Possible concern arises when coring is done after the pre-emergent herbicide is applied. The belief is coring will break the herbicide barrier resulting in increased weed germination, establishment and invasion. Rresearch on both cool and warm season turfgrasses found that coring after a pre-emergent application, to a turf that has good density, no increase in weed pressure was found (1, 2).
1. Branham, B.E. and P.E. Rieke. 1986. Effects of turf cultivation practices on the efficacy of preemergence grass herbicides. Agronomy Journal 78:1089-1091.
2. Johnson, B.J. 1982. Oxadiazon treatments on overseeded putting green turf. Weed Science 3):335-338.