Efficacy of Ignite and Flexstar Tank Mixtures on Giant Ragweed and Common Lambsquarters

Control of giant ragweed and common lambsquarters, two commonly found broadleaf weeds in the Eastern corn‐belt, is erratic with glyphosate. Field experiments were conducted to determine the effects of Ignite and five rates of Flexstar alone or in combination on 8‐ to 12‐inch‐tall giant ragweed and 5‐ to 8‐inch‐tall common lambsquarters. At 21 days after treatment, an increase in the rate of Flexstar alone from 4 to 21 fl oz/acre increased the suppression of giant ragweed and common lambsquarters from 33 to 84% and 0 to 16%, respectively. Height reduction from applications of Ignite at 24 fl oz/acre alone or in tank mixtures with all rates of Flexstar was greater than 92% for giant ragweed, but only 70 to 87% for common lambsquarters. Ignite alone or tank mixed with Flexstar can be an effective management tool for control of glyphosate‐resistant giant ragweed in Liberty‐Link soybean, but not common lambsquarters. A pre‐emergence residual herbicide should be included to improve control of common lambsquarters.