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Abstract
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Wild barley has invaded wheat fields ever since flamprop-isopropyl was outdated in Iran. Newly developed herbicides such as sulfosulfuron or sulfosulfuron plus metsulfuron-methyl can control it at higher than recommended dosages but causing significant wheat injury. Hence, two dose-response experiments were conducted to evaluate their efficacy when tank-mixed with thirteen different vegetable oils at the Ferdowsi University of Mashhad, Iran during 2013. Moreover, a wheat cultivar (Gaskogen) was also treated with effective dose 90% (ED90) of both herbicides (21.44 g a.i. of sulfosulfuron ha-1 and 41.95 g a.i. of sulfosulfuron plus metsulfuron-methyl ha-1) with and without each vegetable oil to check selectivity. Averaged over vegetable oils, the effective dose 50% (ED50) was decreased 2.6- and 2.0-fold with sulfosulfuron and sulfosulfuron plus metsulfuron-methyl, respectively. Among evaluated the vegetable oils, both cottonseed and coconut oil were the best ones to enhance the efficacy of both herbicides. The castor oil had the least effect. A negative correlation was observed between the efficiency of vegetable oils and its unsaturated/saturated fatty acids ratio. The phytotoxic effect on wheat did not observe when they were applied with and without vegetable oils.
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