Minimizing Thatch and Mat Development in a Newly Seeded Creeping Bentgrass Golf Green

Excessive (>1.3 cm) thatch and mat layering of turfgrass is considered undesirable because it reduces hydraulic conductivity, water infiltration, increases localized dry spots and pest problems, and reduces pesticide effectiveness and turf tolerance to temperature extremes. The objective of this 2-yr study was to determine the efficacy of topdressing alone and in combination with several mechanical and biological methods to control thatch–mat accumulation in a newly established ‘L-93’ creeping bentgrass [Agrostis stolonifera L. var palustris (Huds.) Farw.] sand-based golf green. Mechanical and biological methods included vertical mowing at various depths and timings, core cultivation, grooming, a biological thatch control agent (Thatch-X), and combinations of core cultivation with grooming, core cultivation with vertical mowing, and core cultivation combined with grooming and vertical mowing. No treatment prevented thatch–mat accumulation, and thatch–mat depth for all treatments were similar to, or greater than, the untreated at the end of the study. Increases in percent organic matter content during the study ranged from 53% for core cultivation combined with grooming and vertical mowing to 123% for the untreated. Combinations of core cultivation plus vertical mowing with or without grooming were the most effective at minimizing thatch–mat accumulation. These treatments decreased percent organic matter 38 and 45%, respectively, compared with the untreated. Surface hardness was reduced an average of 19% by treatments that included core cultivation, and the cultivation treatments increased water infiltration rates an average of 58% in 2001 and 188% in 2002 compared with the untreated. Turf quality was not adversely affected by any management practice and remained acceptable (≥7.0) throughout the study.