Poa trivialis (PT) was seeded at three rates (1.5 lb./M, 3.0 lb./M and 4.5 lb./M) and was compared to perennial ryegrass as overseeded turfs. Perennial ryegrass was seeded at 35 lb./M (standard greens rate).

Perennial ryegrass established ground cover quicker than PT. It took about four months for PT to establish 87% ground cover at 1.5 lb./M, while the 3.5/M and 4.5 lb./M rates produced 96% and 99% cover respectively at four months. Increased seeding rate increased ground cover and quality. Color was better at the 3.5/M and 4.5 lb./M rates up to February. After that, color was not greatly affected by seeding rate for PT.

Perennial ryegrass generally had better overall turfgrass quality scores than PT turfs. PT at the 4.5 lb./M rate had the best quality turf compared to PT at the other rates.PT at the 1.5 lb./M rate did not produce satisfactory quality for a putting green surface, while at the 3.0 lb./M rate, PT produced acceptable quality turf from February through May. Lower seed rates exhibited wider leaf blades and a more variable turf surface for PT.

The 4.5 lb./M rate seems the minimum for PT when seeded alone as a single species in an overseed situation for a sand based golf putting green.

Bermudagrass turf requires overseeding with a cool season grass in order to maintain a year round surface for golf. Bermudagrass greens can be overseeded with perennial ryegrass (Lolium perenne, creeping red fescue (Festuca rubra)) and more recently roughstalk bluegrass (Poa trivialis).

Poa trivialis (PT) contains approximately a two million seeds per lb., versus 225,000 - 250,000 seeds per lb. for perennial ryegrass. Seeding rates for establishing these grasses as permanent turfs in the cool regions of the United States usually range from 8-10 lbs./M (for perennial ryegrass) and from 1.0-2.0 lbs./M of Poa trivialis. Used as an overseed for putting greens surfaces, perennial ryegrass overseeding rates vary from 30-40 lbs./M. Poa trivialis overseed rates vary from 2.5 to 10 lbs./M in the literature. This represents a very great range in seed rates for PT. A seed rate trial was conducted at the University of Arizona Karsten Turfgrass Research Facility to test seeding rate effects of establishment and performance as an overseeded turf over Tifgreen bermudagrass maintained under greens conditions.

The Poa trivialis cultivar 'Sabre" was overseeded at 1.5, 3.0, and 4.5 lbs./M onto a four year old Tifgreen bermudagrass sand green which meets USGA specifications for rootzone and drainage requirements. The perennial ryegrass (blend Palmer II/Prelude II) was also seeded at 35 lbs./M. The bermudagrass was mowed at .1565 inches previously and was lightly verticut prior to overseeding. Plots were seeded in three directions and overseeded with 3/16"-1/4" of topdressing sand and rolled with a 600 lb. roller in one direction afterwards. Overseeding took place on October 7, 1994. Plots were replicated (along with an untreated check) three times in a RCBD. Plot size was 6'x8'. Plots were evaluated for various turfgrass responses to determine response and suitability under greens conditions. Plots were first mowed at a height of 7m (@ 3x/week) starting on 11/16/94, and then lowered to 6m (@ 3x/week) on 11/29/94, and then lowered to 5mm (@ 3x/week) 1/10/95, then lowered to 4m (@ 5x/week) on 1/20/95, then kept at 4mm (@ 6x/week) February 1, 1995. Plots received a total of 3.3, 2.6 and 2.4 lbs. per thousand square feet of N, P, K, respectively, from 14 fertilizations from October 20 to June 6. A total of fifteen ounces of Ferromec were also applied on five dates as well. The green was irrigated with 80% of the AZMET RefETo from the on site weather station.

Plots were evaluated for initial ground cover on November 8 and on December 20. On November 8, the entire amount of turf was evaluated, while on December 20, only the amount of the cool season grass was scored, as the bermuda was then completely dormant.

November 11, 1994
On November 11, 1994, the perennial ryegrass plots had established a commanding lead in percent plot cover, providing 97% mean ground cover, followed by PT at 58%, 37% and 18% at 4.5, 3.0 and at the 1.5 lb./M rate, respectively. The seed rate effect for PT was linear and statistically significant (Table 1).

November 23, 1994
Percent plot cover scores ranged from 100% for perennial ryegrass, to 33% for PT at the 1.5 lb. rate. PT at 3.0 and 4.5 lb./M rates had mean percent plot cover scores of 53% and 73%, respectively (Table 1).

December 12, 1994
The amount of plot cover among overseed plots ranged from 100% for perennial ryegrass, to 30% for the PT at the 1.5 lb. rate. The check had 8% cool season turf (either as a perennial overseed, or from dormant seed). PT at 4.5 lbs./M had 87% cover, while the 3.0 lb. and 1.5 lb. rates had 64% and 30% mean plot coverage (Table 1).

Color scores were assigned to all plots using a visual scale of 1-9, where 1 = dead turf on straw, and 9 = very dark. On December 20, mean turfgrass color scores ranged from 4.0 to 6.0, with ryegrass having a moderately green color (Table 2). PT is typically light green in color, as is normal for the cultivar "Sabre". PT mean color scores ranged from 4.0 to 4.3, regardless of seeding rate.

Turfgrass quality scores were also assigned at this time, using a visual scale of 1-9, where 1 = dead, 9 = best. Quality mean scores ranged from 2.7 for PT at 1.5 lb./M to 8.0 for perennial ryegrass at the standard rate of 35 lb./M. PT at 4.5 lb./M had a mean quality score of 5.0, which is minimally acceptable for a green (Table 3). The quality scores for PT were positively linear with seed rate.

January 30, 1995
Color scores were essentially identical between all overseeded plots regardless of seeding rate of PT and the species (PT vs. ryegrass). All plots had mean scores of 6.0 (Table 2).

Turfgrass scores for overall turfgrass quality ranged from 2.7 to 7.0 for the overseeded turf (Table 3). Perennial ryegrass had a mean color score of 7.0, followed by PT at the 4.5 lb./rate (mean = 5.3). PT at the 3.0 lb. and 1.5 lb. seeding rate produced quality scores of 4.3 and 2.7 respectively at this time. These scores represent less than acceptable greens quality. Mean plot coverage scores ranged from 99% (perennial ryegrass) to 75% for PT at the lowest seed rate of 1.5 lb./M. PT at 4.5 lb./M produced a mean percent plot cover of 93%, followed by PT at 1.5 lb./M (75%) (Table 1).

February 20, 1995
Mean turfgrass color scores ranged from 4.3 to 6.3, with perennial ryegrass having the best color. The color response was essentially the same among PT seed rates (4.3 to 5.0) (Table 2).

Quality scores on February 20 ranged from 7.7 (perennial ryegrass) to 3.3 for the PT at the lowest seed rate of 1.5 lb./M. The PT at 4.5 lb. and the 3.0 lb./M rates were not statistically different from each other (5.7 and 5.0, respectively) (Table 3).

Percent plot cover of overseed was increased. PT at the 3.0 and 4.5 lb. rates averaged 96-99% coverage, while the 1.5 lb. rate was 87%. Perennial ryegrass provided again 100% cover (Table 1).

March 7, 1995
Turfgrass visual density scores were assigned to plots on March 7, using a 1-9 scale, where 1 = no turf, 9 = most dense. Mean density scores ranged from 8.7 (ryegrass) to 3.7 for PT at the low rate (Table 5). Visual density increased with increased seeding rate for PT. The 4.5 lb./M rate had a visual density mean score of 7.0, followed by a score of 5.7 for the 3.0 lb./M rate.

Mean color scores ranged from 5.7 to 7.0 among overseeded turf (Table 2). The perennial ryegrass had the darkest color (as expected). At this time, the PT at the low seeding rate (1.5 lb./M) had the best color among PT seed rate treatments. In the spring, PT produces and/or has its stolons elongate profusely, and perhaps the lower seeding rate PT had better color from less intra-plot competition at this time.

However, mean turfgrass quality scores showed the opposite response, as PT at the highest seeding rate had the best color among PT plots (Table 3). PT at the 1.5 lb. rate did not produce adequate turf quality at five months after seeding, while the 3.0 lb. rate produced acceptable quality turf.

Texture scores were assigned using a visual scale of 1-9, 1 = crabgrass size (coarse) leafs, 9 = extremely fine. The higher seed rates of PT produced the finer leaf textures. The ryegrass still had the finest leaf texture from the 35 lb./M seed rate, although PT at the 4.5 lb. rate was very similar in texture (Table 4).

April 8, 1995
Color scores for the ryegrass began to decrease, as longer day lengths returned. The mean response for ryegrass was 6.7, while PT ranged from 4.7 to 5.3 across all three seed rates. The non-overseeded bermudagrass check was now showing some signs of green-up and scored a mean color value of 2.0 (Table 2).

Mean overall turfgrass quality scores ranged from 3.7 to 7.3, with ryegrass having the highest quality score. The 1.5 lb. rate of PT did not exhibit acceptable quality as you would expect on a green (Table 3).

Mean visual density scores ranged from 4.6 to 8.0. For the first time, the high rate of PT (4.5 lb./M) was denser visually than the ryegrass at 3.5 lb./M. However, this difference was not significant (Table 5).

Uniformity scores were assigned visually on a scale of 1-9, where 1 = least, 9 = most uniform. Uniformity assessments include consistency of leaf texture and/or a stemy appearance in the plot, as well as color consistency (blotchyness and stemy turf are often common in the spring). Ryegrass and PT at the 4.5 lb./M had identical uniformity scores of 7.0. The 1.5 lb./M rate of PT was not very uniform, as leaf blades were highly variable (Table 4).

Texture scores were again given on April 8. As before, leaf texture scores increased with increased seed rate for PT. Mean texture scores for the two highest PT rates and for the ryegrass were statistically similar, with treatment means ranging from 4.7 to 8.3. This demonstrated the highly variable nature of texture expression in the spring. The low rate of PT had a mean value of 4.7, as leaf widths were wider (visual assessment) at the low seeding rate of 1.5 lb./M (Table 4).

May 8, 1995
Mean color scores were starting to decrease with the arrival of increased daytime temperatures. Mean color scores ranged from 2.3 (bermudagrass) to 6.3 for perennial ryegrass. The PT plots ranged in mean scores from 4.7 to 5.7 (Table 2).

Turfgrass quality mean scores ranged from 3.3 to 7.7, with ryegrass and PT at the 4.5 lb./M rate having similar mean quality responses (7.7 and 7.0, respectively). The 3.0 lb./M rate of PT had an above level of acceptable quality (mean = 6.3) followed by PT at 1.5 lb./M (mean = 5.3). The bermudagrass now had a mean quality score of 3.3 (Table 3).

Density scores were assigned on May 8 as well. The perennial ryegrass turf still had high visual density scores, which were identical to the PT at the 4.5 lb./M rate (means = 7.7). PT at the 3.0 lb./M rate was next with a mean density score of 6.7 lb./M. The bermudagrass check was sparse at 2.3 (Table 5).

Texture scores were now closer among overseeded turfs on this green. Mean treatment scores ranged from 5.3 to 7.7. The PT at 4.5 lb./M had the largest numerical mean score for texture (fine leaves), with a value of 7.7. This was followed closely by the ryegrass and PT at the 1.5 lb./M rate (means = 7.0) (Table 4).

Final uniformity scores were taken on May 8, as scores ranged from 3.3 to 8.0. The perennial ryegrass turf was the most uniform (visually) with a mean value of 8.0. This was followed closely by PT at the high rate (4.5 lb./M) which had a mean uniformity of 7.0 (Table 4). The return of bermuda into the overseed turf is more visible (in terms of leaf texture differences) in PT, than that of perennial ryegrass. This probably is reflected in the ratings. This test was terminated on May 8, as management practices were now being conducted across these plots to determine the effects of cultural management on transition of PT at these seed rates.

FN:SRPOATRV.95 DIR:Q196

Table 1. Turfgrass establishment and percent plot overseed of Tifgreen Bermudagrass overseeded fall 1994. University of Arizona.

Percent Plot Cover1

Percent Cool Season Turf2

Treatment3	Rate4	11/08	11/23	Treatment	Rate	12/20	01/30	02/20
PR	35	97	100	PR	35	100	99	100
PT	1.5	18	33	PT	1.5	30	75	87
PT	3.0	37	53	PT	3.0	64	88	96
PT	4.5	59	73	PT	1.5	87	93	99
CHECK	--	0	0	CHECK	--	8
TEST MEAN5		42	52			58	71	76
LSD VALUE6		7	6			17	4	8

¹Percent plot cover (0-100%) of all existing turf, may include some bermudagrass, if present. Values are means of three replications.

²Percent plot cover (0-100%) of cool season turf, no bermudagrass present. Values are means of three replications.

³Seed treatments. PR = perennial ryegrass, PT = Poa trivialis.

⁴Seed rates expressed as lbs./1000 ft².

⁵Test mean = mean of all plots on each evaluation date.

⁶LSD value = LSD statistic. Treatment means with differences greater than the LSD value are statistically different from each other.

Table 2. Mean turfgrass color¹ scores of overseeded Tifgreen bermudagrass overseeded fall 1994. University of Arizona.

TREATMENT2	RATE3	12/20/94	01/30/95	02/20/95	03/07/95	04/08/95	05/08/95
PR	35	6.0	6.0	6.3	7.0	6.7	6.3
PT	1.5	4.0	6.0	4.7	6.0	4.7	4.7
PT	3.0	4.3	6.0	4.3	5.7	5.3	5.7
PT	4.5	4.0	6.0	5.0	5.7	5.0	5.3
CHECK	--	2.0	1.0	1.0	1.0	2.0	2.3
TEST MEAN4		4.1	5.0	4.3	6.1	4.7	4.9
LSD VALUE5		0.9	--	0.9	1.1	0.7	1.4

¹Color scores (1-9), 1 = straw, 9 = dark green. Values are means of three replications.

²Seed treatments. PR = perennial ryegrass, PT = Poa trivialis.

³Seed rates expressed as lbs./1000 ft².

⁴Test mean = mean of all plots on each evaluation date.

⁵LSD value = LSD statistic. Treatment means with differences greater than the LSD value are statistically different from each other.

Table 3. Mean turfgrass quality¹ scores of overseeded Tifgreen bermudagrass overseeded fall 1994. University of Arizona.

TREATMENT2	RATE3	12/20/94	01/30/95	02/20/95	03/07/95	04/08/95	05/08/95
PR	35	8.0	7.0	7.7	8.0	7.3	7.7
PT	1.5	2.7	2.7	3.3	4.0	3.7	5.3
PT	3.0	4.0	4.3	5.0	5.3	5.3	6.3
PT	4.5	5.0	5.3	5.6	6.7	5.7	7.0
CHECK	--	1.0	1.0	1.0	1.0	1.7	3.3
TEST MEAN4		4.3	4.1	4.5	5.0	4.8	5.9
LSD VALUE5		1.2	0.7	0.9	0.6	1.2	1.0

¹Quality scores (1-9), 1 = straw, 9 = dark green. Values are means of three replications.

²Seed treatments. PR = perennial ryegrass, PT = Poa trivialis.

³Seed rates expressed as lbs./1000 ft².

⁴Test mean = mean of all plots on each evaluation date.

⁵LSD value = LSD statistic. Treatment means with differences greater than the LSD value are statistically different from each other.

Table 4. Mean turfgrass texture¹ and uniformity² scores of overseeded Tifgreen bermudagrass. University of Arizona.

TEXTURE

UNIFORMITY

Treatment3	Rate4	03/07/95	04/08/95	05/08/95	Treatment	Rate	04/08/95	05/08/95
PR	35	8.3	8.3	7.0	PR	35	7.0	8.0
PT	1.5	4.7	4.7	5.3	PT	1.5	3.7	4.7
PT	3.0	6.7	6.7	7.0	PT	3.0	5.7	6.0
PT	4.5	7.3	7.3	7.7	PT	4.5	7.0	7.0
CHECK	--	1.0	2.0	3.3	CHECK	--	2.0	3.3
TEST MEAN5		5.6	5.8	6.1	TEST MEAN		5.1	5.8
LSD VALUE6		0.8	1.9	1.7	LSD VALUE		1.9	1.6

¹Turfgrass texture scores 1-9. 1 = coarse, 9 = fine. Values are means of three replications.

²Turfgrass uniformity scores 1-9. 1 = poor, 9 = best. Values are means of three replications.

³Seed treatments. PR = perennial ryegrass, PT = Poa trivialis.

⁴Seed rates expressed as lbs./1000 ft².

⁵Test mean = mean of all plots on each evaluation date.

⁶LSD value = LSD statistic. Treatment means with differences greater than the LSD value are statistically different from each other.

Table 5. Mean turfgrass density¹ scores of overseeded Tifgreen bermudagrass. University of Arizona 1994-1995.

TREATMENT2	RATE3	03/07/95	04/08/95	05/08/95
PR	35	8.7	7.0	7.7
PT	1.5	3.7	3.7	4.7
PT	3.0	5.7	5.7	6.0
PT	4.5	7.0	7.3	7.7
CHECK	--	1.0	2.0	2.3
TEST MEAN4		5.2	5.9	5.8
LSD VALUE5		1.1	1.2	1.7

¹Turfgrass density scores 1-9. 1 = no turf, 9 = very dense. Values are means of three replications.

²Seed treatments. PR = perennial ryegrass, PT = Poa trivialis.

³Seed rates expressed as lbs./1000 ft².

⁴Test mean = mean of all plots on each evaluation date.

⁵LSD value = LSD statistic. Treatment means with differences greater than the LSD value are statistically different from each other.