Herbicide Resistant Weeds

Resistance of some Phalaris minor Retz. biotypes to isoproturon but not to pendimethalin.

Samunder Singh, R. K. Malik, Y. P. Malik, V. K. Garg, and S. Singh. 1993. Resistance of some Phalaris minor Retz. biotypes to isoproturon but not to pendimethalin. Integrated weed management for sustainable agriculture. Proceedings of an Indian Society of Weed Science International Symposium, Hisar, India, 18-20 November 1993. 2: 125-130.

In pot experiments conducted in screenhouses, graded doses of isoproturon and pendimethalin (0-1000 g/ha) were applied to putatively resistant, partially resistant and susceptible biotypes of Phalaris minor (wild canary grass). Wild canary grass biotypes from Amin (Kurukshetra district) and Lalodha (Hisar district) were found to be highly resistant to isoproturon, whereas biotypes collected from Garhi Gujran (Karnal district) and Balana (Ambala district) were found to be partially resistant to isoproturon. The GR50 values (based on percentage mortality) were 390, 385, 236 and 228 g for Amin, Lalodha, Garhi Gujran and Balana biotypes, resp., compared to 103 g for the HAU (Hisar district) susceptible biotype. Biotypes from Amin, Kutail (Karnal district) and HAU treated with pendimethalin were found to be highly sensitive to this herbicide, their GR50 values being only 76, 57 and 57 g, resp. The GR50 of resistant biotypes, as calculated in pot experiments, were about 3- to 5-fold less than those found in field trials at Lalodha, Amin and Balana (all in Haryana).