Significance of Atrazine as a Tank-Mix Partner with Tembotrione

Abstract

Manufacturers of several POST corn herbicides recommend tank-mixing their herbicides with atrazine to improve performance; however, future regulatory changes may place greater restrictions on atrazine use and limit its availability to growers. Our research objectives were to quantify the effects of tank-mixing atrazine with tembotrione compared to tembotrione alone on (1) weed control, (2) variability in weed control, and (3) sweet corn yield components and yield variability. Field studies were conducted for 2 yr each in Illinois, Oregon, Washington, and Ontario, Canada. Tembotrione at 31 g ha−1 was applied alone and with atrazine at 370 g ha−1 POST at the four- to five-collar stage of corn. The predominant weed species observed in the experiment were common to corn production, including large crabgrass, wild-proso millet, common lambsquarters, and velvetleaf. For nearly every weed species and species group, the addition of atrazine improved tembotrione performance by increasing mean levels of weed control 3 to 45% at 2 wk after treatment. Adding atrazine reduced variation (i.e., standard deviation) in control of the weed community by 45%. Sweet corn ear number and ear mass were 9 and 13% higher, respectively, and less variable when atrazine was applied with tembotrione, compared to tembotrione alone. Additional restrictions or the complete loss of atrazine for use in corn will necessitate major changes in sweet corn weed management systems.

Control of glyphosate-resistant giant ragweed (Ambrosia trifida L.) with premix of iodosulfuron/thiencarbazone applied alone or in tank mixtures in no-till corn (Zea mays L.)

“…14 and 28 d after POST (DAPOST)(Table 3). Similarly,Williams et al (2011) reported 77 to 95% control of giant ragweed in sweet corn with a tank-mixture of tembotrione and atrazine. A POST application of tembotrione plus atrazine was more effective for control of giant ragweed compared with a PRE application of isoxaflutole /thiencarbazone plus atrazine.…”

Interaction of PS II‐ and HPPD‐Inhibiting Herbicides for Control of Palmer Amaranth Resistant to Both Herbicide Sites of Action

“…Jhala et al (2014) also reported similar (96-98%) control of the same Palmer amaranth biotype from Nebraska with tembotrione applied alone or tank mixed with atrazine. In contrast, Stephenson et al (2015) and Williams et al (2011) reported 95 to 97% control of susceptible Palmer amaranth and redroot pigweed with tembotrione tank mixed with atrazine compared to tembotrione applied alone (80-91%). Palmer amaranth control was reduced at 28 DAT due to new seedling emergence because of its extended emergence pattern; therefore, tank-mixing atrazine with topramezone or tembotrione did not improve control compared to when applied alone at 28 DAT, with the exception of tank mixing topramezone at 22 g ha -1 with atrazine at 2240 g ha -1 .…”

HPPD-Inhibiting Herbicides Alone or in Tank-Mix with Atrazine in Elephant Grass

“…The percentage of weed control, at 30 DAT, ranged from 77% (mesotrione: 0.072 + 0.5% oil) to 85% (atrazine + mesotrione: 1.25 + 0.072 + 0.5% oil). Williams et al (2011) emphasized the importance of using atrazine in a tank-mix with other herbicides due to the increase in spectrum of weed control. The authors observed that in tank mixing of atrazine with HPPD-inhibiting herbicides provided increases in the number and weight of ears of sweet corn of 9% and 13%, respectively, when compared to these herbicides applied alone.…”