tion of possible sources of inoculum (wild and other cultivated Stamps, R. H. 1992. Commercial leatherleaf fern culture in the United States ferns) is essential for avoiding the introduction of the disease of America, pp. 243-249. In Fern Horticulture: Past present and future perspectives. The proceedings of the International Symposium on the (Norman and Strandberg, 1997; Stamps et al., 1997; Strandberg Cultivation and Propagation of Pteridophytes, London England. Inter et al., 1997). The demonstrated susceptibility of a wide range of cept, Ltd., Andover, UK. ornamental fern species points out additional disease hazards Stamps, R. H. 1995. Irrigation and nutrient management practices for com for the production of these and other ornamental and land mercial leatherleaf fern production in Florida. Univ. of Fla. Coop. Ext. scape ferns which might be susceptible to fern anthracnose. Serv. Bui. 300. Stamps, R. H., J. O. Strandberg and D. J. Norman. 1997. Incidence, severity, and control anthracnose of leatherleaf fern. Proc. Fla. State Hort. Soc. Literature Cited 110:115-118. Strandberg, J. O., R. H. Stamps and D. J. Norman. 1997. Fern anthracnose; A Leahy, R., Schubert, T., J. Strandberg, R. Stamps and D. Norman. 1995. An guide for effective disease management. Univ. of Fla. Agr. Expt. Sta. thracnose of leatherleaf fern. Fla. Div. of Industry, Plant Pathol. Tech. Bui. No. 900. Gainesville, FL. Circ. No. 372. U.S. Dept. of Agr., Fla. Agr. Stat. Serv. 1998. Foliage, floriculture and cut Norman, D. J. andj. O. Strandberg. 1997. Survival of Colletotrichum acutatum greens. Report for May, 1998. Orlando, FL. in soil and plant debris of leatherleaf fern {Rhumora adiantiformis). Plant Dis. 81:1177-1180.

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EFFECT OF GROWTH REGULATORS ON FOUR POTTED ASIFLORUM LILY CULTIVARS

GaryJ. Wilfret of growth regulators for height control (Ball and Miller, University of Florida, IFAS 1996). Three chemical growth regulators are effective on Eas Gulf Coast Research and Education Center ter lilies and hybrid lilies (Davis et al., 1988) and have been Bradenton, FL 34203 evaluated as a soil drench, a foliar spray, or a bulb dip (Wil fret, 1987). Ancymidol (A-Rest®; ~-cyclopropyl-oc-(p-methyx- Additional index words. Ancymidol, , unicona- yphenyl)-5-pyrimidine-methanol) is the most commonly used zole, ornamentals, flowering, growth retardant, plant height. growth regulator on Easter lilies and is effective as a soil drench of 0.25 to 0.75 mg ai/pot (Giafagne and Wulster, Abstract Four Asiflorum lily cultivars were grown as potted 1986; Johnson, 1973; Larson andKimmons, 1971; Wilfret, and treated with growth regulators to retard plant 1987). Paclobutrazol (Bonzi®; (2RS, 3RS)-l-(4-chlorophe- height. Chemicals were applied as a soil drench with concen nyl)-4,4-dimethyl-2-(l,2,4-triazol-l-yl)-pentane-3-ol) has been trationsof ancymidol at 0, 0.25, 0.38, or 0.5 mg ai/pot, pa inconsistent in height control of lilies (Giafagne and Wulster, clobutrazol at 0,2, 3, 4, or 5 mg ai/pot, and uniconazole at 0, 1986; Wilfret, 1996), but 2 to 4 mg ai/pot applied as a soil 0.06, 0.08, 0.10, 0.12, or 0.14 mg ai/pot. Control plants (water drench has been effective in Florida (Wilfret, 1987). An ana drench) of 'Clubhouse', 'Modern Style', 'Best Seller', and 'Ro log of paclobutrazol, uniconazole (Sumagic®, (E)-(p-chlo- deo' flowered 46, 54,60, and 66 days after planting and were rophenyl)-4, 4-dimethyl-2-( 1,2,4-triazole-l-yl)-l-pentane-3-ol) 60.6, 82.5, 70.6, and 62.2 cm tall at flowering, respectively. has shown greater activity for inhibition of gibberellic acid Growth regulators had no effect on flowering time, number of , or size. Paclobutrazol at concentrations of 3 to synthesis (Davis etal., 1988). Soil drenches of uniconazole as 4 mg ai/pot produced plants 40 to 50 cm tall while uniconazole, low as 0.06 mg ai/potapplied to Easter lilies (Bailey and Mill even at the highest rates, yielded plants taller than an ideal er, 1989; Wilfret, 1996) or 0.1 mg ai/pot on hybrid lilies (Jiao marketable size. et al., 1990) significantly retarded plant height. Preplant bulb dips of Easter lilies (Wilfret, 1990) and hybrid lilies (Dicks et Asiflorum lily hybrids, derived from crosses between Eas al., 1974; Simmons and Cummings, 1977) in growth regula ter lily (Lilium longiflorum Thunb.) and Asiatic lily hybrids, tors produced shorter plants but plants were highly variable which developed through interspecific hybridization among in height. Preplant bulb dips of Asiflorum bulbs in ancymi as many as 12 lily species (Beattie and White, 1993), offer a dol, paclobutrazol, or uniconazole significantly retarded stem new potted plant for Florida growers. The Asiflorum cultivars, elongation (Ball and Miller, 1996). Optimum height control initially designated as L.A. hybrid by European plant breed was achieved with a 5 minute dip in uniconazole solutions of ers, have only been available for commercial production with 5 to 10 ppm. Some cultivars required a subsequent foliar in the last five years and can be used to complement potted spray of uniconazole to prevent late stem elongation (Anon., Easter lilies and hybrid lily production (Funnell and Heins, 1998). The purpose of this research was to evaluate the effect 1998). Asiflorum cultivars range in flower color from white of three growth regulators when applied as a media drench ('Royal Respect') to a plum red ('Cinnabar') and several have on height of four Asiflorum lily cultivars. a sweet freesia-like scent. Asiflorum lilies were developed for use as cut flowers, with stems 70 to 130 cm tall, but their po Materials and Methods tential as a potted plant is dependent upon the effective use Asiflorum lily bulbs (14-16 cm circumference) of cultivars 'Clubhouse', 'Modern Style', 'Best Seller', and 'Rodeo' were Florida Agricultural Experiment Station Journal Series No. R-07296. planted three per 15 cm plastic pot (1.5 1) on 16 Feb. 1999.

Proc. Fla. State Hort. Soc. 112: 1999. 277

Asiflorum lily hybrids respond to chemical growth regula tors but at concentrations generally higher than those used for Easter lilies and Asiatic hybrid lilies. They offer growers a new product provided plant height is maintained in propor tion to container size. Further research on increased concen trations of growth regulators and a broader evaluation of new cultivars from European breeders will further define the po tential of this crop for Florida growers.

Literature Cited

Anonymous. 1998. Height control for potted L.A. hybrid lily bulbs: Crop 1998. Fact Sheet, Fred C. Gloeckner & Co., New York, NY. 2 pp. Bailey, D. A. and W. B. Miller. 1989. Whole-plant response of Easter lilies to ancymidol and uniconazole. J. Amer. Soc. Hort. Sci. 114(3):393-396. Ball, J. P. and W. B. Miller. 1996. Preplant bulb dips for height control of L.A. hybrid lilies. So. Nur. Assoc. Res. Conf. 41:20-23. Beattie, D. J. andj. W. White. 1993. Lilium-hybrids and species. Chapter in: The Physiology of Flower Bulbs, ed. by A. De Hertogh and M. Le Neud, Figure 1. Growth regulator effect on Asiflorum lily cv. Clubhouse: left, wa Elsevier Press, New York. pp. 423-454. ter control; right, paclobutrazol drench at 3.0 mg ai/pot. Davis, T. D., G. L. Steffens and N. Sankhla. 1988. Triazole plant growth regu lators. Hort. Rev. 10:63-105. Dicks, J. W., J. M. Gilford, and A. R. Rees. 1974. The influence of timing of application and gibberellic acid on the effects of ancymidol on growth and flowering of mid-century hybrid lily cv. Enchantment. Scientia Hor- showed very little basal necrosis. The flower buds had many tic. 2:153-163. external silvery hairs, which created a 'fuzzy' look. Neither an Funnell, K. A. and R. D. Heins. 1998. Plant growth regulators reduce post cymidol or uniconazole retarded plant growth enough to production yellowing of potted Asiflorum lilies. HortScience yield a plant less than 51 cm tall. Paclobutrazol at 3.0 mg pro 33(6):1036-1037. duced plants 48.2 cm tall. Plants treated at 4.0 mg or 5.0 mg Giafagna, T. J. and G. J. Wulster. 1986. Comparative effects of ancymidol and paclobutrazol on Easter lily. HortScience 21(2):463-464. were too compact to be marketable. Jiao, J., X. Wang and T. J. Tsujita. 1990. Comparative effect of uniconazole 'Rodeo': This was the last cultivar to flower (66.1 days) and drench and spray on shoot elongation of hybrid lilies. HortScience displayed the poorest quality vegetative and floral develop 25(10): 1244-1246. ment. The tulip-like flowers were a medium pink with a clear Johnson, C. R. 1973. Effectiveness of ancymidol on reducing height of Easter cream center but faded rapidly to a pale pink. Petals abscised lilies grown under different environments. Proc. Fla. State Hort. Soc. 86:380-382. prematurely, forming a carpet of pink petals on the bench be Larson, R. A. and R. K. Kimmons. 1971. Results of a new growth regulator. neath the plants. were narrow, medium green, and Flor. Rev. 148:22-23, 54-55. had basal necrosis, especially at the highest growth regulator Simmons, J. A. and B. G. Cumming. 1977. Bulb dip applications of growth concentrations. Stems were weak and often curled downward regulating chemicals for inhibiting stem elongation of 'Enchantment' and 'Harmony' lilies. Scientia Hortic. 6:71-81. from the weight of the flowers. Plants were responsive to an Wilfret, G. J. 1987. Height retardation of Easter lilies grown in containers. cymidol and paclobutrazol but uniconazole concentrations Proc. Fla. State Hort. Soc. 100:379-382. were too low to yield marketable potted plants. Ancymidol at Wilfret, G. J. 1990. Effect of preplant bulb soak with ancymidol or unicona 0.38 mg and paclobutrazol at 2.0 mg yielded plants of the ide zole on growth and development of Easter lily. Proc. Fla. State Hort. Soc. al height. The high temperatures and bright light in the 103:203-206. Wilfret, G. J. 1996. Effect of late growth regulator applications at floral bud greenhouse had a negative effect on this cultivar and it has emergence and stretch on Easter lily development. Proc. Fla. State Hort. questionable value for production in central Florida. Soc. 109:11-14.

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