Herbicide Resistant Weeds

Inheritance of an ALS-cross-resistant common cocklebur (Xanthium strumarium) biotype.

Ohmes, G. A., Jr. and J. Kendig A. 1999. Inheritance of an ALS-cross-resistant common cocklebur (Xanthium strumarium) biotype. Weed Technology. 13: 100-103.

A greenhouse experiment was conducted from 1995 to 1996 to determine the inheritance of acetolactate synthase (ALS)-cross-resistant X. strumarium. ALS-susceptible biotypes were crossed with pollen from ALS-resistant biotypes. F1 plants were self-pollinated. F2 plants were sprayed post-emergence with a tank mixture of imazaquin at 280 g a.i./ha and chlorimuron at 18 g a.i./ha. Three distinct responses were observed: (1) no apparent effect (resistant), (2) yellowing of leaves with live terminals (intermediate) and (3) yellow leaves with dead terminals (typical symptoms of ALS-susceptible X. strumarium). Chi-square tests indicated that an incomplete dominance model did not fit the data. Responses one and two were combined and chi-square tests indicated that a complete dominance model fit the data. The cross-resistant trait appears to be a dominant to semi-dominant trait.