Weed control of wheat by pre-plant and preemergence herbicides.

This experiment was conducted from 2004 to 2005 at the Safiabad agricultural research center and nature resourses of Dezful Ahvaz,Gorgan and zarghan to evaluate the efficacy of soil applied herbicides in controlling weeds of wheat field. The experimental design was a randomized complete block design with split plot arrangement of treatments. Post emergence application of the mixture of tribenuron + clodinafop was as main plot and application of soil applied herbicides was as subplot. Main plots consisted of application of the mixture of tribenuron + clodinafop at (15 g + 0.64 kg), (7,5 g + 0.32 kg) ai fha and without application of the mixture of tribenuron + clodinafop. Subplots consisted of preplant application of metribuzin at 0.7 and 0.52 kg ai /ha, respectively, trifluralin at 1.2 kg ai /Da, EPTC 3.2 kg ai /ha, trebutryn + triasulfuron at 250 g fha, preemergence application of isoproturon + diflufenican at 1.38 kg ai /ha, preplant application of sulfosulfuron at 20 g ai /ha and weedy check. The wheat in Treflan and. Eradican treatments was emerged 3-5 days later than other herbicides and after the first irrigathion. The expriment of treflan and Eradican and Sencor's herbicides had negative effect on the height of wheat and the final minimum height of wheat had related to Treflan's treatment. The maxium height of wheat is related to Panter and Logran' s herbicides. The most negative effect on wheat is related to Treflan's treatment(about 22%) and after that Eradican (12%) and Sencor 1kg/h (7%) have most negative effect on wheat. Seneor's herbicides(0/5) among other herbicides have low negative effect on wheat. The Panter's herbicides damaged wheat about 3%(by whitness of leaf) that this damage remove soon. The other herbicides have not negative effect on wheat. The highest 1000 grain weight is related to Panter and the Apiros has low 1000 grain weight, that this one in comparison with control treatmentsand Treflan were in the same statistical group.Among the pre¬ plant's herbicides, Panter's herbicides produced highest grain yield, that in comparison with control treatment increased yield(about 7%). When this treatment applied with complete doze of pre-plant herbicides increased the yield about 4% that show the Panter lonely can produce the highest yield.