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RI Turf: Species, Qualities, and Complexities
Five main species of turfgrass are used on RI golf courses: bentgrass, ryegrass, bluegrass, fescue, and poa annua. All five grass species are seeded with the exception of Poa annua, an invasive weed. Within the grass species there is a wide range of varieties, and mixes. The five different species and common varieties are described below, along with a summary of their benefits, drawbacks, and primary functions.
Bent
Creeping Bentgrass (Agrostis palustis)
For golfers, bentgrass is the preferred grass for the greens, tees, and
fairways. Bent grass grows without special care in moist soils of the
northern US, is a cool-season grass with a fine leaf texture, and is designed
for a low height of cut (1/4in-1/2in) which creates a fast playing surface.
The ability for bentgrass to handle this low height of cut is the primary
reason it is found on greens all over the country. Some of the drawbacks
of this fine grass include its high demand for water, poor drought, heat,
and wear tolerance, as well as high susceptibility to diseases.[3]
It also has a high rate of thatch buildup, and high nitrogen requirements,
which result in more fertilizer requirements.[4]
Despite the high maintenance needs of bentgrass, one superintendent said
that bentgrass symbolized "upscale" golf. Other superintendents
said it was resistant to diseases such as gray leaf spot, and mentioned
it grows well with poa annua. I was also told
that a good stand of bentgrass could handle a lot of traffic, and some
thought it had made the most improvements out of the genetically modified
grasses.
Velvet Bentgrass is the result of a long
term improvement program developed by Dr. Richard Skogley at the University
of Rhode Island, in cooperation with Seed Research, where it developed
the trade name SR 7200. Velvet bentgrass combines the low maintenance
aspects of older velvets with a dark green color, and good seed yields.
According to Seed Research, velvet bentgrass is the finest-textured, densest
bentgrass and it has long been recognized as forming the best putting
surfaces. [5]
Velvet bentgrass performs well under conditions of acid soils,
low fertility, and low maintenance. If velvet is grown properly, it is
very disease resistant, and can be cut as low as 3/32 inch. SR 7200 velvet
also has a high tolerance to drought, and overwatering only encourages
Poa annua, so it should be avoided.
Putter Bentgrass
Putter bentgrass showed a low percentage of Poa annua invasions,
according to a study conducted at UC Davis in 1994. [6].
Ryegrass
Perennial Ryegrass is the second most popular grass for tees and fairways.
Rye is a cool-season grass that germinates and establishes itself quickly,
thus it is excellent for overseeding. It also has good heat and cold tolerances,
and is best adapted to coastal regions such as RI. Ryegrass is the best
grass to mix with another species because it establishes itself quickly,
but is not a very strong, self supporting grass. Rye was never found alone
on any of the visited RI courses. The drawbacks of perennial ryegrass
are it has high water needs, and therefore has a low tolerance for drought.
[7]
The superintendents that were interviewed said they liked rye because
it "fills in quickly," and is a thick grass.
Bluegrass
Kentucky Bluegrass is found on the greens tees, fairways, and rough. It
is second to bent for popularity on the greens, and second to fescue on
the rough, and is the least popular on the tees and fairways. Kentucky
bluegrass is best adapted to mountainous regions, as well as the northeastern
US, thus it fits RI well. It has medium to high water needs, and a moderate
heat and drought tolerance. If it is mowed too short, it becomes much
more susceptible to heat. However, it is easy to grow, and has good resistance
to diseases such as
leaf spot and summer patch, both common in RI. It also has a good tolerance
for wear. Superintendents like it because of its disease resistance and
the fact that it creeps well. The interviewed superintendents reported
that the ideal golf course has bentgrass on the greens and blue grass
on the rough. The majority of athletic fields are seeded with bluegrass.
There was not a great deal of bentgrass that was found on the rough, most
likely because fescue is an even more drought tolerant and disease resistant
grass than blue; however this is only speculation.
Fescue
Fine-leafed Fescue is the most common grass on the rough, however it is
also found on the greens, tees, and fairways. The most common species
of fine-leafed fescues are Chewings fescue and Creeping Red fescue. Research
conducted at URI
shows fine fescues to have a higher drought tolerance than all of the
other grass species used by golf course superintendents in RI.[7]
Fescues are also very tolerant of low pH, fertility, and shade, and they
recover quickly from heat and drought. Fescue mixes well with Kentucky
blue grass, as well as other grasses. Superintendents commented that fescues
are great for the rough because of their hardiness and drought tolerance.
They also mentioned that insects hardly affect them, and they handle heat
and cold well. The major drawback of fescues it that they are difficult
to cut low, which is why they are rarely found outside the rough.
Poa annua
Poa is a weed, "a plant out of place," and can out compete any
planted grass due to its competitive nature, its adaptability, compatibility,
and capability to grow in wet soils and germinate quickly. Poa is found
on almost all golf courses in RI, as well as cemeteries, parks, and lawns.
This weed can germinate at a very low height of cut, is a prolific seeder,
and can withstand both shade and traffic. However, superintendents dislike
poa due to its invasive characteristics, and it becomes dormant during
the summers because it is an annual, and requires a great deal of maintenance
to keep the grass alive and green during the summer months. In addition,
poa has a number of other drawbacks other than turning brown during the
most popular golf season. It is susceptible to anthracnose (a common turfgrass
disease) it lacks heat and drought tolerance, and has a high demand for
water and chemicals. Poa also has a very low root system, which overall,
makes it a weak grass.
The chart below is a summary of the five turfgrass species that are found
in RI. I developed the chart based on information I gathered from RI superintendents
as well as data from URI's
Landscape and Horticultural Program, as well as several other sources.
[8]
The two categories were chosen based on what RI superintendents considered
to be the most important factors when
selecting a species or variety of turfgrass.
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