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PR-479

2002 Cool-Season Grass Grazing Variety Report: Tolerance to Horses

R.F. Spitaleri, J.C. Henning, L.M. Lawrence, G.D. Lacefield, T.D. Phillips, B. Coleman, and D. Powell

Introduction

Cool-season grasses such as bluegrass, tall fescue, and orchardgrass are dominant pasture grasses for horses in Kentucky. While variety evaluations for yield have been carried out for many years, little work has been done to establish the effect of variety on persistence when subjected to close, continuous grazing by horses.

The purpose of this report is to summarize current research on the grazing tolerance of varieties of tall fescue and orchardgrass and other species when subjected to continuous and heavy grazing pressure by horses within the grazing season. The main focus will be on plant stand survival.

Description of the Tests

Tests were established in Lexington in the fall of 1999, 2000, and 2001. The soils at this location are well-drained silt loams and are well suited to tall fescue, orchardgrass, and other cool-season grasses. Plots were 5 ft x 15 ft in a randomized complete block design with each variety replicated six times. Plots were seeded at the recommended seeding rate per acre and were planted into a prepared seedbed using a disk drill. Grazing was continuous from April to October.

Plots were grazed down to below 4 inches quickly and kept at that height or below for the remainder of the grazing season. Supplemental hay was fed during periods of slowest growth. Visual ratings of percent stand were made in the fall and spring after each grazing season. Grass plots were fertilized with 60 pounds of actual N per acre in the spring, and other fertilizer (lime, P, and K) was applied as needed.

Results and Discussion

Weather data for Lexington for 2001 and 2002 are presented in Table 1. After a wet spring, Kentucky experienced the fourth hottest and driest summer on record. Data on percent stand are presented in Tables 2, 3, and 4.

Statistical analyses were performed on all entries (including experimentals) to determine if the apparent differences are truly due to variety. Varieties not significantly different from the highest numerical value in a column are marked with one asterisk (*). To determine if two varieties are truly different, compare the difference between the two varieties to the Least Significant Difference (LSD) at the bottom of the column. If the difference is equal to or greater than the LSD, the varieties are truly different when grown under the conditions at a given location. The Coefficient of Variation (CV), which is a measure of the variability of the data, is included for each column of means. Low variability is desirable, and increased variability within a study results in higher CVs and larger LSDs.

In general, commercial varieties of tall fescue and orchardgrass tolerated overgrazing well (Tables 2, 3, and 4), but the varieties of timothy, bluegrass, and prairiegrass (Bromus wildenoii) in these trials did not. The sensitivity of timothy and prairiegrass to heavy grazing is not surprising, as these are both erect species and sensitive to heavy defoliation. Bluegrass as a species is expected to be more tolerant of heavy grazing. However, Ginger is intolerant of overgrazing (Tables 2, 3), while Kenblue and other bluegrasses show good tolerance (Table 4.)

Perennial ryegrasses vary in tolerance to grazing. Several ryegrasses and a ryegrass hybrid (Duo) show good survival (Tables 3, 4). Mara and Duo were among the most persistent after two seasons of grazing (Table 3).

Differences in tolerance among varieties could be due to true grazing tolerance but also to preference, especially where highly palatable species like bluegrass and ryegrass are alongside tall fescue. These data should be taken as an indication of tolerance to short durations of overgrazing. For best pasture stands, forage grasses should not be abused as in this study.

The lack of a defined "grazing-tolerant variety" for these species makes absolute interpretation difficult. For example, endophyte-infected Kentucky 31 (KY31+) is known to be grazing tolerant. However, there are no proven grazing-tolerant varieties for the other species. Still, certain varieties are clearly more tolerant than others (Mara versus Polly II).

Table 5 summarizes information about distributors and persistence across locations and years for all varieties in these tests. Varieties are listed in alphabetical order with experimental varieties listed at the bottom. Shaded areas indicate that the variety was not in that particular test (labeled at the top of the column), while clear blocks mean the variety was in the test. A single asterisk (*) means that the variety was not significantly different from the top-yielding variety in that study. It is best to choose a variety that has performed well over several years.

Summary

These studies indicate that there are varieties of cool-season grasses that can tolerate overgrazing for one to three seasons and still maintain reasonable stands. This information should be used along with yield and other information (for example, relative maturity in spring) in selecting the best grass variety for each individual use. It is not generally recommended that tall fescue or orchardgrass or other cool-season grasses be continuously overgrazed as was done in this trial. Although several varieties expressed tolerance to the level of grazing pressure used in these trials, overgrazing greatly reduces yield and therefore profitability of these varieties. This information should be an indication of those varieties that will better withstand the occasional overgrazing that sometimes occurs.

Good management for maximum life from any grass would be to allow it to get completely established before grazing and to avoid overgrazing it during times of extreme stress, such as drought.

Mention or display of a trademark, proprietary product, or firm in text or figures does not constitute an endorsement and does not imply approval to the exclusion of other suitable products or firms.

Table 1. Temperature and rainfall at Lexington during the 2001 and 2002 growing seasons.

 

2001

2002

Temp

Rainfall

Temp

Rainfall

ºF

DEP

IN

DEP

ºF

DEP

IN

DEP

JAN

31

0

0.9

-1.9

38

+7

2.12

-0.7

FEB

40

+5

3.2

0

38

+3

1.28

-1.9

MAR

40

-4

2.7

-1.7

45

+1

7.93

3.5

APR

59

+4

1.7

-2.2

58

+3

4.19

0.3

MAY

66

+2

4.9

+0.4

61

-3

4.36

-0.1

JUN

71

-1

2.0

-1.6

74

+2

2.45

-1.2

JUL

75

-1

5.6

+0.6

78

+2

1.10

-3.9

AUG

76

+1

4.8

+0.8

77

+2

0.95

-3.0

SEP

65

-3

3.0

-0.2

72

+4

4.90

1.7

OCT

56

-1

3.6

+1.1

55

-2

5.61

3.0

NOV

51

+6

2.8

-0.6

43

-2

3.76

0.4

AVG

57.3

+0.7

3.2

-0.5

58.1

+1.6

3.5

-0.2

DEP is departure from the long-term average for that location.

 

Table 2. Percent stand of forage grasses planted October 4, 1999, at Lexington, Kentucky, in a horse grazing tolerance study.

Variety

Type

Percent Stand

Sep 21, 2000

Apr 4, 2001

Oct 15, 2001

Apr 2, 2002

Oct 11, 2002

Commercial Varieties — Available for Farm Use

Festorina

tall fescue1

95

86

67

78

67*

Benchmark

orchardgrass

98

86

66

79

63*

Cattle Club

tall fescue

97

85

70

78

63*

Tekapo

orchardgrass

99

81

70

71

61*

Haymate

orchardgrass

99

88

73

76

58*

Select

tall fescue

95

87

65

76

54*

Bronson

tall fescue

87

76

50

58

53*

Stargrazer

tall fescue

95

78

54

68

46

Ginger KB 6

Kentucky bluegrass

50

63

5

33

5

Horseblend

timothy

40

42

5

23

4

Polly II

tetraploid perennial ryegrass

61

63

5

32

3

Experimental Varieties — Not Available for Farm Use

KYOG 2

orchardgrass

100

88

71

80

68*

OG 9705g

orchardgrass

98

88

73

82

68*

KYFA 9304

tall fescue

99

89

67

78

68*

Ky31-

tall fescue

98

87

69

81

66*

KYFA 9301

tall fescue

98

87

63

77

63*

KYTF 2

tall fescue

100

89

66

75

53*

Ampac pp6

mixture

89

79

41

58

38

Ampac pp7

mixture

72

66

32

54

30

KY-Early

timothy

45

55

3

29

8

KYPP 9301

timothy

43

53

6

31

4

 

Mean

-

84

77

49

63

45

CV, %

-

13.04

10.08

21.34

17.41

31.54

LSD, 0.05

-

12.50

8.87

11.87

12.48

16.21

*

Not significantly different from the highest value in the column based on the 0.05 LSD.

1

All tall fescues are endophyte free.

 

Table 3. Seedling vigor rating and percent stand of forage grasses planted September 19, 2000, at Lexington, Kentucky, in a horse grazing tolerance trial.

Variety

Type

Seedling Vigor1
Oct 31, 2000

Percent Stand

Apr 9, 2001

Oct 15, 2001

Apr 2, 2002

Oct 11, 2002

Commercial Varieties — Available for Farm Use

Duo

festulolium

5

90

66

82

76*

Mara

diploid perennial ryegrass

5

90

77

89

73*

Cattle Club

tall fescue2

4

90

69

78

68*

Barcarella

tall fescue

3

88

56

70

65*

Tekapo

orchardgrass

2

89

77

83

64*

Stargrazer

tall fescue

3

89

62

75

63*

Haymate

orchardgrass

3

90

68

75

53

Kokanee

tall fescue

4

90

58

73

36

Ginger

Kentucky bluegrass

1

90

9

43

8

Tuukka

timothy

2

90

18

50

6

Experimental Varieties — Not Available for Farm Use

OG 9705g

orchardgrass

2

90

61

68

55

K5568k

orchardgrass

3

90

73

79

53

K5633d

prairie brome

5

81

8

33

4

K5632m

prairie brome

4

84

7

28

3

 

Mean

-

3.2

89

50

66

45

CV, %

-

18.18

2.47

22.05

19.01

27.24

LSD, 0.05

-

0.67

2.53

12.83

14.48

14.08

*

Not significantly different from the highest value in the column based on the 0.05 LSD.

1

Based on 0 to 5 scale with 5 being the most vigorous.

2

All tall fescues are endophyte free.

 

Table 4. Seedling vigor rating and percent stand of forage grasses sown September 12, 2001, at Lexington, Kentucky, in a horse grazing tolerance study.

Variety

Type

Seedling Vigor1
Nov 2, 2001

Percent Stand

Apr 4, 2002

Oct 15, 2002

Commercial Varieties — Available for Farm Use

Aries

diploid perennial ryegrass

5

90

79*

Grand Daddy

tetraploid perennial ryegrass

5

90

78*

Kenblue

forage bluegrass

2

89

77*

Slezanka

forage bluegrass

3

88

74*

Platini

forage bluegrass

2

90

70*

Crown Royale

orchardgrass

4

90

66*

Albert

orchardgrass

3

90

62

Quartet

tetraploid perennial ryegrass

5

78

62

Ky31+ 2

tall fescue

4

90

60

Prairie

orchardgrass

4

90

58

Johnstone

tall fescue

4

89

48

Fure

meadow fescue

3

90

21

Clair

timothy

2

89

21

Maverick Gold

diploid perennial ryegrass

5

28

21

Colt

timothy

3

90

15

Experimental Varieties — Not Available for Farm Use

KYFA9301

tall fescue

4

90

71*

KYFA9304

tall fescue

4

90

61

Ky31- 2

tall fescue

4

90

58

OG 9705g

orchardgrass

2

90

57

PP 10

mixture

3

88

48

PP 11

mixture

5

48

23

 

Mean

 

3.5

84

54

CV, %

 

12.46

5.10

26.00

LSD, 0.05

 

0.50

4.92

16.01

*

Not significantly different from the highest numerical value in the column based on the 0.05 LSD.

1

Based on 0 to 5 scale with 5 being most vigorous.

2

“+” indicates variety is endophyte infected, “-“ indicates variety is endophyte free.

 

Table 5. Persistence of forage grasses under heavy grazing pressure by horses across years.

 

Lexington

19991

2000

2001

Variety

Species

Proprietor/KY Distributor

April 20022

Oct 2002

April 2002

Oct 2002

April 2002

Oct 2002

Commercial Varieties — Available for Farm Use

Albert

orchardgrass

University of Wisconsin

 

 

 

 

*

 

Aries

diploid perennial ryegrass

Ampac Seed Company

 

 

 

 

*

*

Barcarella

tall fescue

Barenbrug

 

 

*

*

 

 

Benchmark

orchardgrass

FFR Cooperative

*

*

 

 

 

 

Bronson

tall fescue

Ampac Seed Company

 

*

 

 

 

 

Cattle Club

tall fescue

-

*

*

*

*

 

 

Clair

timothy

public

 

 

 

 

*

 

Crown Royale

orchardgrass

Grassland Oregon

 

 

 

 

*

*

Colt

timothy

FFR Cooperative

 

 

 

 

*

 

Duo

festulolium

Ampac Seed Company

 

 

*

*

 

 

Festorina

tall fescue

Advanta Seeds West

*

*

 

 

 

 

Fure

meadow fescue

DLF-Jenks

 

 

 

 

*

 

Ginger

Kentucky bluegrass

Dye Seed Ranch, Inc.

ProSeeds Marketing

 

 

 

 

 

 

Grand Daddy

tetraploid perennial ryegrass

Smith Seed Services

 

 

 

 

*

*

Haymate

orchardgrass

FFR Cooperative

*

*

*

 

 

 

Horseblend Dolina plus Tundra

timothy

DLF-Jenks

 

 

 

 

 

 

Johnstone

tall fescue

Proseeds Marketing

 

 

 

 

*

 

Kenblue

forage bluegrass

public

 

 

 

 

*

*

Kokanee

tall fescue

Ampac Seed Company

 

 

*

 

 

 

KY 31+

tall fescue

public

 

 

 

 

*

 

Mara

diploid perennial ryegrass

Barenbrug

 

 

*

*

 

 

Maverick Gold

diploid perennial ryegrass

Ampac Seed Company

 

 

 

 

 

 

Platini

forage bluegrass

DLF-Jenks

 

 

 

 

*

*

Polly II

tetraploid perennial ryegrass

FFR Cooperative

 

 

 

 

 

 

Prairie

orchardgrass

Turner Seed, Inc. of Kentucky

 

 

 

 

*

 

Quartet

tetraploid perennial ryegrass

Ampac Seed Company

 

 

 

 

 

 

Select

endophyte free tall fescue

FFR Cooperative

*

*

 

 

 

 

Slezanka

forage bluegrass

DLF-Jenks

 

 

 

 

*

*

Stargrazer

tall fescue

FFR Cooperative

 

 

*

*

 

 

Tekapo

orchardgrass

Ampac Seed Company

*

*

*

*

 

 

Tuukka

timothy

Ampac Seed Company

 

 

 

 

 

 

Experimental Varieties — Not Available for Farm Use

Ampac PP7

mixture

Ampac Seed Company

 

 

 

 

 

 

Ampac PP6

mixture

Ampac Seed Company

 

 

 

 

 

 

K5568k

orchardgrass

Ampac Seed Company

 

 

*

 

 

 

K5632m

prairiegrass

Ampac Seed Company

 

 

 

 

 

 

K5633d

prairiegrass

Ampac Seed Company

 

 

 

 

 

 

KY-Early

timothy

University of Kentucky

 

 

 

 

 

 

Ky31-

tall fescue

University of Kentucky

*

*

 

 

*

 

KYFA9301

tall fescue

University of Kentucky

*

*

 

 

*

*

KYFA9304

tall fescue

University of Kentucky

*

*

 

 

*

 

KYOG2

orchardgrass

University of Kentucky

*

*

 

 

 

 

KYPP9301

timothy

University of Kentucky

 

 

 

 

 

 

KYTF2

tall fescue

University of Kentucky

*

*

 

 

 

 

OG9705g

orchardgrass

FFR Cooperative

*

*

*

 

*

 

PP 10

mixture

Ampac Seed Company

 

 

 

 

*

 

PP 11

mixture

Ampac Seed Company

 

 

 

 

 

 

1

Establishment year.

2

Date of visual estimation of percent stand.

*

Not significantly different from the most persistent variety in the test. Shaded boxes indicate that the variety was not in the test. Open boxes indicate the variety was in the test, but persistence was significantly less than the top-ranked variety in the test.

 


Equal opportunity statement