comparison of efficacy in split and single dose application of mesosulfuron methyl+iodosulfuron methyl sodium on wild oat (avena ludoviciana)

nowadays herbicide reduction and different approaches leading to this goal like split application have been brought to attention. two green house experiments were carried out to investigate the efficiency of single and split application of mesosulfuron-methy+iodosulfuron methyl to control wild oat (avena ludoviciana). the influence of applications intervals and the ratios of the two applications doses were studied. analysis of the data performed based on two statistical approaches: comparison between ed90 of the treatments and joint action model. the study revealed that both single and split application efficacy decreased as application timing was delayed but this reduction was more highlighted at single spray. 75:25 ratio approximately at all application timing showed more activity to control wild oat. but considering joint action model, 50:50 ratio was the only rate that showed antagonism at late growth stages of wild oat (spray 7 and 14 days after 2 leaf stage). there was an additive reaction for both 50:50 and 75:25 ratios at early growth stage of wild oat (spray 3 days after 2 leaf stage). totally it could be concluded that efficacy of split application of mesosulfuron-methy+iodosulfuron methyl was more potent than that of the single one.