The advantages of diversity in turfgrass stands

As a turfgrass breeder, I collect plants from old stands of grass, including older golf courses, pastures, meadows, and sportsfields, primarily to find those plants that have survived and prospered under various stresses. Rarely, at these sites, do you find a monoculture of one species of grass, unless considerable effort has been made with herbicides to maintain a pure stand. Nature selects from a broad range of species and plants to find ones adapted to each microclimate.

Although most sports demand a consistent playing surface for a uniform ball bounce, roll and uniform footing, it is sometimes desirable to mix multiple cultivars of the same species or multiple species together to obtain a more sustainable surface.

Turfgrass trials and breeding trials are usually done on single cultivars of individual species. It would be difficult to place all the combinations that could be done in a trial but, many times, it is shown that combinations cannot only complement each other, they can be better than one cultivar by itself.

It may be that the highest density cultivar is not the best one for a blend or mixture, since it may come to dominate the stand. Studies have documented that, at seeding, you need significantly more smooth stalk meadowgrass on a weight basis than perennial ryegrass for it to dominate the stand, due to seedling vigour of the ryegrass.

Many UK golf courses are very old and already a mix of species

Recent drastic swings in weather from hotter, drier summers to colder winters may make even the species and plants present on these courses non-adapted.
In the United States, the emphasis is shifting to a more environmental management for many courses for many reasons. Cultivars of many cool season species in the United States need to survive hot, humid summer and cold winters, whilst European cultivars have often had less stress on them. The additional stress of golf buggies or cars on the turf can be hard on some species. Turf managers will need to stay connected to innovations in all areas.

A mixture of velvet bentgrass and creeping bentgrass has been in trials for a number of years and has been used for some golf greens. The newer creeping bentgrass match, more closely, velvet bentgrass density and texture, but the two species tend to be susceptible to different diseases. The velvet also tends to grow better with cool soil temperatures.

Often, in these mixes, the velvet predominates during the cool time of year or in the shade, and the creeping bentgrass when it is warmer. Both velvet and creeping bentgrass at fairway height required about 60% of the reference ET whilst annual meadowgrass required close to 100%.

Browntop bentgrass is being increasingly looked at for both golf course fairways and home lawns in the United States. In both fairway trials and low maintenance turf trials it has shown considerable promise.

Newer cultivars have higher resistance to diseases and more heat tolerance

They are often blended with fine fescues for both uses. They have been utilised for many years and occur naturally in these areas in the UK, but were often overlooked for home usage, partially since dryland bentgrass and browntop were considered the same species. In a low maintenance turf trial, with little fertiliser and no irrigation, in the Upper Midwest states, the bronwtop (colonial) bentgrass had high performance.

Turf breeders have developed tall fescues that are significantly finer and denser than even the cultivars available a few years ago. These have extensive drought tolerance, and new cultivars have demonstrated lower water usage. Usage as a sports turf has increased due to the improved characteristics. Usually, these are blended with smooth stalk meadowgrass, but may also have been blended with improved turf-type intermediate or annual ryegrass.

Species and cultivar diversity provides a buffer against environmental changes

Care must still be taken to select improved cultivars in the desired species. Evaluate the cultivar or species for the characteristics that are valuable to you.

Make sure you have cultivars and species that are actively growing during the heaviest use time, so repair can occur.

In Southern England, you may want to see what is performing the best in more continental climates. Currently, the UK is in a drought situation. I remember walking Hyde Park under a similar scenario a few years ago, and thinking a good turf-type tall fescue might be a better choice than the brown perennial ryegrass that was present.

Photo captions:
Top - Dr Leah A. Brillman
Middle - Ballyneal Golf Course in Colorado on sand dunes. Fine fescue and browntop bentgrass with a little smooth meadowgrass to start. Now, mostly fine fescue on greens and many fairways
Bottom - BayonneGolf Course on the Northeastern tip of New Jersey. The greens are creeping bentgrass/velvet bentgrass, fairways are browntop and fine fescue.