Principal Investigator: Bob Mugaas, Extension Educator Horticulture, University of Minnesota Extension.

Transcription

1 Low Maintenance Turfgrass Evaluation Study A cooperative project between the University of Minnesota Extension and Hennepin County Environmental Services Principal Investigator: Bob Mugaas, Extension Educator Horticulture, University of Minnesota Extension. Project Managers: Anthony Brough and Greg Senst, Department of Environmental Services, Hennepin County. Installation Date: April 25, Location: Spring Park, MN. The study plots are located on the south facing slope between the Lake Minnetonka Sheriff s Water Patrol (SWP) and the Spring Park public access (PA) boat ramp. Nature and Purpose of the Study: Following several unsuccessful attempts to establish permanent, perennial vegetation on this exposed south facing shoreline embankment on Lake Minnetonka, the Hennepin County Environmental Services Department contacted the University of Minnesota Extension for advice and possible assistance in attempting to establish a very low maintenance grassy type groundcover on this area. From that request evolved a project whereby a commercially available no-mow mix would be used along with separate plantings of each of the species/cultivars in the mix. In addition a seeded and sodded example of tall fescue would also be evaluated. The specific cultivars for both the no-mow mix and the tall fescues are noted below in the Treatment section. With the exception of the sodded tall fescue cultivar, all other varieties were direct seeded April 25, Evaluation of the plots included both pictures and notes regarding establishment success, as well as color, density and overall quality of the planting as observed at various times during 2006 and Ultimately, information regarding the establishment, longevity and competitiveness of fine and tall fescues on very difficult sites will be obtained and helpful to others considering use of the same plant material in similar situations. In addition, the fact that individual fine fescue varieties could be evaluated independently as well as when blended together made it easier to asses their individual performance and potential contribution to the success of this or any other blend where they might be included. Turfgrass Evaluation Plots: Plot sizes were somewhat variable due to the irregularity of the site. Hence, the largest plot was located to the west of the existing wood chip path closest to the SWP. The smallest plot is located on the far eastern side of the site closest to the PA. The five plots in between were all about 20 feet wide but variable in depth due to shrub plantings on the north end of the area along with scattered small trees. (Pictures 1-4)

2 Seeding Rates: All fine fescues and no-mow mix were seeded at the rate of five pounds per one thousand square feet. The tall fescue blend was seeded at the rate of seven pounds per one thousand square feet. Site preparation: All areas were treated with the herbicide Round-up one week before seeding primarily to eliminate any perennial weeds and early germinating annual weeds. Seeding: On the day of seeding, April 25, 2006, the soil surface was scarified using a vertical mower such that at least the top ½ inch of soil was loose and would allow for easy incorporation of the seed into the soil. Seeding was accomplished using an older model Scott s drop spreader and done in two directions to help ensure better seed distribution. Following seeding, all plots were lightly raked thereby incorporating seed into the loose surface soil. Futerra mats were immediately placed over the seeded areas to help minimize erosion and provide for a more uniform germination environment. Treatments (species and cultivars): Plot descriptions are from west (toward SWP) to east (toward PA) beginning at the west side with plot number one. Plot 1: Larger plot seeded with Twin City Seed No-Mow mix. Species/varieties included: Sheep fescue (Variety Not Stated (VNS)) Hard fescue Defiant Creeping red fescue Celestial Chewings fescue Intrigue Plot 2: Plot on east side of wood chip path adjacent to No-Mow mix Fine fescue cultivar: sheep fescue (VNS) Plot 3: (east of 2) Fine fescue cultivar: Defiant Plot 4: (east of 3) Fine fescue cultivar: Celestial Plot 5: (east of 4) Fine fescue cultivar: Intrigue Plot 6: (east of 5) Seeded tall fescue blend: Cultivars included: Millennium (32.64%) Aztec II (tall fescue blend) (32.64%) Anthem II (32.64%) Plot 7: (east of 6) Smallest plot closest to PA with crabapple tree located on the far eastern end of the plots. This area was sodded with Rhizomatous Tall Fescue (RTF) donated by Rehbein Sod Farms. Installation date for this sod was May 9, Post-installation care: Due to the very hot dry conditions during spring and early summer of 2006, regular watering was essential to ensure adequate moisture for

3 germination and early seedling growth. As this was a spring seeding, the potential for annual weeds to germinate, grow and potentially outgrow and out-compete the desirable grasses was high. Hence, regular mowing was carried out through about the middle of August, 2006 as a means of providing some level of weed suppression without the need for herbicide application during persistently hot dry conditions during this period. Following an application of a broadleaf herbicide later in the season of 2006 to control primarily developing perennial broadleaf weeds, no additional herbicides for either annual or perennial weeds were used in Even though this was to be a no-mow area, the diligent attention paid to watering and early mowing did result in acceptable or better establishment of all grass types and is a practice that should be considered when doing similar spring seeding projects and the high potential for annual weed infestation. Plots did receive an application of nitrogen fertilizer at the rate of 1 pound of N per 1000 square feet in late October of both 2006 and Results and Discussion Seedling emergence and early establishment (Table 1.) At two weeks past initial seeding, the chewings fescue variety Intrigue ranked highest in emergence quantity and quality compared to all other seeded varieties. The NM-Mix, sheep fescue and Celestial creeping red fescue tied for next best turfgrass emergence quantity and quality while Defiant hard fescue and the TF-Blend were barely beginning to emerge through the Futerra mats. See Pictures 5-7. By four weeks past initial seeding, all cultivars had emerged and began to cover the soil surface. This is evidenced by the turfgrass quality ratings in Table 4 where all cultivars including the NM-mix and TF-Blend had reached acceptable turfgrass quality with only Defiant lagging somewhat behind. Turfgrass quality ratings are an overall reflection of how the plots are looking and growing and is directly influenced by both color and density characteristics. See Pictures The TF-RTF was installed via sod on the 9 th of May and ranked very high in color, density and turfgrass quality at two weeks past its installation. This is most likely a reflection of its sod field characteristics as it would not have had time to exhibit the potential growth limitations and stresses imposed by this particular site. See Pictures 8, 13. Turfgrass color, density and overall quality (Tables 2, 3 and 4.) No-Mow Mix and individual fine fescue varieties. At this particular site, the back or upper half (northern end) of the individual variety plots were at least partially shaded for most of the day from small trees and/or the lilac hedge running along the curb line at the back (north edge) of the plots. In those partially shaded areas, most of the fine fescue varieties retained acceptable color, density and quality characteristics throughout the hot dry periods of 2006 and particularly 2007 even though no supplemental irrigation was being provided that year, (data not shown). See Pictures As you can see in Pictures 21-26, the individual fine fescue characteristics were

4 all much lower on the lower (southern) third to half of the plots. Color, density and turfgrass quality ratings shown in this report reflect how well the individual cultivars performed when not afforded the protection of partially shaded conditions. Most of the NM-Mix area was exposed to full sun conditions throughout the day and that plot performed more like the southern portions of the individual variety plots. Again, a notable exception was the shade shadow area provided by a small crabapple tree on the southeast corner of that plot. Similar to the protected areas of the individual variety plots, that partially shaded area was better in all characteristics than the open exposed areas. See Picture 26. Like the individual fine fescue varieties, this report reflects performance of the NM-Mix outside of the partially protected area. After the August 9, 2007 ratings, Pictures 32-37, weather patterns changed from hot and dry to an extremely wet and stormy period lasting through much of September. At the August 31, 2007 rating date, Pictures 38-43, partial recovery is already evident even though there did appear to be rather large areas where permanent injury had occurred. With the late summer rains and subsequently cooler temperatures all plots with the exception of the sheep fescue had returned to acceptable color by October 11, 2007 or 72 days after the August 9, 2007 rating date. See pictures However, substantial permanent injury to the individual fine fescue varieties as well as the NM-Mix was evident by that October date and is reflected in the lower ratings for density and turfgrass quality compared to their May 15, 2007 values. See pictures and Thus, even though color may have returned to being acceptable, the two important characteristics of density and turfgrass quality relative soil erosion protection and weed encroachment were unacceptable for the NM-Mix as well as all individual fine fescue varieties. Permanent injury to the NM-Mix and individual fine fescue varieties was still evident by April of 2008 with all plots barely above the lowest designations for both density and turfgrass quality. See Pictures However, by June 30, 2008 all were showing acceptable color. See Pictures With the exception of Intrigue and Celestial, the NM-Mix along with the sheep fescue and Defiant had improved considerably in both density and turfgrass quality to the point that the NM-Mix had reached acceptable turfgrass quality. It is quite likely that the cooler and wetter conditions of spring 2008 allowed for greater recovery and growth. With the advent of warmer and drier conditions since the middle of June, 2008 it will be interesting to observe how well those plants will continue to survive. It was also interesting to observe the significantly greater amount of flowering culm production there was on the NM-Mix and individual fine fescue varieties in the sunny areas compared to the shaded areas. See Pictures 58, 59 and 62. It is quite apparent that exposure to greater sunlight with more moderate weather conditions resulted in greater flower production; a typical characteristic exhibited by most flowering plants.

5 It is generally considered that the fine fescues have very good drought tolerance but only average high temperature tolerance. The observations from this study would also support those findings. That is, presumably the level of dryness would be similar throughout the plots but the partially shaded conditions would keep temperatures slightly lower therefore providing just enough relief from high temperatures that the grasses would survive and continue growing when more favorable growing conditions returned later in the summer. While both sheep and hard fescue are known for their tolerance to hot and dry conditions, the severity of those conditions during the summer of 2007 did result in significant permanent injury in the sunny, exposed areas of the plots. However, both the sheep and hard fescues had made slightly more improvement in turfgrass density and overall quality compared to the creeping red and chewings fescue varieties by the end of Further improvement was observed in those same two characteristics by June 30 of Again, both hard and sheep fescue showed greater improvement than either the creeping or chewings cultivars. Further evaluation on the use of fine fescues in similar harsh sites would help further clarify their stress tolerance levels as well as helping to shed light on their limits of use and adaptation in these kinds of sites. Tall fescue blend and RTF sod The two tall fescue plots are both in full sun conditions for most of the day. However, while they did exhibit significant browning during the dry period in 2007, (Pictures 36 and 37), their recovery was much quicker with little to no permanent injury exhibited in any portion of the plots even in the southern most areas. See pictures 42, 43, 48 and 49. Even by 22 days after the onset of the summer rainy period that began on August 10, both tall fescue plots had returned to acceptable levels of color, and overall turfgrass quality. See Pictures 42 and 43. By the October rating date, 72 days after August 10, both plots were at or above acceptable levels for all three characteristics. See Pictures 48 and 49. By April of 2008, the density level of the TF Blend was at an acceptable rating while the color and overall turfgrass quality characteristics were below acceptable levels. See Pictures 55 and 63. By June 30, 2008 the TF-Blend was at acceptable levels for all three characteristics. The TF-RTF exhibited acceptable levels for all three characteristics for that same time period. See pictures 56 and 64. Given the harshness of the growing conditions at this site, the two tall fescue plots performed exceptionally well. While much of their foliage was brown during the hot, dry conditions of 2007, their recovery to good color and overall turfgrass quality along with the ability to retain good turfgrass density throughout that period are very positive characteristics. In addition, there appears to be very little winter injury in either of the plots in spite of little winter protection from either mulches or snow. These characteristics would be a definite plus when considering their use in this area. Further trial and evaluation of tall fescues should help further refine their tolerances and adaptations to equally difficult sites.

6 Percent Weed Cover (Table 5) No-Mow Mix and Fine Fescue Varieties The primary weeds of this site are broadleaf annuals and annual weedy grasses. Percent weed cover was visually estimated and refers to the amount or presence of weeds throughout the site. In many instances, the annual weeds were scattered among the grass plants but had not necessarily displaced them. Hence, a high percent weed cover rating reflects a plot where weeds could be found throughout the area but not necessarily displacing the grass plants. The establishment year, 2006, saw the greatest amount of weed cover on the plots. See Pictures It is interesting to note that the lowest percentage was recorded for the variety Intrigue, which germinated quickly and began to cover the soil surface most rapidly. See Picture 20. Hence, that observation would support the notion that good germination percentage and good seedling vigor can be a way for grasses to out compete annual weeds especially when doing spring seeding. Mowing was performed on a regular basis during May, June, July and early August of 2006 as one means of helping to minimize the negative impacts of weed competition with the turfgrasses. No mowing was done during the 2007 growing season nor is any mowing currently planned for 2008 season. A single mowing, either in the fall of 2008 or spring of 2009 may be considered. Following the establishment year and the use of a broadleaf herbicide later in the 2006 season, weed population levels dropped significantly and remained fairly constant or slightly increased over the 2007 growing season. That population level remained nearly the same from the last rating date in 2007 through the spring of Again, the southern end of the plots saw the greatest amount of weed infestation as this was typically the area that had lost the most plant material due to the summer heat and drought stresses. See Pictures Between poor turfgrass density and the bright, sunny conditions of those areas, there was little turfgrass shading or competition to limit the amount of weed germination and seedling growth. Weed populations were much less in the partially shaded areas presumably due to the denser turfgrass cover and lower light conditions necessary for weed seed germination. See Picture 47. Tall fescue blend and RTF sod Perhaps one of the more interesting observations of this study was the lack of weed development occurring in either of the tall fescue plots, but in particular the seeded tall fescue plot. While percent of annual weed cover increased over the 2006 growing season, it dropped back to less than 10 percent by May of 2007 and remained at or less than 10% the remainder of the study. Since, the southern portions of the plot did not see the same amount of permanent injury as those of the fine fescues, there remained a sufficient turfgrass cover to presumably prevent the establishment of new weed seedlings. Initially, it is easier to understand why the RTF sodded plots had little to no weed infestation due to the density and vigorous growth of the sod. However, like the seeded

7 plot, there was never more than 10% weed infestation during the study even after coming out of the severe heat and drought conditions of May, June and July of 2007 when density and turfgrass quality ratings were very low for both tall fescue plots. See Pictures 42 and 43. During that time, in both the seeded and sodded plots, lots of the grass plant foliage had fallen over forming a rather dense cover over the soil surface presumably limiting the amount of light reaching the surface thereby limiting the amount of weed seed germination. See Pictures 36 and 37. Since both plots recovered fairly quickly following the adverse weather conditions and being relatively late in the growing season there may not have been ample time or opportunity for weeds to germinate and become established. See Pictures 48, 49, 63 and 64. Hence, these two plots had weed infestation levels at or below 10% during the entire course study. It will be interesting to observe whether that trend will continue over the next couple of seasons. Combined with its tolerance to very harsh environmental conditions and apparent ability to successfully outcompete weedy plants especially early in the establishment period, tall fescues could be a good choice for very low maintenance areas and require little, if any, herbicide intervention during the establishment process to minimize weed competition. Summary: Given the harsh conditions of poor soils and extreme exposure of this site, the fine fescues under a no-mow situation could be a good choice for providing soil stabilization and an appealing look to an area. However, in full sun exposure during periods of high temperatures and dry conditions, enough permanent injury may occur that additional overseeding may be needed in order to preserve turfgrass density and limit weed encroachment. The use of Futerra mats provided good protection from soil erosion and likely contributed to better initial establishment through greater uniformity of conditions in the immediate seed germinating environment. Supplemental irrigation can be extremely important in the early growth, establishment and even survival of spring seeded turfgrass. It can also be a means of moderating the effects of high temperatures. In this instance, the consistent watering provided by Hennepin County staff allowed for relatively uniform germination and early growth of the seedlings thereby getting them off to as good a start as possible given the prevailing hot, dry conditions during this late spring early summer time frame. Where irrigation cannot be provided, the use of erosion mats such as used in this study will play an even more important role in successful growth and establishment, especially for spring seeding. In this situation, where site conditions included partial protection (shading) of the fine fescues, their performance was significantly better than on the more extreme open portions of the site. Again, this reaffirms their successful adaptation to drier, partially shaded areas of landscape use. In an effort to keep annual broadleaf weed competition from becoming excessive, mowing at about three inches was utilized during the early establishment period. What is unknown is whether or not that played a role in the poor survival in the hot and dry

8 exposed areas of the plots. Hard fescue and sheep fescue have very good to excellent drought tolerance and would be expected to survive relatively harsh conditions. However, even mowing under relatively high mowing heights would have limited the extent of root development perhaps to the degree that it impacted the plant s ability to survive the two years of very dry conditions from late spring through mid-summer. Because mowing has the ability to negatively impact turfgrass rooting, it may have been better to minimize or even eliminate mowing on this site and used an herbicide to manage potentially excessive weed competition early during the establishment period. This would have allowed the development of a deeper, more robust turfgrass root system and perhaps provided better tolerance, even survival, to the environmental stresses posed on this site. In addition to the mowing, there were relatively high levels of Canadian geese feeding on the lower two-thirds of most plots during the late summer and fall periods of Again, that kept plant heights very short, well below the three inch mowing height, and hence would likely have had a negative impact on turfgrass rooting depth. In turn that could impact survival and recovery during and following the hot, dry periods. While all plots experienced at least some degree feeding, it did appear to be less on the two tall fescue plots. The seeded and sodded tall fescue plots performed remarkably well with respect to their ability to tolerate and recover from hot dry conditions. Also, there appeared to be little overwintering injury due to lack of hardiness; a problem previously limiting the use of tall fescues in this region. In addition, there did not appear to be any particular advantage of using tall fescue sod versus seeding tall fescue under a Futerra erosion control mat in this study. Most of their ratings on all characteristics were similar throughout the course of the study. Acknowledgements The University of Minnesota Extension would like to sincerely thank the extremely high level of cooperation and participation provided by the Hennepin County Department of Environmental Services in helping to carry out all of this project s components. We sincerely appreciate their time and effort in this project especially their willingness to create and install very high quality signage at the site explaining the project and labeling the various fine and tall fescue plant material as an aid for public viewing. See Picture 66. Respectfully submitted Bob Mugaas Extension Educator Horticulture University of Minnesota Extension