Herbicide application is a common tool used to manage invasive annual grasses (IAGs), such as cheatgrass, ventanata and medusahead. The commonly used herbicides used are indaziflam and imazapic. Our goal with this module is to provide information about these herbicides and how they can be a tool for managing IAGs. 

Indaziflam is a root growth-inhibiting herbicide that is rapidly being adopted to manage invasive annual grasses across rangelands of the western U.S. Indaziflam is a pre-emergent herbicide labeled for use in non-crop areas, perennial crops, turf, and grazed rangelands that disrupts the root elongation process (Brabham et al. 2014; Brosnan et al. 2011; Alonso et al. 2011; Sebastian et al. 2017b). Indaziflam is non-selective chemically, but its soil-binding properties largely confine it to the top several centimeters of the soil profile, making it only active to roots in that shallow soil zone (Alonso et al. 2011; Gonzalez-Delgado and Shukla 2020). Indaziflam movement deeper into soils may be affected by soil properties (i.e. clay and organic matter content and soil bulk density/porosity) and precipitation. Indaziflam was detected one year following application at depths of 7-15 cm in an Arizona pecan orchard (Gonzalez-Delgado et al. 2015). Indaziflam has a half-life of 150 days (US EPA 2010), but its apparent effects on vegetation when applied at field-use rates last much longer (please see below).