SENSITIVITY OF SELECTED FIELD CORN INBREDS (ZEA-MAYS) TO NICOSULFURON

A small percentage (< 5%) of dent corn inbreds was sensitive to the he rbicide nicosulfuron. Segregation within a backcross to inbred Ab18 de monstrated simple inheritance as a nuclear gene for corn sensitivity t o this herbicide. Greenhouse tests indicated that cytoplasmic or mater nal effects were not important in conditioning sensitivity. Tolerance in some crosses began to break down at application rates approaching t wice that registered. Sensitivity was controlled by a single autosomal recessive gene in the inbred Ab18. Further testing will be required t o determine whether this gene is common to other sensitive inbreds. Th orough screening continues to be necessary to identify sensitive elite inbreds in public and private breeding programs.