Utilizing Postmergence Metribuzin Tolerance in the Management of Weeds in Early planted soybean and Characterizing Metribuzin Persistence in the Soil

Abstract/Summary: Metribuzin is becoming an increasingly popular herbicide in soybean produc on systems due to the emerging resistance of weeds to glyphosate, glufosinate, synthe c auxins and PPO- inhibitors. However, many producers are limited in their ability to apply metribuzin because it can only be applied as a preemergence (PRE) herbicide in soybean and some soybean varie es are sensi ve to metribuzin, causing heavy injury to suscep ble varie es if metribuzin is applied. With this project, we hope to expand the use of metribuzin in early- planted soybean and characterize the decrease of metribuzin concentra on in the soil. Due to the increasing trend early plan ng in soybean, it is impera ve that metribuzin soil dynamics are inves gated so that more op ons such as an addi onal postemergence (POST) can be explored to keep metribuzin at e?ec ve levels in the soil. Due to the fact that problema c pigweeds can germinate all the way through July, metribuzin used as a PRE in early-planted soybean is unlikely to last throughout the season, underpinning the importance of this work. Thus, in this project we aim to i) examine the dynamics of metribuzin in the soil with regular PRE treatments, PRE treatments in early-planted soybean and PRE with an addi onal POST treatment in early-planted soybean, ii) assess the impact of PRE and PRE with an addi onal POST metribuzin on weed control and soybean yield iii) con nue developing high- yielding, metribuzin-tolerant breeding lines stacking various sources of tolerance and iv) determine the impacts of metribuzin applica ons on key soil microbial func ons (i.e., nitrogen ?xa on).