Cultivation and Topdressing Requirements for Thatch Management in A and G Bentgrasses and Creeping Bluegrass

Empirical observations suggest certain new cultivars of creeping bentgrass (Agrostis stolonifera L.) with high shoot density require more intensive topdressing and core aeration to control thatch compared to less dense cultivars such as 'Penncross'. In addition, a variety of Poa annua var. reptans Hausskn., 'DW-184', has recently been released for putting green use but management requirements are undocumented. The objective of our project was to determine the core aeration and topdressing requirements for thatch management of creeping bentgrass cultivars 'A-4', 'G-2', and 'Penncross' as compared to 'DW-184'. Plots were established on a sand-based root zone and maintained as putting green turf for 3 years. A factorial treatment arrangement was used to assess the effects of core aeration and topdressing on thatch, topdressing removal, turf quality, and disease. Both 'A-4' and 'G-2' produced more organic matter as (thatch/mat) than 'Penncross' and 'DW-184'. Grass type, core aeration frequency, and topdressing regime affected the amount of topdressing removed by mowing. An interaction between grass type and topdressing regime showed biweekly topdressing with verticutting resulted in less topdressing removal from all grasses except 'G-2' compared to monthly topdressing without verticutting. Since no more than 3% of the topdressing applied was removed from any single treatment, however, the overall impact of grass type, core aeration frequency, or topdressing regime are unlikely to affect turf response. Both 'A-4' and 'G-2' provided consistently better quality turf than 'Penncross' or 'DW-184' at 3.2 mm mowing height, though 'A-4' was more susceptible to dollar spot disease (Sclerotinia homeocarpa F.T. Bennett) than 'Penncross'or 'G-2'. Cultivation and topdressing methods for management of 'A-4' and 'G-2' bentgrasses do not differ substantially from 'Penncross' or 'DW-184' creeping bluegrass.