Differential Response of Maize Inbreds to Bentazon and Other Herbicides

One field and two greenhouse experiments were conducted to determine the reaction of various maize (Zea mays L.) inbreds and single crosses to four herbicide treatments (atrazine, atrazine plus tridiphane, bentazon, metolachlor) relative to a nontreated control. All herbicides except metolachlor, which was used preemergence, were applied early postemergence with a nonphytotoxic crop oil at 1% carrier volume. Of significant importance is the discovery of maize susceptibility to bentazon and its inheritance. We suggest that the symbol, ben, be assigned to the recessive gene that causes this susceptibility. In the greenhouse, inbreds were more tolerant to atrazine and bentazon than other herbicide treatments. Tridiphane increased atrazine activity and reduced dry plant weight of inbreds on the average by 19%. None of the single crosses was significantly susceptible to atrazine. All inbreds and single crosses were sensitive to metolachlor in the greenhouse, as shown by the 49 and 35% reduction in dry weight, respectively. Information from these experiments can be useful in identifying sources of tolerance and susceptibility to the tested herbicides for programs in conventional maize breeding, weed control, and molecular engineering.