Interaction Effects of Atrazine and CDAA, Linuron, Amiben, or Trifluralin on Soybean Growth1

Abstract Growth chamber experiments were conducted to study the influence of atrazine, CDAA, linuron, amiben, trifluralin, and combinations of atrazine with these herbicides on the dry matter produced by two varieties of soybeans. Sublethal atrazine treatments did not significantly depress soybean growth as compared to the control. The effect of atrazine in combination with CDAA or linuron was not significant. When damping off organisms were not controlled, severe injury to soybeans occurred in treatments containing amiben or trifluralin at 4.5 ppmw. Sublethal amounts of atrazine appeared to overcome this injury. When seeds were treated with fungicide, the growth of soybean seedlings was depressed by treatments containing combinations of trifluralin and atrazine in proportiont to the amount of atrazine present. Combinations of atrazine and amiben gave growth responses similar to those observed in the earlier experiments, except that pathogen injury was inhibited by the fungicide.