We have received reports from cowpea and peanut fields of beet armyworm surviving applications of chlorantraniliprole (Coragen, Prevathon, Vantacor, Besiege). While this does not mean we have resistance, it is an indication that we should be cautious with applications of these products and definitely switch chemistry if you suspect a field failure with the first application. The cowpea field in question was treated multiple times with products containing chlorantraniliprole (Besiege and Coragen) and still had high populations of beet armyworm larvae. We collected 50 larvae and held them on foliage collected from the field and 43 were still healthy three days later.
Does this mean to avoid applications of products containing chlorantraniliprole? NO. We do not know if this is truly a resistance problem, and if it is we do not know how widespread it may be. Simply be aware that this MAY be a problem and if you suspect a control failure switch chemistry (away from any Group 28 insecticide) for any repeat applications.