Overseed Greens Performance Trial
D.M. Kopec Extension Turfgrass Specialist
J.J. Gilbert - Turfgrass Research Specialist
Thirteen overseed cool season grass species were evaluated for winter, spring and transition performance under greens conditions. Entries differed significantly for turfgrass color, quality, texture, uniformity and ball speed performances.
Greens performance is often a benchmark by which golf courses are evaluated. Bermudagrass greens are overseeded yearly in order to provide a putting surface from October to May or June in order to compensate for the dormant period characteristic of bermudagrass. The 1994-1995 overseed trials at the University of Arizona were conducted to assess the performance of overseed germplasm under greens conditions.
Materials and Methods
Thirteen overseed entries were included for testing on a four year old U.S.G.A specification green with Tifgreen (328) bermudagrass as the perennial surface. Plot size was 3' X 12', with each overseed entry appearing four times. Plots were seeded on October 12, 1994. Entries included either perennial ryegrass, creeping bentgrass, colonial bentgrass, Poa trivialis, or designated mixtures of these species. Entries were seeded at appropriate commercial rates for greens overseeding (Appendix Table 1). Plots were mowed eight times on October 27 from 3/4" to 1/4" and daily afterwards at 1/4". The test was then mowed 4X/week starting October 31, at 7mm with a 22" greens walking mower. On December 1, the mowing height was lowered to 6mm and mowed 4X weekly. On January 3 and 20, the mowing height was reduced to 5mm and 4mm respectively. The test was mowed 6X weekly at 4mm from January 20 until the close of the test. Plots were fertilized with granular formulations on 12 occasions between early November to June 19, 1995. A total of 4.9 lbs. of N, 4.6 lbs. of -P- and 3.7 lbs. of K were applied per 1000 ft2. There were seven additional applications of liquid Ferromec applied totalling 16 ounces of product/1000 ft2. Bayleton was applied at 8 ounces per acre on June 31, 1995 to suppress patch like symptoms on Poa trivialis plots. Oftanol was applied at the label rate for suppression of rove beetle activity on February 27. No topdressing occurred after initial overseeding. Plots were evaluated for establishment, turfgrass color, quality, density, texture, uniformity and percent bermuda at the end of the test. Ball speeds were measured on six dates by rolling three PING ZING 3 golf balls each in two directions immediately after plots were double mowed diagonally. The average distance of all six rolls was used in the analysis. All data was analyzed using the analysis of variance technique (ANOVA). Mean separation values were determined by using least significant difference (LSD) values, only when the overseed entry (treatment) effect was significant. The experiment was terminated on June 20, 1995.
Results and Discussion
As a greens surface, an overseed entry must be able to become established quickly to form a putting surface and accept foot and mower traffic. The percent plot cover estimates are visual estimates of the amount of grass cover (0-100% cover). Percent plot cover estimates were made on November 12 and November 23. On both dates, the amount of cover of the cool season overseed grass and the accompanying bermuda (on November 12 only) was affected by the overseed entry. On November 12, the amount of overseed visible ranged from 16% ('Winter Play PT') to 81% ('LRF Trans 2'). 'Cutter' ryegrass had 73% ryegrass cover. The bentgrasses and Poa trivialis entries ('Winter Play PT', 'J102 Bent', 'J100 Bent', 'PT #1') had between 16-25% cover from the overseed itself. When viewed with the underlying green bermudagrass ('Tifgreen'), the percent total plot cover increased. The rank order however between entries was essentially unchanged (Table 1).
By November 23, the bermudagrass was now dormant, and only the cool season grass was evaluated as the cover. Overseeded entries ranged from 43% ('J100 Bent') to 99% for the 'Brighstar/Winter Play' mixture. 'PT #1', and the 'Cypress PT/Trueline Bent' mixture produced ground cover faster than the bentgrasses alone (Table 1).
Turfgrass color due to overseeding entries was significant on all ten evaluation dates.
On October 22 (10 days after seeding) color scores before mowing ranged from 3.5 for the three bentgrasses, to 6.8 and 6.5 for 'LRF Trans 1' and "LRF AGRASS', respectively. 'Brighstar PR/Winter Play PT' and 'PT #1' were next with a mean color score of 6.3 (Table 2).
By November 2, color scores improved slightly after mowing, with entry means ranging from 3.0 ('J102 Bent') to 7.5 ('SRX 71-51'). 'LRF Trans 1' and 'Brighstar/Winter Play' had mean color scores of 6.8 and 6.3, respectively (Table 2).
By November 23, mean color scores ranged from 3.3 ('J102 Bent') to 6.3 for 'Brighstar/Winter Play' and 'LRF Trans 1'. In general, the bentgrass and Poa trivialis germplasm exhibited lighter color.
Warmer temperatures by January 30 and fertilization response increased color overall, with large differences detectable in the test. The three bentgrasses had now increased in color intensity and were almost as dark as 'LRF AGRASS'. The Poa trivialis germplasm was generally lighter in color than the other entries (Table 2).
At the end of February, warmer days and cool nights maximized the color expression and quality. The 'Cutter' perennial ryegrass was darkest (mean = 7.5), followed by 'J100', 'J101' and 'J102' bentgrasses. The 'LRF' grasses turned dark purple and did not respond to select applications of phosphorous, sulphur or calcium fertilizations (Table 2).
At the mid-March evaluation, 'Cutter' PR and the three bentgrasses still had the darkest color turf, followed by the Poa trivialis entries and finally, the 'LRF' grasses, which still remained purple in color (Table 3).
On April 15, the 'LRF AGRASS' was somewhat relieved of the purple color condition, while the 'LRF Trans 2' was very blotchy. 'Cutter' PR had the darkest color (6.5), followed by the 'LRF AGRASS', 'PT #1' and 'J101' and 'J100' bentgrasses (Table 3).
For the May 5 rating, mean color scores ranged from 4.8 ('LRF Trans 2' and 'LRF Trans 1') to 7.0 for 'Cutter' PR. 'LRF AGRASS' was next at 6.8, followed closely by 'PT #1' (6.3) and the now fully green bermudagrass check (6.0) (Table 3).
On June 6, color scores ranged from 4.5 ('J102 bent') to 7.0 for 'Cutter' PR, followed closely by the bermudagrass check (6.5) and 'PT #1' (6.0). The final color evaluation was made on June 20, 1995. The check had the darkest mean color (7.8) followed by 'Cutter' PR (which was now about 35% bermuda). The 'LRF Trans 1' and 'LRF Trans 2' had the lightest color and the least bermuda as well (Table 3).
The overall effect of overseed entries was significant on all nine evaluation dates for overall turfgrass quality.
Quality scores were first assigned to plots on November 2. Quality was slightly low due to the reduction in mowing height. Overseed scores ranged from 2.8 for 'Winter Play P.T.' to 7.0 for 'LRF Trans 2', followed by 6.0 mean scores for both 'Evening Shade PR/Cypress PT' and 'LRF Trans 1'. Both the bentgrass and Poa trivialis were slow to establish (lower quality scores) (Table 4).
By November 23, mean quality scores improved slightly from adapting to mowing stress and a light fertilization. Again both 'LRF Trans 2' and 'LRF Trans 1' had mean quality scores of 7.5, followed by 'Brighstar PR/Winter Play PT', 'LRF AGRASS' and 'Cutter PR'. The bentgrass entries were still slow in establishment, as was the 'PT #1' and 'Cypress/Trueline Bent' mixture (Table 4).
With the return of warmer weather, overall quality scores improved by January 30, 1995. 'Evening Shade/Cypress PT' and 'LRF Trans 2' had the highest mean quality scores of 7.5, followed by 'Winter Play PT' and 'Cypress/Trueline'. The 100% bentgrass entries were starting to improve in quality. Both 'LRF Trans 1' and 'LRF AGRASS' had quality scores of 3.0, due to the purple leaf color and splotchy appearance (Table 4).
With further increases in daytime temperatures and cool nights, ideal conditions were present for growing turf. On February 20, quality scores ranged from 3.3 ('LRF AGRASS') to 8.0 for 'LRF Trans 2'. By this time the 'PT #1' was matured and equal in performance to the 'Brighstar PR/Winter Play PT' mixture for quality. The 'Cutter' perennial ryegrass was still slightly ahead of the bentgrass entries for quality (Table 4).
The quality scores on March 18, 1995 ranged from 2.8 ('LRF AGRASS') to 7.3 for 'SRX 71-51'. The entries 'Cypress/Trueline', 'Cutter' and 'Brighstar/Winter Play' had mean quality scores of 7.0 (Table 5).
On April 15, mean quality for the overall test was very good and scores ranged from 4.8 ('LRF AGRASS') to 7.8 for both 'cypress/Trueline') and 'PT #1'. 'SRX 71-51' was next with 7.5. 'Cutter' PR, 'Eveningshade/Cypress PT/ and 'LRF Trans 1' were next with scores within the 7.3-7.5 performance range. The bentgrass entries scored within the 5.5-5.8 quality range (Table 5).
On May 5, the test was looking very good, as mean scores ranged from 4.5 to 8.0 with 'Cypress PT/Trueline Bent' having the highest numerical quality score (8.0). This was followed by 'Eveningshade PR/Cypress PT' (7.5) and 'SRX 71-51'. By now, the purple leaf condition of the 'LRF AGRASS' and 'LRF Trans 1' had become minimal. In general, those entries which had the least amount of bermudagrass present (such as 'Eveningshade/Cypress' and 'SRX 71-51') had the higher quality scores. The exception was the 'LRF' series, of which yielded moderate turf quality ('LRF Trans 1' and 'LRF Trans 2') compared to 'LRF AGRASS' which had low bermuda transition, but still low turf quality in the spring (Table 5).
The final quality scores were taken on June 6 (Table 5). Here overall quality would include total plot appearance and the incorporation of bermuda within the canopy. The 'Cutter' PR was tied for the highest numerical quality rating (7.3), which was about 32% ryegrass and 68% bermudagrass. 'LRF Trans 1' (also 7.3) had excellent quality, yet only had 9% bermuda underneath. In general, the bentgrasses had yielded to more bermudagrass than expected (46%-56%), but the differences in texture and growth habit made these plots less uniform than the Poa trivialis containing entries.
Uniformity was evaluated on seven dates, and is a reflection of consistency of cover, leaf texture, and uniform appearance within a plot. Uniformity reflects consistency. A 100% plot of crabgrass can have a high degree of uniformity, although its turf quality is not of high value. On all seven dates, the overseed entry (treatment) effect was significant, indicating true differences between entries for uniformity.
On November 23, uniformity scores ranged from 3.0 ('J102 Bent') to 7.3 for 'LRF Trans 2', followed closely by 'LRF Trans 1' (7.0). 'Brighstar/Winter Play' was next (6.8). The bentgrasses were less uniform, due to slower establishment, as anticipated (Table 6).
By January 30, six entries had mean uniformity ratings of 6.3 or greater. Both 'Eveningshade PR/Cypress PT' had a mean uniformity score of 7.5, followed closely by 'Winter Play PT' and 'LRF Trans 2' (7.3). The next three entries were either Poa trivialis as an overseed entry or contained it as a mixture component (Table 6).
On February 22, mean uniformity scores ranged from 3.8 to 7.3. 'LRF Trans 2' (7.3), 'PT #1' (6.8) and 'Brighstar/Eveningshade' (6.8) were the most uniform in appearance (Table 6).
By mid-March, some of the Poa trivialis germplasm had become quite uniform in appearance. 'PT #1' and 'Brighstar PR/Winter Play PT' had mean uniformity scores of 7.5 and 7.0, respectively. 'Cutter' PR and 'Cypress PT/Trueline Bent' and 'SRX 71-51' were next, each with a score of 6.8. 'LRF AGRASS' was non-uniform in appearance, due to a blotchy appearance and a purple leaf cast mixed within the canopy (Table 6).
Overall uniformity scores improved on April 15. Mean entry scores ranged from 3.8 to 7.8, with 'Cypress/Trueline' having the highest numerical uniformity score of 7.8. This was closely followed by 'SRX 71-51' and the 'Eveningshade/Cypress' mixture which had scores of 7.5 and 7.3, respectively (Table 6).
For the remaining two dates (May 5 and June 6), uniformity scores of 6.0 or greater either indicated a smooth transition to bermuda, and/or a consistency in retention of the cool season grass (Table 6).
Leaf texture is a visual assessment of leaf width and the predominant texture is scored for each plot. A plot with a mixture of diverse leaf widths would receive a score based on the predominate leaf width, but would receive a low uniformity score for this inconsistency. Leaf texture scores were assigned to plots on six dates during this test and on all dates the overseed (treatment) effect was significant.
On five of six dates, the 'LRF Trans 2' entry had the finest leaf texture, scoring mean values of 7.8 to 9.0. In the beginning of the test, (Nov. 23) all three 'LRF' grasses had very fine leaf texture mean scores, followed by the bentgrasses and Poa trivialis mixtures. By February 22, leaf texture (fineness) improved overall and scores improved over those in November (Table 7).
Once again, the Poa trivialis containing entries tended to have the finer leaf texture. 'LRF Trans 2' had the finest leaf texture (8.8). The same general trends occurred for leaf texture assessment on March 18, April 15, and May 5. 'LRF Trans 2' had the highest numerical score for leaf texture (8.8-9.0), which was followed closely by either 'PT #1', 'Cypress PT/Trueline Bent', or the 'Eveningshade PR/Cypress PT' blend (Table 7). The 'Cutter' PR showed maximum leaf expansion (although uniform in appearance and with acceptable quality) during the close of this test.
Density scores were assigned to plots on five evaluation dates, each of which had a significant overseeding (treatment) effect. The 'LRF Trans 2' entry had the most dense turf on all five dates. On February 22, 'PT #1' and 'Eveningshade/Cypress' had mean density scores of 7.0, followed by 'Cypress/Trueline Bent', 'Brighstar/Winter Play' and 'SRX 71-51' (6.0-6.8 range). The 'LRF AGRASS' density was noticeably decreased from the cessation of growth (Table 8).
On March 18, 'LRF Trans 2' had a mean density score of 8.0, followed by the 'Eveningshade/Cypress' blend at 7.0. 'Cypress/Trueline', 'PT #1', 'SRX 71-51', 'LRF Trans 1' and 'Winter Play PT' had mean scores of 6.5 to 6.8. There was little difference in visual density between 'Cutter' PR and the 'Brighstar/Winter Play' mixture (5.8 and 5.5 mean density scores, respectively) (Table 8).
On April 15, 'LRF Trans 2' had scored a mean density rating of 9.0, followed by 'LRF Trans 1' and 'Cypress PT/Trueline Bent' each with mean density values of 7.8. In general, the Poa trivialis material was finer in appearance than the bentgrass germplasm (Table 8).
By May 5, densities were at a maximum given long term (adequate) fertilization, and a cooler than average spring featuring bright sunny days. The same general trends in rank among entries occurred on May 5, as did previously on April 15 (Table 8).
At the close of the experiment, density values were generally high, with an inverse relationship occurring between the amount of bermuda visible in the plot and plot density values. Those entries with the most bermuda were the least dense visually (Tables 8, 10). The experiment was terminated in mid-June in preparation for a cultural management return to bermudagrass.
Turf Performance at Final Transition Evaluation
The percent plot bermuda, quality, color and density were assigned to plots on June 20 (final evaluation date). The non-overseed bermuda was 93% bermuda, while 'LRF Trans 1' and 'LRF Trans 2' were visibly less than 10% bermuda (Table 10). Surprisingly, the bentgrasses were around 50% bermudagrass, which was more than the Poa trivialis germplasm. For turfgrass quality, the 'Cutter' PR had the highest numerical quality score partly due to an even transition to bermuda and close match in color with the Tifgreen 328 bermuda. The bentgrasses were lowest in quality, due to extreme differences in leaf texture with the bermudagrass.
The same general trends occurred for the final color scores, with the noted change in rank between the 'LRF' series now being lighter in color than the bentgrass germplasm. The non-overseed bermudagrass and the 'Cutter' PR (which was now 68% bermudagrass) had the darkest colors at this time (Table 10).
For density, the 'LRF Trans 1', 'PT #1' and 'LRF Trans 2' entries were very dense, having mean density scores on June 6 of 8.0 or above (Table 10). The bermudagrass had the lowest visual density estimate (4.3). Visual density was inversely proportional (in part) to the amount of bermudagrass which was visible underneath (Table 10).
Seasonal Color and Quality Scores
Total season averages (mean for all evaluation dates) are provided in Table 11. For overall mean turfgrass color, 'Cutter' PR had the highest numerical score (6.6), followed by and the 'Brighstar PR/Winterplay PT' mixture, 'PT #1, and 'SRX 71-51'. The Poa trivialis and bentgrass germplasm is naturally lighter in color. For overall yearly quality, 'Eveningshade PR/Cypress Poa trivialis' and 'LRF Trans 2' (largely Poa trivialis) had overall mean quality scores of 6.8, followed by the 'Cypress PT/Trueline bentgrass' mixture (6.4) (Table 11). This was followed closely by the 'Cutter' PR (6.3), which had a dark green color and smoothest transition.
Ball speeds were taken in February, March, twice in April, and once again in both May and June. The overseed entry (treatment) effect was significant on all six evaluation dates. Ball speed test means ranged from 87" in May to 105" in April.
In February, the mean ball speed was 95", with entries ranging from 92-100 inches. The 'J100' bentgrass had the highest ball speed (100"), followed by the dormant bermudagrass. The LRF Transition 1 mixture was next, followed by SRX 71-51. The 'Eveningshade PR/Cypress P.T.' mixture was slowest with 92". A 10% difference occurred in ball speeds between entries based on this date.
For March, the overall mean ball speed for the entire test was again 95". 'LRF Transition 1', 'PT-1', 'LRF Trans 2' and the dormant bermuda had 97"-99" ball speeds.
In the beginning of April, the mean ball speed for the entire test was 99", with the dormant bermudagrass, 'LRF Trans 2', 'LRF AGRASS', 'Winter Play PT' and 'PT 1' having mean ball speeds of 100". Seven other entries had ball speeds of 97-99" performance. Cutter 'PR' had the slowest mean ball speed of 93".
By late April, ball speeds were at a maximum. The overall test mean was 105", and all entries had ball speeds of 100" or greater. The range among entries was from 100-110 inches. The dormant bermudagrass had the highest ball speed (110"), followed by 'LRF AGRASS', 'Cypress PT/Trueline bent', 'Winter Play P.T.', 'LRF Trans 2' and 'PT #1'. These grasses had mean ball speeds of 107" or greater. Both 'J101' and 'J102' bentgrasses had slightly better ball speeds than the 'Cutter' PR, although there was no significant mean difference between these three grasses.
By May, the accumulation of heat began to degrade the uniformity of the turf surface, causing mild irregular depressions in the turf. Mean ball speed performance was lowest (87") at this time. Entry performance means ranged from 82" ('SRX 71-51', 'J100 Bent') to 94" for 'PT #1'. The 'Cypress PT/Trueline Bent' and 'Winterplay PT' entries had slightly better ball speed performance than the bentgrass entries. At this time, the regrowth of the Tifgreen (328) caused a reduction in ball speed, due to increased resistance most likely caused from differences in texture between the overseed turf and the competing bermudagrass.
Ball speeds increased overall in June from the May rating. This may be due to a more uniform (but lower quality) and harder surface from repeated mowings during transition (rolling effect under grass decline). Entry ball speed mean performance ranged from 95" for 'Tifgreen' (328) bermudagrass, to 105" for 'PT #1' and the 'Eveningshade PR/Cypress P.T.' mixture. At this time, the 'LRF AGRASS' exhibited a ball speed performance similar to ryegrass. The experiment was terminated on June 20.
Appendix Table -A-
Overseed Greens Performance Trials
1994-1995 University of Arizona
ENTRY COMPOSITION RATE LBS./M APPEARS IN TABLES AS
1. 85% Eveningshade PR 35 lbs. 'EVSH.PR/CYP.PT'
15% Cypress Poa trivialis
2. 93-PT-1 Poa trivialis 6 lbs. 'PT #1'
3. 60% Cypress Poa trivialis 6 lbs. 'CYP/T.LINE BNT'
40% Trueline Bent
4. J101 Bentgrass 4 lbs. 'J101 BENT'
5. J100 Bentgrass 4 lbs. 'J100 BENT'
6. J102 Bentgrass 4 lbs. 'J102 BENT'
7. 15 lbs. Laser Poa trivialis 23 lbs. 'LRF TRANS 2'
8 lbs. H3 Composite
8. 20 lbs. Chewings Fescue 28 lbs. 'LRF TRANS 1'
8 lbs. H3 Composite
9. 8 lbs. LRF H3 Composite 16 lbs. 'LRF AGRASS'
10. Cutter PR 35 lbs. 'CUTTER PR'
11. SRX 71-51 PR 13 lbs. 'SRX 71-51'
10% SR7100 Colonial bent.
90% SR5100 Chewings Fescue
12. 90% Brighstar PR 25 lbs. 'B STAR/WNPLAY'
10% Winter Play Poa trivialis
13. Winter Play Poa trivialis 3 lbs. 'WNPLAY PT'
14. Non-overseeded bermuda -- 'CHECK'
Issued in furtherance of Cooperative Extension work, acts of May 8 and June 30, 1914, in cooperation with the U.S. Department of Agriculture, James A. Christenson, Director, Cooperative Extension, College of Agriculture & Life Sciences, The University of Arizona. The University of Arizona is an equal opportunity, affirmative action institution. The University does not discriminate on the basis of race, color, religion, sex, national origin, age, disability, veteran status, or sexual orientation in its programs and activities.