(26) NEW USES OF PGRS IN ORNAMENTALS: CONFIGURE (6-BA) INCREASES BRANCHING OF HERBACEOUS PERENNIALS

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1 (26) NEW USES OF PGRS IN ORNAMENTALS: CONFIGURE (6-BA) INCREASES BRANCHING OF HERBACEOUS PERENNIALS Joyce Latimer and John Freeborn 1 ABSTRACT Many herbaceous perennials are poorly branched, slow to fill out the pot, and produce few propagules. Configure (6-BA, Fine Americas, Inc.), labeled for branching of floricultural crops, was evaluated on a variety of perennials. Configure improved the basal branching of Echinacea purpurea Doubledecker with a three-fold increase in the number of new shoots per plant at two weeks after treatment. E. purpurea White Swan had a better branching habit and was more responsive to Configure. Additional crops tested with 600 ppm Configure were responsive as well. Configure treated Heuchera x Raspberry Ice had 60% more basal branches than untreated plants while treated Leucanthemum x Alaska showed only a short-term increase in basal branching. Untreated plants of Gaillardia arista Dazzler had 23 basal branches at four weeks after treatment and the plants treated with Configure had 153 branches. At eight weeks after treatment, these treated plants had nearly 60% more flowers than the untreated plants. Configure offers a new tool for improving the finished quality and propagation potential of a number of herbaceous perennials. INTRODUCTION Enhancement of plant branching improves plant architecture, tends to provide some growth regulation, improves pot fill and thereby may reduce crop time, may increase number of flowers and increases available propagules on stock plants. Plant growth regulators (PGRs) that enhance branching include ethephon (Florel), BA (benzyladenine, Configure), dikegulac sodium (Atrimmec or Augeo), cyclanalide (Tiburon) and methyl esters of fatty acids (Off-Shoot-O). These PGRs are frequently called chemical pinchers because they generally inhibit the growth of the terminal shoots or enhance the growth of lateral buds, thereby increasing the development of lateral branches. They can be used to replace mechanical pinching in many crops. Manual pinching can be used to improve the shape of the plant, increase branching, and control excessive stretch. However, the labor costs of pinching and the subsequent delay in plant development may not make it an economically feasible option of controlling growth of many crops. Furthermore, it may not result in an increase in branching. Pinching of Clematis suppressed leader lengths throughout the growing period, but there was no increase in the final number of laterals (Puglisi, 2002). Pinching Goldflame honeysuckle reduced growth through four weeks after treatment, but did not increase the final number of laterals (Brunner et al., 2001). 1 Department of Horticulture, 301 Saunders Hall, Virginia Tech, Blacksburg, VA

2 The goal in enhancing branching of floriculture crops is to activate dormant buds or stimulate the formation of adventitious buds by an application of PGRs. However, it is also critical that these new axillary buds develop and grow out to form normal branches. Configure (Fine Americas, Inc., Walnut Creek, CA) is a relatively new formulation of a synthetic cytokinin, 6-benzyladenine. It is an inexpensive PGR that enhances branching of a wide variety of floricultural crops. Configure stimulates, but does not cause, an increase in branching. Therefore, timing of the application is critical to a good branching response. Read the label for details of when to apply for optimum response. BA has a short period of activity and has no residual in the plant. So, multiple applications may be useful with many crops. Furthermore, it is not well translocated in the plant so thorough coverage is required. Screening trials with a wide variety of annuals and herbaceous perennials have identified a large number of crops with increased basal or lateral branching in response to Configure (Carey, 2008). Depending on the timing of the Configure application, BA increases branching of the phyllocades or, when applied during floral initiation, increases the number of flower buds breaking on Christmas cactus (Carey et al., 2009). Pansy and exacum are very sensitive to spray applications of Configure with long-lasting leaf yellowing even at low rates, 50 to 100 ppm (Carey et al., 2009). Phalaenopsis orchids treated with a foliar spray of 200 or 400 ppm Configure, applied two weeks after cold induction, increased the number of inflorescences per plant, enhanced the branching of the flower spikes and increased the flower count per spike resulting in 3 to 8 more flowers per plant than controls (Forney, 2008). Configure at 500 to 3000 ppm increased basal branching of Hosta (Keever, 1994). At lower rates, 300 to 600 ppm, Configure increased basal branching of Echinacea White Swan, Doubledecker, Magnus, and Ruby Star (Latimer and Freeborn, 2008). Configure improved branching of other Echinacea cultivars in work conducted at Michigan State University where branching of Sunrise and Harvest Moon was increased 50% and 120%, respectively, with a single application of 300 ppm Configure (Padhye and Whitman, 2008). Perennials Solutions Consulting found increased branching of Echinacea After Midnight, Fatal Attraction, and Pink Double Delight after treatment with a single application of 300 ppm or two applications of 150 ppm Configure (P. Pilon, personal communication, 2008). Our goal in the work discussed below was to evaluate Configure for effects on branching of a wide variety of herbaceaous perennial plants. MATERIALS AND METHODS Screening tests were conducted in 2008 and Unless otherwise noted all crops were started as size 72 plugs obtained from Aris Horticultural, Inc. (Leola, PA) and planted into quart pots (1.1 liter) filled with Fafard 3B medium (Conrad Fafard, Inc., Anderson, SC). All Echinacea along with Delphinium elatum 'Galahad,' Leucanthem x Alaska, and Hemerocallis 'Strutters Ball' were potted in trade gallon pots (3.4 liter) 89

3 filled with Fafard 52 medium. The new Echinacea selections, Fragrant Angel, Merlot and Tiki Torch were obtained from Terra Nova Nurseries, Inc. (Canby, OR) as size 30 plugs. All plants were irrigated as necessary with 200 ppm N using Peter s Each plant species or cultivar was set up as an individual experiment with plants arranged in a completely randomized design with six to ten single plant replications depending on the crop. After plant establishment and resumption of growth (about two weeks after planting), Configure (6-BA, Fine Americas, Inc., Walnut Creek, CA) was applied as foliar spray at 600 ppm using a hand-held CO 2 pressurized sprayer. Sprays were evenly applied over a given time period to apply the label recommended volume, two quarts per 100 sq.ft. Control plants were treated with clear water. Data collected included plant height (from rim of pot to top of plant in cm), number of shoots or basal branches and/or number of lateral branches. All plants were examined for evidence of phytotoxicity. Data were subjected to t-test for determination of treatment effect within each species tested. RESULTS AND DISCUSSION The Echinacea cultivars were very responsive to Configure with increased basal branching (Table 1). The older seed propagated cultivars, White Swan, Magnus, Doubledecker and Ruby Star were more responsive than the newer selections, Fragrant Angel and Merlot, or interspecific hybrid, Tiki Torch, which exhibit stronger apical dominance. Although these new selections showed a significant increase in branching, these new branches did not develop during the subsequent flowering period. Removing flowers during the first season is recommended by some growers. That practice may enhance the grow-out of these new basal branches. Table 1. Echinacea cultivars treated with a single foliar spray of 0 (Control) or 600 ppm Configure (6-BA, Fine Americas, Inc.) showed increased basal branching at four weeks after treatment. Number of basal branches Configure Cultivar Control (600 ppm) Magnus * White Swan * Doubledecker * Ruby Star * Tiki Torch * Merlot * Fragrant Angel * *Significantly different from Control, paired t-test, p<

4 Many of the other herbaceous perennials screened for a branching response to Configure were responsive at some point during the test (all data presented in Table 2). Coreopsis Zagreb was very responsive to Configure at two weeks after treatment. However, the difference from control plants was no longer significant at four weeks after treatment. With the short term effects of Configure on plant development, this crop may benefit from multiple applications. One advantage to early branching is the potential to finish the crop out earlier by filling the pot more quickly. However, we did not evaluate root growth in these studies which would also be an important determinant for early sales. Table 2. Herbaceous perennials treated with a single foliar spray of 0 (Control) or 600 ppm Configure (6-BA, Fine Americas, Inc.) showed increased basal or lateral branching at two to six weeks after treatment (WAT). Number of branches Configure Crop Control (600 ppm) WAT Coreopsis Zagreb * 2 Euphorbia 'Chameleon' * 6 Gaillardia 'Dazzler' * 4 Gaura Siskiyou Pink * 4 Heuchera x 'Raspberry Ice' * 4 Leucanthemum x 'Alaska' * 2 Lobelia cardinalis * 4 Lychnis 'Vesuvius' * 4 Penstemon Husker Red * 4 Veronica Icicle * 2 *Significantly different from Control, paired t-test, p<0.05. Euphorbia Camelon showed increased lateral branching but no increase is shoots per pot. Gaillardia Dazzler was extremely responsive to the 600 ppm Configure. Not only was the number of basal branches increased but there was a non-significant trend toward an increase in the number of flowers per plant at eight weeks after treatment (control 39 vs. Configure 62). Gaura Siskiyou Pink plants treated with Configure exhibited an increase in the number of shoots per pot at four weeks after treatment (Control 5 vs. Configure 7.3) as well as increased lateral branching of those shoots. These increases translated into significant increases in the number of flower stalks per plant (Control 25.3 vs. Configure 36) and the number of flowers per plant (Control 160 vs. Configure 221). 91

5 Heuchera x Raspberry Ice plants treated with Configure had increased basal branching. These plants required destructive harvests to accurately count the number of basal branches after the count at four weeks after treatment. These plants did not flower during the test period. Leucanthemum Alaska increased basal branching at two weeks after treatment with 600 ppm Configure but there was no difference from controls at subsequent measurement dates. Again, multiple applications may sustain the increased basal branching relative to the controls. These plants also required destructive harvest to count basal branches. However, a limited number of plants were retained to examine effects on flowering. With only three single-plant replications per treatment, there was a tendency toward an increase in the number of flowers on plants treated with Configure (Control 14.5 vs. Configure 26) at ten weeks after treatment. Configure increased basal branching of Lobelia cardinalis, especially early in the test (Control 3.8 vs. Configure 12.8, at two weeks after treatment). This response persisted through six weeks after treatment. Although Configure did not increase the number of shoots per pot for Lychnis 'Vesuvius,' it did increase the number of lateral branches on the existing shoots. Flower numbers were not noticeably increased by the treatment. Configure increased the basal branching of Penstemon Husker Red and reduced plant height at four weeks after treatment. Veronica Icicle also showed a short term response to 600 ppm Configure. At two weeks after treatment, there was a significant increase in the number of shoots per pot (Control 2.5 vs. Configure 3.6). In addition, the number of lateral branches on treated plants was more than double that of control plants at this first measurement. These responses were not different from controls at subsequent measurement. Again, multiple applications may improve the persistence of the increased number of branches. The remaining crops did not exhibit a significant branching response to the single application of 600 ppm Configure. Multiple applications or higher rates may result in significant responses with these crops: Asclepias tuberosa Aquilegia Winky Purple White Delphinium elatum 'Galahad' Helenium 'Coppelia' Hemerocallis Strutters Ball Phlox paniculata 'David' Stokesia laevis 'Silver Moon' In summary, Configure could be used as a general treatment for a wide variety of herbaceous perennials with a good potential to improve the crop habit and a low potential for crop injury or negative results. None of the crops tested here exhibited any 92

6 phytotoxicity as a result of the Configure foliar sprays. With the short term activity of Configure in plant development, evaluation of early treatments (in the plug tray) would be beneficial to crop production as would the use of multiple applications, perhaps at lower rates. LITERATURE CITED Brunner, L.L., G.J. Keever, R.A. Kessler, and C.H. Gilliam Growth regulation effects of Lonicera x heckrotti (Goldflame honeysuckle). Proc. SNA Research Conf. 45: Carey, Jr., D.J The effects of benzyladenine on ornamental crops. Master of Science, Department of Horticultural Science, North Carolina State University, Raleigh, NC. Carey, D., W. Buhler and B. Whipker Stimulating plant growth. Greenhouse Product News 19(5):20, 22, 24. Forney, K Boosting Orchid Profits with PGRs. GrowerTalks 72(7): Nov Keever, G.J BA-induced offset formation in hosta. J. Environ. Hort. 12: Latimer, J. and J. Freeborn Enhance branching of Echinacea with PGRs. Greenhouse Product News 18(4):24, Padhye, S. and C. Whitman Production tips for top performers: Echinacea 'Sunrise' & 'Harvest Moon.' Greenhouse Grower, Nov online Puglisi, S Use of plant growth regulators to enhance branching of Clematis spp. Master of Science, Department of Horticultural Science, Virginia Polytechnic Institute and State University, Blacksburg, VA. 93