Temperature Effect on Barban Phytotoxicity

Abstract

The phytotoxicity of barban (4-chloro-2-butynylm-chlorocarbanilate) applied 14 days after emergence to wheat(Triticum aestivumL. ‘Waldron’) and wild oat(Avena fatuaL.), at constant, fluctuating or alternating day-night temperatures was determined in controlled environmental chambers. Wheat and wild oat susceptibility to barban increased as post-treatment temperature decreased. Maximum barban selectivity for wild oat in wheat occurred with a constant 18 C or an alternating 18 C day and 10 C night post-treatment temperature. At least three days of 10 C immediately following barban application were necessary to cause wheat injury. However, two days at 29 C immediately after barban application in an otherwise 10 C post-treatment regime reduced wheat injury. Further, a night temperature lower than the day temperature after barban application increased wild oat control but did not correspondingly increase wheat injury compared to the constant temperature treatments.