mixtures will have greater genetic diversity and be more
disease resistant and more tolerant of pests and environmental
stresses than a single species.
mixtures must be balanced, or dominance of one species will
negate the benefits of the mixture.
ryegrass is best left out of mixtures for golf course fairways
research is needed, but tall fescue seeded 50:50 with Kentucky
bluegrass remained competitive after three years.
turfgrass species may be advantageous because a mixture will have
greater genetic diversity and exhibit greater tolerance of pests
and environmental stresses than a single species.
Many turfgrass managers use
mixtures of tall fescue (Festuca arundinacea) and Kentucky
bluegrass (Poa pratensis L.) to provide the best of both species
for athletic fields. Tall fescue, which has been used extensively
for athletic fields in the transition zone for many years, has
excellent traffic tolerance, but once damaged it is slow to
recover. Kentucky bluegrass has rhizomes, which may enhance the
healing process of a tall fescue + Kentucky bluegrass mixture once
Mixtures may also be more
resistant to disease. When Kentucky bluegrass in our plots was
infested by dollar spot (Sclerotinia homoeocarpa), which is not a
serious disease in tall fescue, mixtures retained better quality
than Kentucky bluegrass alone. Because tall fescue is more
susceptible to brown patch (Rhizoctonia solani) than Kentucky
bluegrass, mixtures retain better quality than tall fescue alone
in response to this disease.
Many golf course superintendents
in the transition zone have attempted to grow Kentucky bluegrass
in rough areas, but summer patch (Magnaporthe poae), perhaps the
most serious disease of Kentucky bluegrass in the transition zone,
makes this choice problematic.
The problem becomes exacerbated in
the secondary rough where soil moisture may become less consistent
than it is in the fairways or in the rough adjacent to fairways,
and alternating wetting and drying worsens summer patch. In this
situation, compatible Kentucky bluegrass + tall fescue mixtures
may provide a viable alternative. In shaded or partly shaded
rough, mixtures can be formulated that might include the
inherently shade-tolerant tall fescue species and Kentucky
bluegrass cultivars selected for shade tolerance.
We have had good success with
Kentucky bluegrass + tall fescue mixtures cut at 5/8 to 7/8 inches
during a 10-year interval and subjected to brief, but intensive,
simulated traffic. Nevertheless, our studies lack the day-to-day
stress found on the golf course, and superintendents should
experiment, perhaps by renovating part of a fairway to Kentucky
bluegrass + tall fescue mixtures, before making a long-term
To be successful, species
mixtures must be balanced, or dominance of one species will negate
the benefits of the mixture. Previously, it was not possible to
mix tall fescue and Kentucky bluegrass because the fescue tended
to segregate into patches in the established mixture. The newer,
more aggressive turf-type tall fescues increased the probability
that balanced mixtures could be attained.
The long-term objective of our
three research projects, which began in 1985, is to determine the
practicality of maintaining turf-type tall fescue in mixture with
Kentucky bluegrass and perennial ryegrass (Lolium perenne L.)
under varied management conditions.
Ten years of research at the
University of Missouri have shown that after three to five years,
perennial ryegrass will dominate in mixtures with tall fescue or
Kentucky bluegrass at high (2-inch) and low (5/8- to 7/8-inch)
mowing heights, with or without irrigation, and regardless of
nitrogen rates of 1 to 4 pounds per 1,000 square feet per year.
Because the dominant perennial ryegrass is highly susceptible to
gray leaf spot, it is best left out of mixtures for golf course
fairways and roughs. In the transition zone, perennial ryegrass is
best used for overseeding athletic fields because it germinates
and establishes more quickly than other species.
The objective of our first
study (1985-1989) was to determine whether compatible mixtures of
tall fescue, Kentucky bluegrass and perennial ryegrass could be
maintained at close mowing heights and under three nitrogen
regimes. This research was the basis for K.L. Hunt's Ph.D.
Results showed that selected,
blended tall fescue cultivars under nonirrigated conditions can
adapt to close mowing and remain competitive in mixture with
selected, blended Kentucky bluegrass cultivars for several years.
Under these same conditions, perennial ryegrass dominated both
species in mixtures. Nitrogen and cutting height had little effect
on botanical composition and had only occasional, minor effects on
The objective of the second study
(1990-1995) was to determine the influence of several management
factors on tall fescue, Kentucky bluegrass and perennial ryegrass
growing in mixtures. Results showed that selected, blended tall
fescue cultivars may be competitive in mixture with selected,
blended Kentucky bluegrass cultivars under varied management
conditions, including irrigation or no irrigation, close mowing
and brief but intense traffic. The study also confirmed our
earlier observations that perennial ryegrass will dominate in
mixtures with tall fescue and Kentucky bluegrass. Disease
incidence was a principal influence on turfgrass quality, and the
advantage of mixing species for disease resistance was apparent.
fescue is more susceptible than Kentucky bluegrass to brown patch
Our most recent study
(1995-present) attempted to determine the influence of seeding
rate and Kentucky bluegrass blend composition on the
competitiveness of tall fescue in mixture with Kentucky bluegrass.
Three Kentucky bluegrass blends -
A (SR 2000 + SR 2010), B (Blacksburg + Midnight + Glade + Baron)
and C (Limousine + Princeton 105 + America) - and a tall fescue
blend (Houndog V + Jaguar III + Falcon II + SR 8210 + Rebel III +
Mustang II) were seeded in September 1996. Mixtures of each of the
three Kentucky bluegrass blends with the tall fescue blend were
also seeded, with tall fescue comprising 90 percent (H), 50
percent (M), and 20 percent (L) of each mixture by seed weight for
a total of nine mixture combinations.
The test was planted in two
adjacent locations, one irrigated and the other not. Turf was
mowed at 2 inches as needed and received 3 to 4 pounds N per 1,000
square feet per year, with most of the fertilizer applied in the
October 1999, blends and mixtures were recovering from summer
drought. The Kentucky bluegrass blends shown here are dormant; the
green plots are tall fescue blends and tall fescue + Kentucky
Tall fescue was the dominant
species of mixture H at 71 percent after one year and 63 percent
after three years. Mixture M consisted of 42 percent tall fescue
at one year and 57 percent after three years. Kentucky bluegrass
was the dominant species of the L mixture after one year, but
declined by 30 percent from the first to the third year so that
Kentucky bluegrass and tall fescue were evenly mixed at three
years after seeding. Mixture A consisted of an average 58 percent
tall fescue and 41 percent Kentucky bluegrass. Mixtures B and C
were evenly balanced between the two species.
Trends for mixture composition
according to seeding rate were similar to that of the nonirrigated
location except that Kentucky bluegrass appeared tobe more
competitive in the irrigated location at three years after
seeding, especially at the L (90 percent Kentucky bluegrass)
seeding rate. Although tall fescue was the dominant component of
mixture A in the nonirrigated location, the species were more
evenly balanced in the irrigated location at one and three years
after seeding. Mixtures B and C also showed good balance after
three years with a difference between species of 10 percent or
The advantage of mixing species
was evident on several occasions. For example, average summer 1999
quality rating for irrigated tall fescue was 5.5 (9 = best) and
5.0 for Kentucky bluegrass blend B; however, quality for the
mixture of tall fescue + blend B was 6.3.
Both seeding rate and Kentucky
bluegrass blend composition affected mixture composition three
years after seeding, depending on irrigation management. Tall
fescue was competitive in mixture with Kentucky bluegrass at all
seeding rates and in combination with all three Kentucky bluegrass
Three to five years of additional
research will be needed. For example, seeding date may be critical
to success with mixtures. Late August, and September are often
cited as the best times for establishing tall fescue and Kentucky
bluegrass. Seeding in October and November may result in loss of
seedling turf over the winter; therefore, it is difficult to
predict what the balance of tall fescue to Kentucky bluegrass, in
a late-seeded mixture, would be after five years.
How much seed should be used? In
our earlier studies, we suggested 90 percent tall fescue by seed
weight because we thought that tall fescue would need an early
edge with the more aggressive Kentucky bluegrass. However, our
most recent studies showed that a blend of tall fescue seeded
50:50 with Kentucky bluegrass by seed weight would remain
competitive after three years. Still, we want to reserve judgment
until we complete our five-year population counts in 2001.
In summary, the proven
compatibility of newer turf-type tall fescues with Kentucky
bluegrass in mixture gives golf course superintendents an option
for turf in rough areas that was not practical 15 years ago.
Furthermore, tolerance of many cultivars of both species to close
mowing suggests that tall fescue-Kentucky bluegrass mixtures may
have potential for transition zone fairways where alternatives to
warm-season grasses are needed. On-site testing for a period of
three to five years under fairway management conditions is needed
to determine whether this is feasible.
The author thanks
Ken Hunt, Ph.D., and Brad Fresenburg, University of
Missouri-Columbia; Suleiman Bughrara, Ph.D., Michigan State
University; and Erik Ervin, Ph.D., Virginia Tech University, for
their participation in this research. The author also thanks the
Mississippi Valley GCSA and the Heart of America GCSA for
grants-in-aid to support parts of this research.
- Brede, A.D. 1993. Tall
fescue/Kentucky bluegrass mixtures: effect of seeding rate,
ratio, and cultivar on establishment characteristics.
International Turfgrass Society Research Journal 7:1005A-1005G.
- Davis, R.R. 1958. The effect of
other species and mowing height on the persistence of lawn
grasses. Agronomy Journal 50:671-673.
- Hall, J.R. 1977. Effect of
cultural factors on tall fescue-Kentucky bluegrass sod quality
and botanical composition. p. 367-377. In: J.B. Beard (ed.),
Proceedings of the 3rd International Turfgrass Research
Conference, Munich, Germany. ASA, Madison, Wis.
- Harkess, R.D. 1970. Competition
between tall fescue and perennial ryegrass in pure and mixed
swards under simulated field condition. Journal of Applied
- Hsiang, T., K. Carey, B. He and
J.E. Eggens. 1997. Composition of mixtures of four turfgrass
species four years after seeding under non-wear conditions.
International Turfgrass Society Research Journal 8:671-679.
- Hunt, K.L., and J.H. Dunn.
1993. Compatibility of Kentucky bluegrass and perennial ryegrass
with tall fescue in transition zone turfgrass mixtures. Agronomy
- Laycock, R.W., and P.M.
Canaway. 1980. A new optical point quadrat frame for the
estimation of cover in close mowed turf. Journal of the Sports
Turf Institute 56:91-92.
- Sellmann, Mark. 1998. Kentucky
bluegrass comes back to fairways. Golf Course Management
Dunn, Ph.D., is a professor of horticulture in the college
of agriculture, food and natural resources at the University of