Abstract:

The objective of this study was to determine the effect of different treatments times of aclonifen, which is used as pre- and post-emergence herbicide in the control of blackgrass [Alopecurus myosuroides Huds. (Poaceae)] on the critical concentration values resulting in 100% success. The plants of A. myosuroides were grown on pots under greenhouse conditions. In the study, to determine the herbicide contraction on the plant tissues accurately, 14C-aclonifen was added to the aclonifen suspension concentrate (SC) Challenge 600 and suggested dose (270 g e.m. da-1) was treated. The trials were initiated in march and april of 2011 and the treatments were applied the first (pre-emergence), 20th (early post-emergence) and 40th (later post-emergence) days. 10-day after each treatment, the symptoms were evaluated; and, the fresh and dry weights of the leaves were recovered. The aclonifen concentration on the fresh and dry leave samples were determined by the measuring the total radioactivity amount in dpm using liquid scintillation analyzer. The results of the trials indicated that the suggested doses of aclonifen critical concentration on the A. myosuroides leaves were: 1.58 ± 0.16 nmol/mg dry weight for pre-emergence; 3.04 ± 1.57 and 0.94 ± 0.81 nmol/mg dry weight for early and late post-emergence, respectively. It was also determined that the treatment of aclonifen with suggested dose when applied either as pre-emerge or as early post emergence until the plants reach 1-2 leaf stage before emergence or until 1-2 leaf stage result in 100% control; however, the treatments applied after 3-4 leaf stage are not successful although they result in delays of plant development.

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