Little seed canary grass resistance to sulfonyl-urea herbicides and its possible management with pendimethalin

In this study, response of 20 Phalaris minor Retz. (little seed canary grass) populations against sulfosulfuron and its ready-mix formulation sulfosulfuron + metsulfuron and mesosulfuron + iodosulfuron was studied. Out of 20 populations, 12 showed high resistance, 8 showed medium resitance and none were susceptible to sulfosulfuron (25 g/ha). GR₅₀ value was in the range of 30–110 g/ha in P minor populations tested. In wheat, it was more than 200 g/ha. Eleven populations showed resistance to ready mix formulation of sulfosulfuron + metsulfuron, 8 populations were medium R/medium S and one population was susceptible. Similarly, 11 showed resistance to ready mix formulation of mesosulfuron + iodosulfuron, 7 populations were medium R/medium S and one biotype was susceptible. GR₅₀ values tested were in the range of 30110 g/ha in contrast to 5 g/ha at the time of recommendation.