Flurprimidol Preplant Bulb Soaks Control Growth of Potted Liliums

Abstract

In a series of experiments, flurprimidol (Topflor, SePRO Inc., Carmel, Indiana, USA) was applied as a preplant bulb soak to determine its efficacy on growth control of 'Star Gazer' oriental lily (Lilium hybrids), 'Nellie White' Easter lilies (Lilium longiflorum), and vigorously growing tiger lilies (Lilium lancifolium). Emergence date was noted, and the plants were measured at bloom for plant height, plant diameter, and flower number. Optimal concentrations varied by species. Preplant bulb soaks of flurprimidol at 25 to 400 mg L-1 were applied to 'Star Gazer', and a concentration of 25 mg L-1 resulted in plants 47.7 cm tall, which were 22.7% shorter than the untreated control. 'Orange Tiger' lily bulbs were hydrated in 17°C water for 1 h, allowed to drain 1 h, given 10-min soaks of 0 to 160 mg L-1 flurprimidol, and then allowed to drain for 1 h prior to potting. Flurprimidol at 10 to 20 mg L-1 controlled plant stretch. Plants were transplanted into a field, and no residual effect of flurprimidol preplant bulb soaks were found on the second year growth. Rates were confirmed with three additional L. lancifolium cultivars, and cultivar response varied with 10 to 20 mg L-1 being effective for 'Pink Tiger' and 'Yellow Tiger' while 10 mg L-1 was excessive for 'White Tiger'. 'Nellie White' Easter lilies were more responsive to flurprimidol preplant bulb soaks than other lily cultivars. Optimal concentrations were in the range of 1 to 2 mg L-1 flurprimidol for 9/10 sized bulbs. Not pre-soaking the bulbs in water or prolonged soaking (≥64 min) the bulbs in flurprimidol increased the plant growth regulator efficacy for 'Nellie White'.

Substrate Drenches Containing Flurprimidol Suppress Height of ‘Nellie White’ Easter Lilies

“…While we have found no literature reporting the use of flurprimidol substrate drenches for controlling height of easter lily, previous reports have demonstrated the effectiveness of flurprimidol using a variety of application methods on lilies (Krug et al, 2005a;Pobudkiewicz and Nowak, 1992;Pobudkiewicz and Treder, 2006;Whipker, 2004;Whipker et al, 2011). Krug et al (2005a) reported that applying 0.5 mg flurprimidol per pot provided commercially acceptable height control for 'Star Gazer' oriental lilies with no significant effect on time to anthesis or flower bud number.…”

“…Similarly, height of 'Mona Lisa' oriental lilies was less than untreated plants when flurprimidol was applied as a foliar spray once or twice at concentrations ranging from 10 to 40 mgÁL -1 when shoots were 7 or 14 cm tall (Pobudkiewicz and Treder, 2006). Whipker et al (2011) reported that while preplant bulb soaks in flurprimidol solutions were effective in suppressing stem elongation of 'Nellie White' easter lilies, however variation in responses year-to-year and among different bulb lots made it difficult to identify a recommendation for bulb soak concentration for commercial production. However, flurprimidol bulb soaks have been reported to be a viable PGR application to control height of other lily species and cultivars (Krug et al, 2005a, Whipker et al, 2011.…”

“…Whipker et al (2011) reported that while preplant bulb soaks in flurprimidol solutions were effective in suppressing stem elongation of 'Nellie White' easter lilies, however variation in responses year-to-year and among different bulb lots made it difficult to identify a recommendation for bulb soak concentration for commercial production. However, flurprimidol bulb soaks have been reported to be a viable PGR application to control height of other lily species and cultivars (Krug et al, 2005a, Whipker et al, 2011. For instance, soaking 'Star Gazer' bulbs in solutions containing 25 mgÁL -1 produced commercially acceptable plants that were 14.2 cm shorter than control plants (Krug et al, 2005a), while solutions containing ‡50, 200, or 400 mgÁL -1 flurprimidol resulted in excessive height suppression, delayed time to emergence and anthesis, or reduced flower bud number, respectively, compared with untreated plants (Krug et al, 2005a).…”

“…For instance, soaking 'Star Gazer' bulbs in solutions containing 25 mgÁL -1 produced commercially acceptable plants that were 14.2 cm shorter than control plants (Krug et al, 2005a), while solutions containing ‡50, 200, or 400 mgÁL -1 flurprimidol resulted in excessive height suppression, delayed time to emergence and anthesis, or reduced flower bud number, respectively, compared with untreated plants (Krug et al, 2005a). Whipker et al (2011) reported that while PGR solutions containing 10-20 mgÁL -1 flurprimidol resulted in desirable height control of 'Orange Tiger', 'Pink Tiger', and 'Yellow Tiger' tiger lilies, 'White Tiger' was more sensitive and soak solutions containing <10 mgÁL -1 flurprimidol are required; flurprimidol had no effect on time to anthesis or flower bud number for any tiger lily cultivar (Whipker et al, 2011).…”

“…Flurprimidol substrate drenches effectively suppressed the height of bulb crops such as tulip [Tulipa gesneriana (Krug et al, 2005b)], narcissus [Narcissus pseudonarcissus (Krug et al, 2006)], and lilies including Asiatic lily (Lilium •asiatica), oriental lily (L. auratum • L. speciosum), and tiger lily (L. lancifolium) (Krug et al, 2005a;Pobudkiewicz and Nowak, 1992;Pobudkiewicz and Treder, 2006). While flurprimidol has been shown to have heightsuppressing activity on easter lily when applied as a foliar spray (Whipker, 2004) and bulb dips (Whipker et al, 2011), we have found no reports of using flurprimidol substrate drenches to control height of easter lilies. Therefore, the objective of this research was to quantify how flurprimidol substrate drenches applied to 'Nellie White' easter lilies affect height at flowering, time to flowering, and flower number.…”