HORTSCIENCE 49(4):509–512. 2014. popular because that is a difficult color to find in other flowering bedding , especially ones adapted to flowering continually in re- L. ‘John Eustice’: A New gions with long warm summers. In the past decade, elite genotypes of Vigorous Lavender–blue Flowered primarily compact growing A. houstonianum have been introduced as vegetatively propa- Summer Annual gated and are included in popular branded lines. Examples include the David C. Zlesak1, John A. Eustice, and Cody L. Gensen ArtistÒ (Proven WinnersÒ) and PatinaTM University of Wisconsin–River Falls, 410 S. 3rd Street, River Falls, WI 54022 (SyngentaÒ) series of ageratum, which are widely available in independent garden cen- Additional index words. , bedding plant, cut flower, floss flower, interspecific ters and box stores as bedding plants in the hybrid United States in spring. Typically sold in 10-cm pots or in mixed patio containers, vegetatively propagated ageratum cultivars The genus Ageratum is comprised of 29 nuclear controlled male sterility provide are typically grown to a relatively large size species in the Asteraceae that are native to the breeders with effective tools to facilitate and tend to be more expensive than the seed Americas (Johnson, 1971). Ageratum hous- controlled crosses (Stephens, 2006) and are grown cultivars typically sold as smaller tonianum (commonly called ageratum or particularly useful because individual florets plants in packs. However, exceptional per- floss flower) is the predominant commer- are very small and tedious to emasculate. formance for traits like heat tolerance, strong cially grown species and is marketed and Ageratum houstonianum and its relatives continual bloom, or very symmetric plant sold primarily as a spring bedding plant and produce terminal inflorescences with capitula habit in many vegetatively propagated ager- to a lesser degree as a cut flower (Stephens, containing only disk florets and are typically atum genotypes provides added value and 2006). Floss flower can be a short-lived peren- arranged in a compound cyme. Disk florets in helps justify the extra expense. nial in frost-free areas (USDA cold hardiness a single capitulum open in concentric rings zones 9 and warmer) and in practice is grown from the perimeter to the center over 1 Origin as a summer annual. Ageratum does well in week. The corolla of an individual floret is part to full sun and in a range of soil types funnelform with typically a white base and An ageratum breeding program was initi- with moderate fertility and moisture. Most colored tip. The corolla ends in five deltoid ated in 2002 by John Eustice and David bedding plant cultivars have a compact plant lobes and the adaxial and abaxial sides are Zlesak in St. Paul, MN, which led to the habit (typically growing 10 to 25 cm tall) typically similar in color. However, in some development of ‘John Eustice’. Several seed- with capitulums held close to the foliage. Cut genotypes, lobe color can be markedly dif- propagated A. houstonianum cultivars were flower cultivars have been selected for taller- ferent on either side leading to a bicolored acquired (e.g., members of the Hawaii series growing plants (typically growing 40 to 60 cm effect to the capitulum between open and and ‘Blue Danube’ and ‘Blue Mink’) as well tall) with strong stems and longer internodes unopened florets. The style is prominent and as wild-collected germplasm as parental ma- that more prominently elevate and display the forked and typically the same color as the terial. The wild species genotypes used as inflorescences. adaxial side of the corolla lobes. Plants pro- parents were obtained from multiple sources Ageratum houstonianum is native to duce oppositely arranged ovate, deltoid, or including a potted plant of A. littorale A. Mexico and Central America and has escaped slightly cordate leaves on vegetative growth Gray purchased from a Florida native plant cultivation and naturalized in multiple warm andtransitiontoalternatearrangementasthe nursery and multiple seed accessions that regions of the world (Johnson, 1971; Stephens, stem produces reproductive tissue. were not A. houstonianum. The identity of 2006). Wild collections and most cultivars are Ageratum houstonianum is generally easy these wild species obtained as seed could not diploid (2n =2x = 20), whereas some culti- to grow, floriferous, and it does not typically be confidently determined by the authors. vars are polyploid (Johnson, 1971; SakataÒ have significant pest issues, all of which Interspecific hybrids were generated between Ornamentals, 2013; Stephens, 2006). Sporo- contribute to its popularity. Currey et al. the A. houstonianum cultivars and the various phytic self-incompatibility is present in this (2011) list several annual bedding plant lavender–blue flowered, generally tall-growing species and is the result of a single locus with species categorizing them for floral induc- Ageratum spp. a linear dominance series of alleles (Stephens tion, and the ageratum cultivars surveyed were The primary objective of the breeding et al., 1982). Self-incompatibility and also all facultative long-day plants and supplemen- program leading to the development of ‘John tal irradiance did not impact induction. Sched- Eustice’ was to combine the very strong uling ageratum to produce flowering and butterfly attraction, glossy foliage, vigorous salable plants is therefore straightforward growth, and loose branching habit that ele- Received for publication 3 Jan. 2014. Accepted for and relatively easy for growers. Periodic vates and separates the capitula found in publication 7 Feb. 2014. challenges that can be encountered when some of the wild species parents with the We thank Mike and Rachel Gooder, Stacy Bryant, producing ageratum include root rot dis- wide range of flower color, early flowering, and the rest of the team at Plantpeddler for being eases in overly saturated soils and infesta- larger capitulum size, and attractive plant great partners throughout the commercialization of ‘John Eustice’ and the other ageratum genotypes in tions of thrips and whiteflies in the greenhouse. habit of commercial A. houstonianum.Su- the Monarch GrandeTM and Monarch MedianoTM Outdoors in amenable soil with adequate light, perior F1 and subsequent advanced genera- series. We also thank Gail Soens for her help caring water, and drainage, ageratum is typically tion genotypes were selected, vegetatively for ageratum plants and providing garden space. a very dependable ornamental. Ageratum is propagated through herbaceous stem cut- ‘John Eustice’ is named in honor of the late John also quite resistant to herbivory including tings to preserve them, and used as parents Eustice, who initiated the ageratum breeding pro- Japanese beetles, a problematic insect in the in successive generations. During the first gram with David Zlesak that led to this special eastern United States that feeds veraciously few years of the breeding program, pedigree . John was a talented horticulturist that has on a wide host range of landscape plants breeding was used. Crosses were strategi- made many valuable contributions to horticulture (U.S. Department of Agriculture, 2004). Ag- cally made to obtain progeny possessing including his written publications on a range of horticultural topics, passion for learning about and eratum cultivars are available in a range of combinations of unique and desirable traits. sharing plant materials, and knack for artistic, yet flower colors including lavender–blue, lav- This included recovering recessive flower practical landscape design. He is deeply missed. ender, pink, white, purple, and mauve, but the colors to have the full range possible in 1To whom reprint requests should be addressed; most popular color of ageratum is lavender– ageratum, obtaining well-branched plants e-mail [email protected]. blue. Lavender–blue cultivars are particularly with desirable growth habits, selecting plants

HORTSCIENCE VOL. 49(4) APRIL 2014 509 with smoother leaves and stems, and priori- tizing early and continued flowering. As the breeding program progressed and led to a collection of genotypes with a com- bination of desired phenotypes, the primary breeding method shifted from pedigree breed- ing to primarily recurrent mass selection. Seed was saved and bulked from clonally propa- gated interspecific advanced selections grown adjacent to each other in outdoor garden beds. The original parents and interspecific hybrids in this breeding program are highly self- incompatible. Viable seeds do not form when plants are isolated indoors without vectors for cross-pollination, but viable seed does form when multiple genotypes are grown near each other outdoors and butterflies and other polli- Fig. 1. ‘John Eustice’ ageratum 14 Sept. 2013 in an outdoor garden bed in Roseville, MN, from a 5 July 2013 planting date displaying abundant and well-spaced capitula. nators are present. By shifting away from a traditional pedigree breeding method, it has become unfeasible to know the exact pedi- grees of seedlings in advanced generations. young plants. The additional comparison using representative half open capitula of Using recurrent mass selection, seedlings were cultivars (Blue Horizon, Field’s Blue, Hawaii each cultivar and the color charts from the raised from open-pollinated seed bulked from Blue, and Tycoon Blue) are commercially Royal Horticultural Society (2001) (Table 2). multiple female parents that shared similar, propagated by seed. To standardize the trial, Ploidy was determined for each cultivar desirable traits (i.e., glossier foliage, clear and cuttings were taken and rooted of seed- through direct chromosome counts of root attractive flower colors, early flowering, etc.). propagated cultivars so everything going tip cells at metaphase using the procedure ‘John Eustice’ germinated in April of into the comparative trial was propagated outlined in Zlesak et al. (2005). 2010 from seed collected and bulked from using the same method. Going into the trial, ‘John Eustice’ and ‘Blue Horizon’ were unreleased interspecific lavender–blue flow- plants were 4 weeks old or older. Before significantly larger-growing than the other ered selections during the summer of 2009. planting, all plants were cut back to 5 cm. ageratum cultivars and had inflorescences The population leading to ‘John Eustice’ Planting occurred on 5 July 2013 in Rose- displayed significantly higher above their was germinated and transplanted into packs ville, MN, using a randomized complete block foliage (Table 1). Comparing the two largest indoors and then transplanted into outdoor design with three blocks and one replication of growing cultivars, ‘John Eustice’ had more garden beds in late spring in Woodbury, a row of four adjacent plants of a cultivar per inflorescences per plant than ‘Blue Horizon’ MN. During the summer of 2010, ‘John block. Plants were planted 25.4 cm apart both and leaf blades that were smaller, both valu- Eustice’ was identified as a superior geno- between and within rows. The soil was a able traits for use of ‘John Eustice’ as a cut type with exceptional floral traits and plant sandy loam. The bed was mulched with 5to flower cultivar. ‘John Eustice’ had signifi- habit. It was first vegetatively propagated in 7 cm of hardwood chips, irrigated as needed cantly more capitula per inflorescence than Sept. 2010 by herbaceous stem cuttings. (plants received at least 2.54 cm of water per all the other cultivars. When estimating the Over subsequent clonal generations and con- week from either rainfall or irrigation), and overall number of capitula per plant (multi- tinued trialing in both containers and ground fertilized at the recommended rate with a plying the mean inflorescence number and beds, the valuable characteristics of this ge- granular quick-release fertilizer (10N–4.4P– number of capitula per inflorescence), ‘John notype proved to be stable. 8.3K; IdealTM All-purpose Fertilizer; Eau Eustice’ had the most followed by ‘Agsantis’ Claire Cooperative, Eau Claire, WI). and then ‘Agpatblu’. The plant habit of ‘John Description and Performance Data from the cultivar comparison were Eustice’ was more similar to the cushion collected 14 and 15 Sept. 2013. Data were habit of the compact cultivars, which had ‘John Eustice’ is unique from other veg- taken on the two most developed plants per capitula displayed over most of the surface etatively propagated ageratum cultivars be- replication (each replication consisted of of the hemispherical plants (Figs. 1 and 2). cause of a combination of multiple valuable a row of four plants). The data were averaged ‘Blue Horizon’ had blooms displayed pri- traits. They include: a vigorous, mounded, over the two plants per replication to get marily at the top of the plant (Fig. 2). and slightly spreading plant habit; relatively a single value per trait per replication for The color varied between unopened and larger plant size than most bedding plant descriptive statistics, analyses of variance, opened florets for these cultivars all marketed ageratum cultivars; well-branched plant habit and mean separation (Duncan’s multiple as having blue flower color (Table 2). ‘Blue with strong stems that resist lodging; lavender– range test; P # 0.05). Data collected on an Horizon’ maintained the most consistent blue capitulums held prominently above the overall plant basis were plant height, plant lavender–blue color from unopened to opened foliage; relatively glossier foliage than typi- width (widest diameter was recorded along florets. Most of the rest of the cultivars cal ageratum cultivars; strong butterfly ap- with the diameter perpendicular to it and the possessed a relatively similar lavender– peal; early and continued flowering throughout two values were averaged), and number of blue color between unopened and opened the growing season; and a colorful and long- stems ending in inflorescences with at least florets, including ‘John Eustice’ (Fig. 3). lasting cut flower (Fig. 1). When used as a cut one capitulum containing an open floret. ‘Agpatblu’ and ‘Agsantis’ displayed the flower, blooms have remained attractive for Representative samples of three measure- greatest color differences between unopened 7 to 10 d, a typical and consistent duration the ments per plant were taken for: the number and opened florets with opened florets being authors found for ageratum generally. of capitula per inflorescence, diameter of lavender–blue and unopened florets being During the summer of 2013, a field trial capitula possessing open florets, length from lavender–pink. was conducted to compare the growth and the top of the inflorescence to the first node Chromosome counts revealed that ‘John flowering characteristics of six commonly with opposite leaf arrangement, leaf blade Eustice’ and all but one of the other cultivars available lavender–blue A. houstonianum length and width, petiole length, and inter- were diploid (2n =2x = 20). ‘Blue Horizon’ cultivars with ‘John Eustice’ (Table 1). node length between the first two adjacent was triploid (2n =3x = 30), which is ‘Agpatblue’ (PatinaTM Blue) and ‘Agsantis’ nodes with opposite leaf arrangement below consistent with its marketing (SakataÒ Orna- (ArtistÒ Blue) are vegetatively propagated, the inflorescence (Table 1). Color data were mentals, 2013). Polyploids compared with patented cultivars and were purchased as recorded for unopened and opened florets their diploid counterparts often display

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