Presence of the Gene and ALS Mutation in Weedy Sensitive to Benzobicyclon.

Benzobicyclon has shown varying results in controlling weedy rice, including those with imidazolinone (IMI) resistance. Tolerance to benzobicyclon in cultivated rice, but not or -like cultivars, is conferred by a fully functional () gene. Herein, a diagnostic Kompetitive Allele Specific PCR (KASP) assay was developed to predict the genotype of weedy rice plants from 37 accessions and correlated to their response to benzobicyclon in the field. Two-thirds of the 693 weedy rice plants screened were tolerant to benzobicyclon (371 g ai ha, SC formulation) at 30 days after treatment (DAT). Thirty-four percent of plants were homozygous for the allele and 98% of these plants exhibited field tolerance. However, the genotype did not always correlate with field data. Only 52% of plants were considered sensitive, indicating that the single nucleotide polymorphisms (SNPs) chosen in the KASP assay are not a reliable tool in predicting homozygous plants. In an additional experiment, 86% of the 344 plants with at least one copy of the ALS trait harbored a allele, suggesting fields infested with IMI herbicide-resistant weedy rice are unlikely to be controlled with benzobicyclon.