To study resistance of winter wild oat (Avena ludoviciana) to clodinafop propargyl (Topik), diclofop methyl (Illoxan), and fenoxaprop p ethyl (Puma super) herbicides in wheat fields of Khuzestan province, seedlings of 46 wild oat population were collected from farmers' fields at seven sites of the province including Ahvaz, Andimeshk, Shush, Shushtar, Ramhormoz, Susangerd (Dashte Azadegan), and Dezful. The seed samples were screened in the greenhouse College of Agriculture, Ferdowsi University of Mashhad, in 2005. Clodinafop propargyl, diclofop methyl, and fenoxaprop p ethyl, were applied at recommended rates of 64, 900, and 75 g ai ha-1, respectively. Each experiment was laid out in a completely randomized design with 3 replications. Visual phytotoxicity rating, the percentage of survived plants, and relative dry weight (percentage of control) were used to evaluate seed population response to herbicide treatment. Results showed that moderate but statistically significant variation in winter wild oat resistance existed amongpopulations from different sites and among populations in wheat field of the same. Seed populations collected from Shushtar and Ramhormoz showed higher resistance to all three herbicides. It could be concluded that some winter wild oat seed populations collected from Khuzestan wheat fields are suspected to herbicide resistance.

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