St. Augustinegrass Preformance In North Florida

A.E. Dudeck
University of Florida, Gainesville
Institute of Food and Agricultural Sciences

St. Augustinegrass is a popular lawn grass in Florida. Today, relatively few cultivars are available commercially, although many experimental selections are in various stages of development throughout southern United States. Purpose of this ongoing study is to evaluate adaptation and performance of 12 St. Augustinegrass selections from various sources. These include six commercially available cultivars as well as six experimental clones, two of which were collected in the State of Hawaii.

Materials and Methods

Twelve St. Augustinegrasses were plug planted in field plots at the IFAS Turfgrass Field Laboratory, Gainesville, FL on 8 Aug. 1995. A total of six prerooted plugs of each entry, approximately six inches in diameter and 3.5 inches deep were planted on 2-foot centers in 8 by 12 foot plots. Grasses were replicated four times in a randomized block design. The Arredondo fine sand (loamy, siliceous, hyperthermic Grossarenic Paleudult) had a soil pH of 6.6 and was fumigated with methyl bromide prior to planting. Ten days after planting, grasses were fertilized weekly at a rate of 0.5 pound of nitrogen per 1000 square feet with a 16-4-8 fertilizer until 29 Sept. 1995 . Fifty percent of the nitrogen was derived from sulfur-coated urea. Irrigation was applied daily to meet evapotranspiration need. Commencing on 8 Sept. 1995, plots were mowed weekly with a mulching mower at a height of three inches to encourage lateral growth.

During the first full-growing season of 1996, fertilizer was applied at a rate of one pound of nitrogen per 1000 square feet on 31 May, 14 June, 17 July, and 16 Sept. Fertilizer carriers were 21-8-11, sewage sludge, sewage sludge, and 21-8-11, respectively. Plots were mowed two to three times per week with a mulching mower set at a mowing height of 2.5 inches until 13 June 1996 when mowing height was lowered to 2.0 inches.

During the second growing season of 1997, a fertilizer with a 29-3-5 ratio containing atrazine herbicide was applied in March. Sewage sludge was applied in May. An 18-6-12 fertilizer was applied in late August. All fertilizers were applied at a rate of one pound of nitrogen per 1000 square feet.

During the third growing season of 1998, a 29-3-5 fertilizer with atrazine herbicide was applied in April. Sewage sludge was applied in June. A 21-0-2- fertilizer was applied in September. All fertilizers were applied at a rate of one pound of nitrogen per 1000 square feet.

Mowing with a rotary mower during 1997 and 1998 was at a height of 3.0 inches with a frequency of one mowing per week. Clippings were not removed. Supplemental irrigation was applied daily at a rate to meet evapotranspiration loss.

Visual ground cover estimates were taken by up to three independent observers on a weekly basis from time of planting to 20 November 1995. Visual estimates of ground cover were taken biweekly during the 1996 growing season. These data were summarized and presented in tabular form on a monthly basis. Rate of ground cover was calculated as a summation of average monthly ground cover estimates.

Turf quality, density, color, texture, and seed heads were visually rated by up to four independent observers during the 1996 to 1998 growing seasons. A scale of 1 to 9 was used where a rating of 9=best turf quality, density, dark-green color, finest leaf texture, and fewest seed heads. Color of anther and stigma were visually rated on a 1 to 5 scale where 1=white or yellow and 5=purple color. Gray leaf spot disease was visually rated only once on 31 May 1996 on a scale of 1 to 5 where 1=most infection and 5=no infection. Data were summarized and presented in tabular form on a seasonal basis where spring included months of March through May; summer included months of June through August; fall included months of September through November; and winter included months of December through February. All data were subjected to analysis of variance and means were separated using Waller-Duncan k-ratio t-test at P=0.05 level.

Results and Discussion

Rate of ground cover establishment differed among grasses (Table 1). FL-1997-6 and Raleigh St. Augustinegrass had best establishment rates which averaged 46%. No grass, however, had more than 33% ground cover at close of the growing season in November of 1995.

Grasses differed in monthly as well as seasonal average ground cover in 1996 (Table 2). FL-1997-6, MSA-11, and Raleigh increased most rapidly and had highest seasonal ground cover average of 74%. All grasses were essentially fully established by September of 1996 with exception of Seville, which averaged only 66% cover at that time.

Turf quality, density, and color differed between grasses throughout the 1996 growing season (Tables 3 and 4, respectively). MSA-31 was superior to all other grasses in turf quality and density. It had a seasonal average score of 7.6 for turf quality and a seasonal average score of 8.6 for turf density.

Grasses having darkest green colored foliage, which averaged 6.7, included FHSA-115, FHSA-117, FL-1997-6, Floratam, Floratine, and MSA-31 (Table 4).

Although grasses differed in turf quality throughout the second growing season of 1997, nine grasses had equal seasonal averages for turf quality (Table 5). Grasses having best seasonal turf quality scores, which averaged 5.6, included FHSA-115, FHSA-117, FL-1997-6, Floralawn, Floratam, Floratine, MSA-11, MSA-31, and Palmetto.

Grasses having best seasonal average scores for density, which averaged 7.2 during the second growing season of 1997, included FL-1997-6, MSA-11, and MSA-31 (Table 6).

Grasses having best seasonal average scores for dark-green color, which averaged 5.9 during the 1997 growing season, included FHSA-115, FHSA-117, FL-1997-6, Floralawn, Floratam, and Floratine (Table 6).

During the third growing season of 1998, FL-1997-6 had highest seasonal turf quality score of 6.9 (Table 7). It also had highest seasonal average turf density score of 7.2 as well as darkest green foliage score of 6.5 (Table 8).

Grasses that had finest leaf texture scores, which averaged 6.1, included FL-1997-6, MSA-10, MSA-11, MSA-31, and Seville (Table 9). Grasses that produced fewest seed heads, which averaged 7.3, included FHSA-115, MSA-31, and Seville. Most grasses showed good resistance to Gray leaf spot disease with the exceptions of FHSA-115, FHSA-117, and Floratine which were highly susceptible. Caution is warrented in drawing conclusions on Gray leaf spot resistance from these limited data. No differences were found between grasses when rated for anther color, but stigma colors differed widely. Grasses that had a white- colored stigma included MSA-10, MSA-11, MSA-31, Palmetto, and Raleigh. Grasses that had a dark, reddish purple-colored stigma included Floralawn, Floratam, and FL-1997-6.

This study probably will conclude at end of the fourth growing season in 1999. Thatch is becoming a serious problem which in turn is having a detrimental effect on turf quality.

Table 1. Rate of ground cover establishment of St. Augustinegrass selections and monthly ground cover estimates after planting on 8 August 1995 at Gainesville, FL.

Ground Cover

Entry Sept. Oct. Nov. Rate
Raleigh 26 31 33 46 a*
FL-1997-6 28 29 31 46 a
MSA-11 24 27 29 41 b
MSA-31

22 23 25 36 c
Palmetto 19 20 21 31 d
MSA-10 15 18 23 27 de
Floratam 12 17 21 24 e
Floralawn 12 16 21 23 ef
Floratine 9 14 18 19 fg
FHSA-115 9 12 15 17 g
FHSA-117 8 10 13 15 g
Seville 5 5 5 8 h
MSD 3 3 4 4

Cover rate is the sum of average monthly visual estimates from 8 August to 20 November 1995.

*Means with the same letter are not significantly different (P=0.05) using Waller-Duncan k-ratio t-test.

MSD=Minimum Significant Difference (P=0.05) between any two means within a column using Waller-Duncan k-ratio t-test. Each monthly value is an average of 16 observations. To determine statistical differences among grasses, subtract one grass mean from another grass mean within a column. Statistical differences occur when this value is larger than the corresponding MSD value for that column.

Table 2. Monthly and seasonal average ground cover estimates of St. Augustinegrass selections for the 1996 growing season at Gainesville, FL.

Ground cover

Entry April May June July Aug. Sept. Mean
%
Raleigh 41 52 81 92 93 97 76.1 a*
FL-1997-6 42 51 74 90 93 95 74.2 ab
MSA-11 41 46 73 85 88 96 71.4 a-c
Floratam 32 42 73 84 89 95 69.2 bc
MSA-10 34 41 69 83 87 93 67.8 c
Palmetto 35 42 69 82 87 91 67.8 c
MSA-31 34 42 64 80 86 92 66.5 cd
Floralawn 31 40 68 81 86 92 66.5 cd
Floratine 30 36 60 72 82 91 61.9 de
FHSA-115 27 34 57 73 81 88 59.8 e
FHSA-117 24 31 55 71 81 91 58.7 e
Seville 12 16 34 50 61 66 39.8 f
MSD 5 6 10 8 5 5 5.8

*Means with the same letter are not significantly different (P=0.05) using Waller-Duncan k-ratio t-test.

MSD=Minimum Significant Difference (P=0.05) between any two means within a column using Waller-Duncan k-ratio t-test. Each monthly value is an average of 16 observations. To determine statistical differences among grasses, subtract one grass mean from another grass mean within a column. Statistical differences occur when this value is larger than the corresponding MSD value for that column.

Table 3. Seasonal and average turf quality of St. Augustinegrass selections during the first growing season of 1996 at Gainesville, FL.

Season

Entry Summer Fall Mean CV
Rating %
MSA-31 8.2 7.2 7.6 a* 12.6
FHSA-117 6.6 6.1 6.3 b 12.4
MSA-11 7.1 5.8 6.3 b 18.3
Floratine 6.6 5.9 6.2 bc 17.7
Floratam 6.6 5.8 6.2 bc 18.1
FHSA-115 6.3 6.0 6.1 bc 14.7
FL-1997-6 6.7 5.4 5.9 b-d 19.2
Floralawn 6.4 5.5 5.9 b-d 21.0
Raleigh 6.0 5.0 5.4 b-d 19.9
Palmetto 5.9 4.8 5.2 cd 19.0
MSA-10 5.7 4.6 5.1 d 18.2
Seville 4.1 3.7 3.8 e 17.8
MSD§ 1.2 1.0 1.0 -


CV=Coefficient of Variation is a measure of relative variation around the seasonal mean expressed as a percentage.

Quality visually rated on a 1 to 9 scale where 9=best turf quality. Seasonal means are average of 64 observations.

*Means within columns followed by same letter are not significantly different (P=0.05) using Waller-Duncan k-ratio t-test.

§MSD=Minimum Significant Difference (P=0.05) between any two means within a column using Waller-Duncan k-ratio t-test. To determine statistical differences among grasses, subtract one grass mean from another grass mean within a column. Statistical differences (P=0.05) occur when this value is larger than the corresponding MSD value for that column.

Table 4. Seasonal and average turf density and color of St. Augustinegrass selections during the first growing season of 1996 at Gainesville, FL.

Density Color

Entry Summer Fall Mean Spring Summer Fall Mean
Rating
MSA-31 8.5 8.7 8.6 a* 7.9 6.7 5.8 6.6 ab
FL-1997-6 7.4 7.3 7.3 b 7.4 7.0 5.4 6.5 ab
MSA-11 7.8 7.0 7.2 bc 6.0 6.1 4.4 5.6 cd
FHSA-117 7.6 6.9 7.1 bc 7.9 7.1 6.7 7.1 a
Floratine 7.2 6.8 6.9 b-d 7.4 7.1 6.1 6.8 ab
FHSA-115 7.2 6.7 6.8 b-d 7.0 6.8 6.5 6.7 ab
Floratam 6.9 6.4 6.5 b-d 8.4 6.7 5.4 6.5 ab
Palmetto 6.9 6.3 6.4 cd 6.0 5.7 4.3 5.3 d
Raleigh 6.7 6.3 6.4 cd 5.6 5.8 4.3 5.3 d
Floralawn 6.9 6.2 6.4 cd 8.5 6.6 4.8 6.3 bc
MSA-10 6.9 6.0 6.2 d 7.0 5.9 4.2 5.5 d
Seville 5.3 5.2 5.3 e 4.8 5.4 5.0 5.2 d
MSD§ 0.8 0.9 0.8 1.0 0.9 0.7 0.7


Density and color visually rated on a 1 to 9 scale where 9=best turf density and dark, green color. Seasonal means are average of 40 and 120 observations, respectively.

*Means within columns followed by same letter are not significantly different (P=0.05) using Waller-Duncan k-ratio t-test.

§MSD=Minimum Significant Difference (P=0.05) between any two means within a column using Waller-Duncan k-ratio t-test. To determine statistical differences among grasses, subtract one grass mean from another grass mean within a column. Statistical differences (P=0.05) occur when this value is larger than the corresponding MSD value for that column.

Table 5. Seasonal and average turf quality of St. Augustinegrass selections during the second growing season of 1997 at Gainesville, FL.

Season

Entry Spring Summer Fall Winter Mean CV
Rating %
FL-1997-6 6.1 6.1 5.8 5.3 6.0 a* 11.7
Floratine 5.9 5.9 6.1 5.4 6.0 a 14.1
Floratam 6.0 5.5 6.0 5.5 5.7 a 19.5
MSA-31 5.8 5.7 5.6 5.7 5.6 ab 13.8
FHSA-117 5.8 5.7 5.4 4.8 5.5 a-c 16.8
FHSA-115 5.5 5.6 5.5 4.7 5.5 a-c 18.0
Floralawn 4.9 5.2 6.2 4.8 5.5 a-c 23.6
MSA-11 6.1 5.8 4.8 4.0 5.4 a-c 17.6
Palmetto 5.9 5.5 4.8 3.8 5.2 a-d 16.5
MSA-10 5.8 5.1 3.8 30 4.7 b-d 24.5
Raleigh 5.4 4.8 4.2 3.2 4.6 cd 20.6
Seville 4.8 4.7 4.0 2.2 4.3 d 28.3
MSD§ 0.9 1.7 1.1 1.3 1.0 -


CV=Coefficient of Variation is a measure of relative variation around the seasonal mean expressed as a percentage.

Quality visually rated on a 1 to 9 scale where 9=best turf quality. Seasonal means are average of 92 observations.

*Means within columns followed by same letter are not significantly different (P=0.05) using Waller-Duncan k-ratio t-test.

§MSD=Minimum Significant Difference (P=0.05) between any two means within a column using Waller-Duncan k-ratio t-test. To determine statistical differences among grasses, subtract one grass mean from another grass mean within a column. Statistical differences (P=0.05) occur when this value is larger than the corresponding MSD value for that column.

Table 6. Seasonal and average turf density and color of St. Augustinegrass selections during the second growing season of 1997 at Gainesville, FL.

Density Color

Entry Spring Summer Fall Winter Mean Spring Summer Fall Winter Mean
Rating
MSA-31 7.6 7.3 7.2 7.0 7.3 a* 2.5 3.5 4.5 5.8 4.1 b
FL-1997-6 7.2 7.3 7.0 7.6 7.2 a 5.9 5.6 6.1 5.2 5.8 a
MSA-11 7.8 7.3 6.9 6.9 7.1 ab 3.2 4.1 3.2 4.2 3.6 bc
Palmetto 7.1 6.6 6.2 6.6 6.6 bc 2.9 4.0 3.8 3.3 3.6 bc
Floratine 7.0 6.4 6.4 6.8 6.5 b-d 7.0 6.1 5.7 6.5 6.1 a
FHSA-117 6.9 6.4 6.5 6.4 6.5 b-d 7.0 6.2 5.8 6.2 6.2 a
MSA-10 7.2 6.0 5.9 6.5 6.2 c-e 3.0 3.6 3.2 2.7 3.2 c
FHSA-115 6.6 6.1 6.1 6.1 6.2 c-e 7.0 6.0 5.7 5.5 5.9 a
Raleigh 6.4 6.2 6.0 5.8 6.1 c-e 4.1 4.2 3.2 2.7 3.6 bc
Floratam 6.7 6.0 6.0 6.5 6.1 c-e 6.4 5.7 5.7 6.3 5.9 a
Floralawn 6.3 5.5 5.9 5.9 5.8 de 6.9 5.4 5.2 6.5 5.7 a
Seville 6.2 5.6 5.7 5.1 5.7 e 3.9 4.1 4.0 2.5 3.8 bc
MSD§ 1.1 0.9 0.8 0.7 0.7 1.2 1.1 1.0 1.7 0.7


Density and color visually rated on a 1 to 9 scale where 9=best turf density and dark, green color. Seasonal means are average of 84 and 44 observations, respectively.

*Means within columns followed by same letter are not significantly different (P=0.05) using Waller-Duncan k-ratio t-test.

§MSD=Minimum Significant Difference (P=0.05) between any two means within a column using Waller-Duncan k-ratio t-test. To determine statistical differences among grasses, subtract one grass mean from another grass mean within a column. Statistical differences (P=0.05) occur when this value is larger than the corresponding MSD value for that column.

Table 7. Seasonal and average turf quality of St. Augustinegrass selections during the third growing season of 1998 at Gainesville, FL.

Season

Entry Spring Summer Fall Mean CV
Rating %
FL-1997-6 7.0 7.4 5.4 6.9 a* 13.1
Floratine 6.4 6.3 4.2 5.9 b 16.0
FHSA-117 6.1 5.9 4.1 5.6 bc 15.5
MSA-11 5.9 6.1 3.8 5.6 bc 20.5
Palmetto 5.7 5.8 4.4 5.5 bc 14.8
FHSA-115 5.8 5.6 4.2 5.4 b-d 12.6
MSA-31 5.5 5.8 4.0 5.4 b-d 18.9
Floratam 5.6 5.6 4.2 5.3 b-d 13.6
Seville 4.8 5.6 4.6 5.3 b-d 11.0
Floralawn 5.5 5.4 3.8 5.1 b-d 16.5
MSA-10 4.4 5.4 3.6 4.8 cd 17.3
Raleigh 4.5 5.1 3.0 4.6 d 21.4
MSD§ 1.5 1.0 0.9 0.9 -


CV=Coefficient of Variation is a measure of relative variation around the seasonal mean expressed as a percentage.

Quality visually rated on a 1 to 9 scale where 9=best turf quality. Seasonal means are average of 40 observations.

*Means within columns followed by same letter are not significantly different (P=0.05) using Waller-Duncan k-ratio t-test.

§MSD=Minimum Significant Difference (P=0.05) between any two means within a column using Waller-Duncan k-ratio t-test. To determine statistical differences among grasses, subtract one grass mean from another grass mean within a column. Statistical differences (P=0.05) occur when this value is larger than the corresponding MSD value for that column.

Table 8. Seasonal and average turf density and color of St. Augustinegrass selections during the third growing season of 1998 at Gainesville, FL.

Density Color

Entry Spring Summer Fall Mean Spring Summer Fall Mean
Rating
FL-1997-6 7.3 7.9 6.4 7.2 a* 7.2 6.2 6.2 6.5 a
MSA-31 6.8 6.5 4.9 6.0 b 5.0 3.9 3.4 4.2 cd
MSA-11 6.2 6.6 4.9 5.9 b 5.7 3.5 2.8 4.1 cd
Palmetto 6.0 6.2 5.2 5.8 bc 5.8 3.4 2.7 4.0 cd
Floratine 6.0 6.2 5.1 5.8 bc 5.2 5.4 5.2 5.3 b
FHSA-117 6.1 6.1 4.9 5.7 b-d 5.2 5.5 5.3 5.4 b
FHSA-115 5.8 5.8 4.8 5.5 b-e 5.2 5.6 5.4 5.4 b
Seville 5.2 5.8 5.4 5.4 b-e 5.4 4.6 4.6 4.8 bc
MSA-10 4.8 6.0 4.8 5.3 b-e 5.1 3.5 3.0 4.0 cd
Floratam 5.4 5.3 4.7 5.1 c-e 4.7 5.0 4.6 4.8 bc
Floralawn 5.3 5.2 4.4 4.9 d-e 4.4 5.0 4.8 4.8 bc
Raleigh 5.0 5.4 4.2 4.8 e 4.4 3.5 2.9 3.7 d
MSD§ 1.4 0.9 0.6 0.8 1.3 0.8 0.9 0.9


Density and color visually rated on a 1 to 9 scale where 9=best turf density and dark, green color. Seasonal means are average of 40 and 40 observations, respectively.

*Means within columns followed by same letter are not significantly different (P=0.05) using Waller-Duncan k-ratio t-test.

§MSD=Minimum Significant Difference (P=0.05) between any two means within a column using Waller-Duncan k-ratio t-test. To determine statistical differences among grasses, subtract one grass mean from another grass mean within a column. Statistical differences (P=0.05) occur when this value is larger than the corresponding MSD value for that column.

Table 9. Comparative leaf texture, flowering characteristics, and Gray leaf spot susceptibility of St. Augustinegrass selections at Gainesville, FL.

Color

Entry Texture Seedheads Anther Stigma Gray leaf spot
Rating
MSA-10 6.8 a* 1.0 g 1.0 b 1.0 d 5.0 a
Raleigh 5.0 cd 1.6 fg 1.0 b 1.0 d 5.0 a
MSA-11 5.8 bc 1.9 ef 1.0 b 1.0 d 5.0 a
Palmetto 5.2 b-d 2.5 e 1.0 b 1.0 d 5.0 a
Floratine 4.5 de 3.6 d 3.0 a 4.0 b 2.8 b
FL-1997-6 6.0 ab 4.1 cd 3.0 a 5.0 a 5.0 a
FHSA-117 3.8 ef 4.2 b-d 3.0 a 4.0 b 1.8 c
Floratam 3.0 f 4.4 a-c 3.0 a 5.0 a 5.0 a
FHSA-115 5.0 cd 4.5 a-c 3.0 a 4.0 b 2.0 bc
Floralawn 3.0 f 4.5 a-c 3.0 a 5.0 a 4.5 a
MSA-31 6.0 ab 4.9 ab 1.0 b 1.0 d 5.0 a
Seville 5.5 bc 5.0 a 3.0 a 3.0 c 4.8 a


Texture visually rated on a 1 to 9 scale where 1=coarse and 9=fine leaf texture. Values are average of 4 observations. Seedheads visually rated on a scale of 1 to 5 where 1=most seedheads and 5=no seedheads. Values are average of 8 observations. Anther color visually rated on a scale of 1 to 3 where 1=yellow and 3=purple color. Values are average of 4 observations. Stigma color visually rated on a scale of 1 to 5 where 1=white, 3=pink, and 5=purple. Values are average of 8 observations. Gray leaf spot severity visually rated on a scale of 1=most infection and 5=no infection. Values are average of 4 observations.

*Means within columns with same letter are not significantly different (P=0.05) using Waller-Duncan k-ratio t-test.