Molecular Mechanisms of Resistance against PSII-Inhibiting Herbicides in from the Czech Republic.

L. (redroot pigweed) is one of the most problematic weeds in maize, sugar beet, vegetables, and soybean crop fields in Europe. Two pigweed amaranth biotypes (R1 and R2) from the Czech Republic resistant to photosystem II (PSII)-inhibiting herbicides were analyzed in this study.

Enhanced metabolism and target gene overexpression confer resistance against acetolactate synthase-inhibiting herbicides in Bromus sterilis.

Background: Intensive application of acetolactate synthase (ALS)-inhibiting herbicides has resulted in herbicide-resistance in many weeds, including Bromus sterilis. The present study was conducted to identify the mechanisms conferring resistance to ALS-inhibiting herbicides in a Bromus sterilis biotype.

Results: Dose-response studies revealed the resistant biotype to be 288 times less sensitive to pyroxsulam than the susceptible biotype.