: Investigation on various methods of control for two serious weeds (Amaranthus retroflexus and Chenopodium album) in potatoes

To investigate of various methods of control for Amaranthus retroflexus and Chenopodium album in potato ( Solanum tuberosum var. Agriya ) a study was conducted in during 1383 _ 1384 in Semnan agriculthural research center. Experimental design was randomized complete block design with spilt-plot arrangement of 12 treatments and 3 replications. Main plot contained cultivation treatments at three levels including : 1- application of sweep cultivator 35 days after planting 2- application of sweep cultivator 35 and 55 days after planting 3- control without cultivation. Subplot contained herbicide treatments at four levels including : 1- Treflan (Trifluralin) EC 48% at 2 lit/ha preplant and soil incorporated , 2- Gramoxone (Paraquat) at 3 lit/ha before potato emergence , 3- Sencor (Metribuzin) DF 75% at 750 gr/ha before potato emergence , 4-control without herbicide. Each subplot with density 6 pl/m2 had six planting rows and 10 m length. The results showed that there were no significant difference between herbicide treatments for the number of weeds in 10 days after herbicides application. At the end of growth season the best controlling effect was observed for sencor and treflan herbicids which was significantly differed from gramoxone and no herbicide treatments. Although cultivation caused a significant decrease in the number of these two weeds ( at the level of 5%) in proportion to non cultivated treatment, there were no significant different between one and two times cultivation treatments. The results showed that the most controlling effect on these two weeds was for the sencor and treflan with one and two times cultivation and the least effect was for one and two times cultivation without herbicide application. Herbicide treatment showed a different effect on the yield of potato, in a way that the highest yield was obtaind with sencor, while the effect of cultivation treatments on the yield was similar to that of number of weeds. The analysis of multiple effects of herbicide and cultivationon the yield showed thah the highest yield was for the sencor with one and two times cultivation and the lowest yield was for the no herbicide and no cultivation treatment.