In early spring and late fall, bentgrass greens can appear especially patchy and multicolored. I have had golfers and maintenance staff members ask if the patchy appearance was the result of some disease or mutation – usually it’s not. To understand why this phenomenon occurs, it is important to know how bentgrasses are bred.
Bentgrass selections are synthetic cultivars. In this process, breeders will use six to 10 superior clones and vegetatively propagate them to maintain the purity of the lines. The clones are then randomly pollinated amongst themselves to produce seed. This method produces seeds that are high performing and similar, but genetically unique. Several other cool-season grasses, like tall fescue and perennial ryegrass, are bred similarly.
This isn’t the case with all grass selections. Grasses that are vegetatively propagated, like hybrid bermudagrass, zoysiagrass, St. Augustine grass, centipedegrass and seashore paspalum, along with grasses that produce seed from apomixis (Kentucky bluegrass) will produce genetically identical plants upon establishment.
As bentgrass greens mature, the genetic differences among individual plants become increasingly apparent. These unique populations segregate and establish clusters of different-colored turf. This phenomenon is different than the off-types of bermudagrass seen on ultradwarf greens, which can be caused by genetic mutation or contamination. In the case of bentgrass segregation, putting green performance is not impacted.
Textures of the populations remain similar due to the selection of superior clones, and the greens develop a classic appearance.
If segregation is not desired on a putting surface for aesthetic reasons, you can consider renovating to a modern creeping bentgrass, but understand that the varied appearance will return in the years after establishment. In most cases, embracing the classic look is desired, and remember that segregation will not impact playability. If you have any questions or concerns about managing bentgrass putting greens, reach out to your regional USGA agronomist.
Central Region Agronomists:
Zach Nicoludis, regional director – znicoludis@usga.org
Tom Gould, agronomist – tgould@usga.org
Information on the USGA’s Course Consulting Service
Contact the Green Section Staff