It is common for a newly seeded green to grow in well, with bentgrass collars showing thinning and turf damage.
Collars are commonly more susceptible to mechanical damage from mowers. The twisting and turning of mowers causes a rolling action to bentgrass stolons (horizontal stems with longer leaves) that develop at the higher cut turf in collars and greens approaches.
The higher height of cut of collars also means more leaf surface area for mowers to damage leaves and stolons of the young and tender bentgrass.
Bentgrass growing at greens height of cut -- compared to a higher collar height -- develop, when mature, into finer leaved, more dense turf.
A fully developed bentgrass putting green will have no obvious leafy stolons, when maintained under a close height of cut, and will be less susceptible to mower mechanical turf damage.
In collars, it is the young, leafy, long stolons that are more prone to mechanical damage.
Additionally, great care should be taken when mowing a young, newly seeded bentgrass green. Train operators to mow in straight lines across a green and turn the mower after it has moved completely off of the bentgrass turf.