Efficiency of herbicide as affected by field environmental temperature and moisture in wheat

In order to evaluate the efficacy of mesosulfuron + iodosulfuron + diflufenican (Othello OD( herbicide doses under temperature and soil moisture conditions in the control of wheat weeds, field experiments were carried out in Fars and Alborz provinces during 2017 to 2018. Treatments included spraying at different times after irrigation (different soil moisture conditions) as main plots in three levels (2 and 7 days after irrigation and 1 day before next irrigation), dose of herbicide as a subplot at 6 levels (0, 25, 50, 75, 100 and 125% of recommended dose), and spraying day time as sub-sub plots at two levels (7-8 am, and 11-12am). The results showed that in the condition that moisture had provided after spraying, reduced doses of these herbicides were more effective in reducing the dry weight of broad leaves weeds than other conditions. 33, 66 and 99 g ai/ha herbicide doses (25, 50 and 75% of recommended concentration), especially in 2 days after irrigation and 1 day before irrigation tratments, weed dry weight of grass weeds had more difference than 7 days after irrigation conditions, compared to control treatment. Under normal moisture conditions (field capacity), the reduced concentrations were more efficient in controlling the weeds and the higher moisture stress resulted in the lower efficiency of the reduced concentrations.