots were consisted of the spraying times (flag leaf, head appearance and flag leafꖩ appearance stages). The treatments were evaluated by recording the infection index, 10 days after the last spraying simultaneously with disease development on control plots. The grain yield was also calculated after wheat harvesting. The results demonstrated Rovral T-S (73.83%), Altocombi (71.92%) and Alert (69.42%) had maximum in vitro growth inhibition of the fungus. The three fungicides showed considerable advantages on reduction of infection index and increase of yield in greenhouse and field tests, compared to other fungicides. For infection index, no-significant difference was recorded among spraying times. The highest thousand grain weight was respectively obtained by spraying at flag leaf head appearance (increasing 10.11 and 9.94 grams), flag leaf (increasing 9.26 and 9.18 grams) and head appearance stages (increasing 9.15 and 8.68 grams, respectively, for greenhouse and field), compared to their control.