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Extension > Yard and Garden News > Initiation of the Northern EarthKind™ Rose Trials

Initiation of the Northern EarthKind™ Rose Trials

David C. Zlesak, University of Minnesota Extension Educator

In the spring of 2007 the Northern EarthKind™ Rose Trials began. There are literally dozens of old and new roses touted as being superior low-maintenance landscape performers for our region, but many do not routinely live up to these claims. As we read the advertisements, it is hard for us as consumers to find landscape roses at the garden centers not being described as hardy and disease resistant. The goal of this effort is to identify the most consistently beautiful, low-care, pest tolerant roses for our region through putting them through multi-year, multi-site trials under a typical landscape environment.

In the spring of 2007 the Northern EarthKind™ Rose Trials began. There are literally dozens of old and new roses touted as being superior low-maintenance landscape performers for our region, but many do not routinely live up to these claims. As we read the advertisements, it is hard for us as consumers to find landscape roses at the garden centers not being described as hardy and disease resistant. The goal of this effort is to identify the most consistently beautiful, low-care, pest tolerant roses for our region through putting them through multi-year, multi-site trials under a typical landscape environment.

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Photo 1: Regionally-adapted rose cultivars that thrive without excessive care exist, such as these plants of ‘John Davis’ (left) and ‘John Cabot’ (right) in St. Paul. The goal of EarthKind™ is to scientifically identify and endorse the best of them. David Zlesak

When I started as an Extension Educator in 2006, I knew a little bit about the EarthKind™ program started at Texas A&M and their work with roses in the South. The EarthKind™ program combines both research and extension/education. I was impressed with their program and called to see if there was a way we could begin a branch of EarthKind™ following similar principles in the north. To my delight, they were just as excited about the possibility as I was. In January 2007 the EarthKind™ team invited me down for a day long EarthKind™ symposium in Houston. I joined a group of about 100 Master Gardeners, rosarians, and people just passionate about plants for this wonderful series of educational sessions devoted to all aspects of EarthKind™ (it includes multiple components to support environmental stewardship of the ornamental landscape) and toured some of the research sites. Conveying this experience with the University of Minnesota Extension Horticulture team, we knew this was something we wanted/needed to be a part of. They had a strong foundation and growing national recognition, and partnering with them in this important research instead of trying to start a completely independent effort would be the best use of limited resources. Before going into specific details about the Northern EarthKind™ Rose Trials and other exciting opportunities we have to expand into herbaceous perennial and shrub trials, I would love to share with you highlights of the history of EarthKind™ and a general overview of the program.

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Photo 2: The day long EarthKind™ Symposium hosted in Houston, Texas in January of 2007 introduced me to EarthKind™ team members and gave me a great overview of the program to convey to University of Minnesota colleagues. David Zlesak

Background of EarthKind™

In the early 1990’s scientists at Texas A&M University initiated EarthKind™, a program serving as an umbrella for research-based information regarding sound environmental stewardship of the ornamental landscape. At this time the need for tested information to help answer questions of people interested in more sustainable practices were growing and there was limited data on which to base recommendations. Dr. Steve George, the founder of EarthKind™, and a handful of colleagues began this huge task with their limited resources to begin to address these questions for those they served in the state of Texas. Rose cultivar trials, soil health and nutrition, and turf management were some of the areas they initially focused their attention on.

They recognized there was a need for this kind of information in context of regional environmental conditions beyond the citizens of Texas and the program expanded. The program has since expanded throughout the United States and some additional countries (Canada, Bermuda, India, and New Zealand). The mission is to provide all sectors of the horticulture industry (i.e. consumers, nurseries, landscapers, municipalities, retailers, etc.) with regionally appropriate, trustworthy, cutting-edge, research-based information regarding environmental stewardship of the ornamental landscape. With all the connotations, contention, and diversity in definitions surrounding recognizable terms like sustainable and organic, the new and straightforward term EarthKind™ was coined by Dr. Steve George. The goal is to use the most kind practices to the earth as possible as we identify plants and management systems that still preserves the general vision of what people deem as an acceptable landscape so it will be implemented and have impact. The EarthKind™ approach can be applied to all facets of the landscape: ornamentals, turf, vegetables, and fruit. Areas of emphasis that started the program and continue strongly include 1). identifying soil and nutrition management strategies which are low input, effective, and recycle nutrients from municipal yard waste thus reducing pressure on overcrowded landfills, 2). identifying regionally-adapted plant materials which perform well under local climatic conditions, and 3). increasingly methods and plant materials that help to conserve limited water resources.

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Photo 3: Dr. Steve George, the founder of EarthKind™, is passionate about this program and is a great team builder and leader. David Zlesak

Plants in cultivar trials are trialed using low maintenance principles and the knowledge gained from what has been learned through nutrition management studies (compost added initially and organic mulch maintained at a 3” layer), water saving practicies (watering during the establishment phase and then only in cases of extreme drought afterwards), no fertilizers (beyond the initial compost and maintained mulch layer), no deadheading or pruning, and no pesticides. In addition, it was confirmed early on that own-root roses (propagated from cuttings and not grafted) tend to be longer lived and more adaptable. Therefore, all EarthKind™ rose trials use only own-root roses and for winning EarthKind™ rose cultivars to be EarthKind™ they need to be sold as own-root plants as well.

Roses have become the model landscape shrub for EarthKind™ cultivar evaluation for some very good reasons. Roses are our national flower and have long been a favorite for many gardeners and landscapers due to their extended season of flowering, diversity of flower color, fragrance, form, plant size, and growth habits. In addition, with the great diversity among them in performance, cultivar trials are very useful to highlight the best performing roses for a typical landscape. By using the EarthKind™ approach, regionally adapted cultivars can be identified that demonstrate consistently superior performance well-suited to particular climates. Roses that are EarthKind™ for one region may or may not prove adapted enough to be EarthKind™ in another region. EarthKind™ winning cultivars can be endorsed with confidence to the general public, landscapers, nurseries, and municipalities. With some basic attention given to soil preparation, site selection, mulch, and irrigation during establishment, these roses are highly likely to succeed. This results in many positive benefits including:

  • Greater satisfaction and people more likely to continue gardening.
  • A greater positive impact on the environmental with less need of pesticides and over application of fertilizers to try to make poorly adapted plants succeed.
  • Greater financial savings for especially municipalities and others managing large landscapes due to more efficient use of limited financial and human resources.
  • An open door to provide those interested with more information about other components of EarthKind™ to support environmentally sound landscape stewardship.
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Photo 4: There is great variation among rose cultivars for pest susceptibility and landscape performance as seen among these roses at the Minnesota Landscape Arboretum. David Zlesak

Status of EarthKind™ rose research before the Northern EarthKind™ Rose trials began

Scientists at Texas A&M University identified 17 rose cultivars that have earned EarthKind™ status for the South (two more have been added since for a total of 19). For a rose to become EarthKind™ it must: Perform well in an initial large, university trial making the first cut and then perform consistently well regionally across multiple sites hosted by Master Gardeners, parks, botanical gardens, interested individuals, and/or community gardens. The roses that are included in the large phase one university trials are very carefully chosen taking into account any previous trial data from within and outside the region and recommendations from horticultural leaders including nursery professionals and rose societies. The goal is to use the limited resources available for these trials very wisely. By clearly eliminating roses that do not possess the level of pest tolerance or general adaptability necessary to merit EarthKind™ from the start, there will be more resources to devote to those that are more likely to prove themselves as EarthKind™. Although antidotal evidence helps to focus in on roses to initially include in the trials, to earn the prestigious EarthKind™ status, roses need to have supporting data behind them from the full EarthKind™ trial protocol confidently supporting their inclusion among this very elite group of cultivars.

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Photo 5: Many of the gorgeous EarthKind™ winning roses for the South, like ‘Mme. Antoine Mari’, are not hardy enough to reliably survive winters in our northern climate. David Zlesak

For the larger, initial university trial where a hundred or more cultivars are trialed, the duration of the trials is four years. Data is taken monthly during the second through fourth growing seasons with no data taken during year one to allow for plant establishment and any residual pesticides to dissipate. The monthly data is taken on traits assessing pest tolerance, flowering characteristics, and overall plant habit and landscape impact. The very best of these roses in the phase one university trial, along with a reference or standard cultivar for comparison, are then planted at several additional sites across the region. These roses are monitored for three years with data taken years two and three. After this point there is enough data to understand the cultivar’s performance throughout the region and designate winners with confidence. Those roses that are on the fence may be put in additional secondary trials until enough data on their overall performance is gathered to confidently decide if they have earned EarthKind™ recognition or not. Although this extended timeframe slows down the evaluation process in comparison to typical rose evaluation programs that typically grow roses only two years, it elevates the value of roses earning EarthKind™ designation. With variable climatic conditions over years, the extended trial period also helps to expose the plants to more environmental factors and allow them to mature and assess their long term landscape adaptability. The priority isn’t to have newly designated cultivars each season to fuel marketing efforts, but to have those that are designated as EarthKind™ to truly possess superior performance in a typical landscape in the region of designation.

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Photo 6: ‘BUCbi’ (Carefree Beauty™) serves as the check or reference cultivar in EarthKind™ trials. It has proven to be EarthKind™ in the South and is reliably crown hardy here at the Minnesota Landscape Arboretum. David Zlesak

Besides the previously mentioned components of EarthKind™ trialing (number of years under evaluation; nutrition, water, and pest management components; regional adaptation; and monthly data collection that is generally a higher frequency of data collection during the growing season than other rose evaluation programs), the EarthKind™ rose program has a number of other features that set it apart from the leading rose evaluation programs. This includes attention to blocking, check or reference cultivars, and more of an independent consumer-based perspective and driving force. Although EarthKind™ works with nurseries to learn about new roses and obtain plants, nurseries are not a primary funding source for the work and all rose cultivars, no matter who bred them or when they were bred, can be included if they have the characteristics that suggest they have the potential to earn EarthKind™ status.

Blocking and check or reference cultivars are critical elements to cultivar trials of most crops and are employed in EarthKind™ trialing. Blocking (we use a randomized complete block design) involves separating out the replicates of a particular cultivar across the trial site. They are separated in different complete subsections of the garden with representatives of all the cultivars randomized when planted for more statistical power when analyzing the data. When, for instance, all four plants of a particular cultivar are planted by each other in a trial, like done in many of the leading rose trials, one does not know for sure to what extent the rose’s performance (good or bad) can be attributed to the cultivar itself or if the particular region of the garden they are all planted in is more or less suitable than another location. For instance, when all four plants of a cultivar with generally above average disease tolerance are planted next to a very susceptible cultivar, the true resistance of the above average cultivar may be difficult to see with all of the innoculum being spilled onto it from its neighbor. If blocking with randomization was used, the cultivar with above average resistance would be planted across the garden next to various other roses and the variation in disease incidence on the cultivar can be better documented and overall it should be possible to determine it has above average disease resistance. Having a reference or check cultivar common throughout all the trials is also important. The performance of this cultivar relative to the others can provide useful information for comparisons, especially when all trial cultivars for secondary EarthKind™ trials cannot be accommodated in a single garden.

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Photo 7: The EarthKind™ Brigade includes several of the roses bred by the late Dr. Griffith Buck from Iowa State University such as ‘Winter Sunset’. Ron Shaw

Besides the continuing EarthKind™ rose trials going on in the South through the support of many partners including significant support from the Houston Rose Society, there is a collection of 30 rose cultivars, known as the EarthKind™ Brigade, that are being evaluated across the mid section of the United States. These 30 roses have enough cold tolerance to survive the winters in a large part of the nation, but most of these cultivars are not reliably winter hardy in USDA cold hardiness zones 3 and 4. There is a need to identify EarthKind™ worthy roses for zones 3 and 4 and the initiation of the Northern EarthKind™ Rose Trials.

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Photo 8: The first Northern EarthKind™ Rose Trial was planted at UMore Park in Rosemount, Minnesota. Compost was incorporated within the four blocks and one of each of the 20 cultivars were planted in each block. David Zlesak

Initiation of the Northern EarthKind™ Rose Trials

Fortunately, there are disease-tolerant roses which will reliably survive our zones 3 and 4 winters without protection. Information gathered on the performance of such roses from nursery professionals, rose societies, and observations in our regional landscapes and public rose gardens formed the foundation with which we developed this first collection of 20 rose cultivars to trial. At this time, part of the criteria for cultivar consideration is that cultivars need to rebloom during the growing season and also rugosa roses are not being evaluated due to their susceptibility to iron chlorosis in higher pH soils. These criteria may be changed for future trials.

In addition, there is a modification to the pruning criteria and evaluation model compared to the South. Since most landscape roses encounter dieback in our climate, pruning will be allowed to remove winterkilled tissue in the spring. In addition, due to the growing reputation of EarthKind™ and wanting to provide information for northern gardeners, the trial will start with multiple sites across the north initially. This is also possible as there is a relatively small number of cultivars that have reputations of being reliably cold hardy and pest resistant for the north to begin with.

As of now there are 8 complete Northern EarthKind™ trial sites and one Northern EarthKind™ demonstration site at Muriel Sahlin Arboretum in Central Park in Roseville (a demonstration garden has one each of the cultivars planted with signage to promote the program and provide conformational data as to the performance of the different cultivars in the full sites). Three of these trial sites are in Minnesota (University of Minnesota Outreach, Research, and Education Park in Rosemount, zone 4; Centennial Park in Moorehead, zone 3; and The Sisters of St. Benedict in Crookston; zone 3), one in Iowa (The Horticulture Research Farm outside of Ames, border of zones 4 and 5), one in Nebraska (Haworth Park in Bellevue, border of zones 4 and 5), and Colorado (outside of Fort Collins, zone 3). The additional two are located in Kansas (John C. Pair Horticultural Center, Haysville, KS) and Texas (Texas A&M Commerce, Commerce, TX) to see how far south these roses perform well for possible inclusion in future EarthKind™ trials in those regions. Key collaborators for this effort and hosts of these sites include: Dr. Steve George, Dr. Derald Harp, Dr. Jason Griffin, Kathleen Cue, Anita and Mike Eckley, Joanne and Bob Langabee, Tamla Blunt, Randy Nelson, Nick Howell, Eric Castle, Mike Klawitter, and Patti Sullivan.

The twenty rose cultivars included in the current Northern EarthKind™ Rose Trials.

Cultivara

Horticultural class

Flower color

Approx. height in feet

Radbrite (Brite Eyes)

Large flowered climber

Pink Blend

6

RADramblin (Ramblin' Red)

Large flowered climber

Red

8

John Cabot

Hybrid kordesii

Deep magenta

10

John Davis

Hybrid kordesii

Light Pink

6

Quadra

Hybrid kordesii

Red

6

William Baffin

Hybrid kordesii

Pink

10

Alexander Mackenzie

Shrub

Light Red

6

BAIine (Yellow Submarine)

Shrub

Yellow

3

BAIlena (Lena)

Shrub

Light Pink

2.5

BAIole (Ole)

Shrub

Blush white

2.5

BAIore (Polar Joy)

Shrub

Pink

5

BAIset (Sunrise Sunset)

Shrub

Pink Blend

3

BAIsven (Sven)

Shrub

Purple

3

Bucbi (Carefree Beauty)

Shrub

Pink

4

Frontenac

Shrub

Pink

3

George Vancouver

Shrub

Light Red

5

Morden Blush

Shrub

Blush white

4

Prairie Joy

Shrub

Light pink

4

Seafoam

Shrub

White

2.5

Summer Wind

Shrub

Orange-pink

4

a Trademark or exhibition name, if different from cultivar name, is listed in parenthesis.

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Photo 9: The Northern EarthKind™ Trial planted outside of Ames, Iowa at the Horticulture Research Farm. David Zlesak

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Photo 10: Some of the Northern EarthKind™ Rose Trial cultivars under evaluation include: A). ‘Frontenac’, B). ‘George Vancouver’, C). ‘BAIole’ (Ole), and D). ‘BAIset’ (Sunrise Sunset™). David Zlesak

Planting occurred in spring of 2007 for the UMore Park site and late 2007 or 2008 for the other sites. The first year of data was collected at UMore Park in 2008 and will begin at the other sites in 2009. By the end of 2011, the data for all of these sites should be complete with the first possible Northern EarthKind™ winners announced in 2012. All the sites, excect for the Colorado site, are located within public gardens or research facilities. All of the Minnesota sites are easily accessible to the public for viewing.

Complementary EarthKind™ Work and New EarthKind™ Trials on the Horizon

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Photo 11: Several hundred individual boxes of rose leaves were needed to evaluate the dozens of cultivars for their susceptibility to the three races of the pathogen causing black spot. Jolyne Pomeroy, Brandi Miatke, Vance Whitaker, and David Zlesak are pictured after finishing a round of inoculations in the laboratory. David Zlesak

In addition to working with collaborators to initiate the Northern EarthKind™ Rose Trials, the University of Minnesota is serving a key role for the EarthKind™ team in surveying roses for their tolerance to multiple races of the fungus (Diplocarpon rosae) that causes black spot, a very problematic disease in roses. The roses currently being characterized are the ones that have won EarthKind™ in the South, the 30 roses in the EarthKind™ Brigade, the 20 in the Northern EarthKind™ Rose Trials, and some recent promising cultivars touted as having extreme blackspot resistance. Vance Whitaker studied isolates of the fungus for his Masters from collections made all over Eastern North America for his Masters with his advisor Dr. Stan Hokanson. These isolates fell into three different races or forms. These races are well preserved and available to use to challenge these roses to ascertain their resistance under laboratory conditions. These results will be compared to field resistance ratings for the predictability of this lab assay in characterizing the performance of these cultivars in the landscape. If it proves to be predictive, this relatively quick assay can prove to be very useful in objectively helping narrow down which cultivars merit inclusion in future trials. We may be able to determine a minimum threshold of resistance a cultivar needs to have in these assays to include in the trials and be able to hold up in the landscape to this very destructive disease and have the potential to earn EarthKind™. With the variability in this pathogen, being able to assess resistance to the different forms out there is a tremendous advantage. Variable reports for resistance of a cultivar often stem from which form(s) of blackspot happen to be present in a particular garden.

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Photo 12: These leaves are of the same rose cultivar. This rose is highly resistant to one of the races (A.), but very susceptible to another (B.). This highlights the variability of performance possible across different gardens depending on which form of the pathogen is present. David Zlesak

The next set of Northern EarthKind™ trials are on the horizon. In order to best get an idea of the performance of some of the newer landscape roses in our climate under lower input conditions, over 20 such cultivars have been planted in preliminary trials at UMore Park, Lyndale Park Rose Garden (Minneapolis), Virginia Clemons Rose Garden (St. Cloud), and the Leif Erikson Rose Garden (Duluth). Observations on their general disease tolerance and winter hardiness will be very helpful in determining which merit inclusion in the next Northern EarthKind™ Rose Trial. In the near future there are plans to initiate regional EarthKind™ herbaceous perennial trials and shrub trials. Members of the EarthKind™ team met this past October to brainstorm how to get this work off the ground. Dr. Ann Marie Vanderzanten from Iowa State University will lead the national effort for EarthKind™ Perennials and our own Kathy Zuzek, University of Minnesota Extension Educator, will lead the national effort for EarthKind™ Shrubs.

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Photo 13: Five plants each of 21 recent or new landscape roses were planted at UMore Park in spring of 2008 in order to learn of their pest tolerance and winter hardiness for possible inclusion in the next Northern EarthKind™ Trial. David Zlesak

Efforts are also underway to continue to expand EarthKind™ internationally (EarthKind™ work is currently underway in the United States, Canada, Bermuda, India, and New Zealand) and to initiate more work in turf and soil management. Part of the goal of international EarthKind™ rose research is to help people identify the most adapted roses for their regions and then eventually share and trial such roses across regions to see how widespread these roses are adapted. This will lead to a growing collection of the world’s most adapted landscape roses that will not only serve those that want to grow adapted roses in their region, but also breeders as they can use this information to narrow in on parents that will hopefully transmit superior characteristics to new roses. More information about EarthKind™ resources can be found at: http://earthkind.tamu.edu/ and http://earthkindroses.tamu.edu/ . In addition, a review article documenting the EarthKind™ rose research has been accepted and will be coming out in a special issue of the scientific journal Floriculture and Ornamental Biotechnology devoted to rose research slated for release in February 2009. (http://www.globalsciencebooks.info/Journals/FOB.html) Please look for periodic updates about EarthKind™ research in the Yard and Garden News and other publications.

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