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Michael D. Frost, Janet C. Cole, and John M. Dole

Improving the quality of water released from containerized production nurseries and greenhouse operations is an increasing concern in many areas of the United States. The potential pollution threat to our ground and potable water reservoirs via the horticultural industry needs to receive attention from growers and researchers alike. `Orbit Red' geraniums were grown in 3:1 peat:perlite medium with microtube irrigation to study the effect of fertilizer source on geranium growth, micronutrient leaching, and nutrient distribution. Manufacturer's recommended rates of controlled-release (CRF) and water-soluble fertilizers (WSF) were used to fulfill the micronutrient requirement of the plants. Minimal differences in all growth parameters measured between WSF and CRF were determined. A greater percentage of Fe was leached from the WSF than CRF. In contrast, CRF had a greater percentage of Mn leached from the system than WRF during the experiment. Also, regardless of treatment, the upper and middle regions of the growing medium had a higher nutrient concentration than the lower region of medium.

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John M. Dole, Janet C. Cole, and Sharon L. von Broembsen

`Gutbier V-14 Glory' poinsettias (Euphorbia pulcherrima Willd. Ex. Klotzsch) grown with ebb-and-flow irrigation used the least amount of water and produced the least runoff, and plants grown with capillary mats used the greatest amount of water and produced the most runoff, compared to microtube and hand-watering systems. The maximum amount of water retained by the pots and media was greatest for the microtube and ebb-and-flow systems and became progressively lower for the hand-watering and capillary mat systems. The media and leachate electrical conductivity from plants grown with subirrigation systems was higher than those grown with top irrigation. For the two top-irrigation systems (microtube and hand-watering), plants grown with 250 mg N/liter from a 20N-4.4P-16.6K water-soluble fertilizer had greater leaf, stem, and total dry weights than those grown with 175 mg N/liter. The two subirrigation systems (ebb-and-flow and capillary mat) produced plants that were taller and had greater leaf, stem, and total dry weights when grown with 175 than with 250 mg N/liter. The higher fertilizer concentration led to increased N, P, Fe, and Mn concentration in the foliage. Nitrogen concentration was higher in top-irrigated plants than in subirrigated plants. The ebb-and-flow system produced the greatest total dry weight per liter of water applied and per liter of runoff; capillary mat watering was the least efficient in regard to water applied and runoff.

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Janet C. Cole, John M. Dole, and Vicki L. Stamback

Water quality has become a significant issue in the nursery industry. Local testing of runoff contamination from nursery production is, however, of little value to other growers because of the variation in management practices and nursery layouts. Two nursery blocks have been designed and constructed to test runoff from production with sprinkler and drip irrigation systems in combination with constant liquid fertilization and controlled release fertilizers. Management practices using various combinations of irrigation systems with fertilizer application rates are being tested in a small area with reasonable control of inputs. Preliminary data has shown no difference in plant response to irrigation method, but runoff was significantly reduced with drip irrigation. Plant quality was better with controlled release fertilizer, which generally yielded less N and P contamination in runoff, than constant liquid fertilization except during extremely hot weather.

Open access

Cristian E. Loyola, John M. Dole, and Rebecca Dunning

In the United States and Canada, there has been an increase in the demand for local specialty cut flowers and a corresponding increase in production. To assess the needs of the industry, we electronically surveyed 1098 cut flower producers and handlers in the United States and Canada regarding their current cut flower production and postharvest problems, and customer issues. We received a total of 210 responses, resulting in a 19% response rate. The results showed that the main production problem was insect management; crop timing was the second most important problem and disease management was the third. Crop timing encompasses a range of related issues such as determining the correct harvest stage, harvest windows that are too short, flowering all at once, or lack of control when the crop is ready to harvest. The main postharvest problems were temperature management, hydration, and flower food management. Timing and stem length were the two most mentioned species-specific production issues, with each one listed by 10% or more of the respondents for eight of the total 31 species. Regarding on-farm postharvest handling, hydration and vase life were the two most mentioned issues; they were reported for five and three species, respectively. For postharvest during storage and transport, damage and hydration were the most common issues; these were listed for three species each. The most commonly mentioned customer complaints were vase life and shattering, which were reported for six and two species, respectively. These results will allow researchers and businesses to focus on the major cut flower production and postharvest issues and on crops that are most in need of improvement in North America.

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Bridget K. Behe, Paul B. Redman, and John M. Dole

Consumer flower-color preferences are of interest to market researchers, plant producers, and retailers because this information can help them to anticipate accurately the sales product mix. Our objective was to determine consumer bract-color preferences for 47 poinsettia (Euphorbia pulcherrima Willd. ex Klotzsch) cultivars. Visitors (124) to the Franklin Park Conservatory in Columbus, Ohio, rated `Sonora', a red cultivar, highest (4.6 of 5.0) of any cultivar. Nine of ten highest rated cultivars were red. We compared the ratings of poinsettia buyers with those of nonpoinsettia buyers and found only one difference: nonpoinsettia buyers rated `Jingle Bells III', a marble cultivar, higher (4.3) than poinsettia buyers (3.8). We also compared consumers who had purchased a red poinsettia to those who had purchased nonred colors and found that red poinsettia buyers rated `Sonora' higher (4.9) than nonred poinsettia buyers (4.5). Men rated `Red Elegance' higher (3.7) than women (3.3), whereas women rated `Freedom White' higher (3.1) than men (2.4). We found few differences between men and women, buyers and nonbuyers, and nonred buyers and red buyers, which may indicate a relatively homogeneous market that does not greatly differentiate among poinsettia bract color.

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Iftikhar Ahmad, Brian E. Whipker, and John M. Dole

Effects of paclobutrazol and ancymidol on postharvest performance and growth control of potted sunflower (Helianthus annuus L.), zinnia (Zinnia elegans Jacq.) and marigold (Tagetes erecta L.), petunia (Petunia ×hybrida Vilm.) plugs, respectively, were studied. Paclobutrazol was applied as a drench at 0, 1.0, 2.0, or 4.0 mg of a.i. per 15.2-cm pot for sunflower and 0, 0.5, 1.0, or 2.0 mg per 12.5-cm pot for zinnia, while ancymidol was applied at 0, 40, 80, and 160 mg·L−1 with a volume of 0.21 L·m−2 as a foliar spray for marigolds or petunia plug crops. With an increase in paclobutrazol dose or ancymidol concentration, plant growth (plant height and diameter, shoot fresh or dry weight) was controlled for all species tested. Use of 1.0–2.0 mg paclobutrazol per pot produced 21% to 28% shorter plants with 12% to 15% smaller plant diameter, 13% to 19% less shoot fresh weight, 15% to 21% less dry weight, and darker green foliage color for potted sunflower than nontreated plants. Treatment with 1.0–4.0 mg paclobutrazol per pot delayed first wilting by 0.7–1.4 days compared with nontreated plants. For zinnia, 0.5–1.0 mg paclobutrazol controlled plant growth, produced dark green foliage, and extended shelf life by delaying first wilting by 2.6–3.9 days and second wilting by 1.4–2.0 days than nontreated plants. For marigold and petunia plugs, 40–80 mg·L−1 ancymidol provided ample growth control with darker green foliage; however, postharvest longevity was extended only when plugs were sprayed with 160 mg·L−1 ancymidol. During simulated storage and shipping, plant growth retardants maintained darker green foliage for potted sunflower, zinnia, and marigold plugs and prevented postharvest stem elongation of petunia plugs. In summary, use of plant growth retardants effectively controlled excessive plant growth and extended shelf life of potted plants and plugs.

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Jaime K. Morvant, John M. Dole, and Janet C. Cole

Pelargonium ×hortorum Bailey `Pinto Red' plants were fertilized with equal amounts of N, P, and K derived from: 1) 100% constant liquid fertilization (CLF); 2) 50% CLF plus 50% controlled-release fertilizer (CRF); or 3) 100% CRF per pot and irrigated using hand (HD), microtube (MT), ebb-and-flow (EF), or capillary mat (CM) irrigation systems. The treatment receiving 100% CRF produced greater total dry weights, and released lower concentrations of NO3-N, NH4-N, and PO4-P in the run-off than the 100% CLF treatment. The percentage of N lost as run-off was greatly reduced with the use of CRF. MT irrigation produced the greatest plant growth and HD irrigation produced the least. The EF system was the most water efficient, with only 4.7% of water lost as run-off. Combining the water-efficient EF system with the nutrient-efficient CRF produced the greatest percentage of N retained by plants and medium (90.7) and the lowest percentage of N lost in the run-off (1.7).

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Nathan J. Jahnke, John M. Dole, and H. David Shew

Postharvest environments during storage and shipping are often conducive to plant stress and disease development. Liners of four cultivars of geraniums (Pelargonium ×hortorum) were evaluated every 2 days for their susceptibility to gray mold (Botrytis cinerea) and leaf yellowing over an 8-day simulated shipping period at either constant air temperature of 15 °C or variable air temperatures cycling every 24 hours between 10 and 30 °C. The latter treatment was created using air temperature logs of commercial liner shipments sent to five locations during Spring 2016 and Fall 2016. We sprayed a spore suspension of 2 × 104 or 2 × 106 to inoculate liners before they were subjected to the two temperature treatments. Disease ratings did not reach significant levels for the dry control until day 6 of storage. Regardless of the spore concentration, ratings were similar for inoculated cuttings. Independent of the storage temperature and spore concentration, liners developed minor lesions by day 2 of storage. Cultivars varied slightly in disease ratings, with Tango Dark Red being the most susceptible, followed by Patriot Bright Red, Patriot Rose Pink, and Americana Red. During the 8-day incubation period, ‘Patriot Rose Pink’ developed the most leaf yellowing compared with the other three cultivars. Liners that experienced variable air temperatures had marginal leaf yellowing by day 2, and this yellowing increased throughout the experiment. Liners placed at 15 °C had ≈50% less leaf yellowing compared with liners exposed to variable air temperatures until day 8, when leaf yellowing was similar between the two air temperature treatments. Disease caused by B. cinerea was avoided when simulated shipping was 2 days or fewer, and a stable air temperature of 15 °C reduced leaf yellowing on geranium liners compared with variable air temperatures.

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John M. Dole, Zenaida Viloria, Frankie L. Fanelli, and William Fonteno

Vase life of ‘Karma Thalia’ dahlia (Dahlia ×hybrida), ‘Lace Violet’ linaria (Linaria maroccana), ‘Sunrise’ lupine (Lupinus hartwegii ssp. cruickshankii), ‘Temptress’ poppy (Papaver nudicaule), ‘Indian Summer’ rudbeckia (Rudbeckia ×hybrida), ‘Jemmy Royal Purple’ trachelium (Trachelium caeruleum), and ‘Benary's Giant Scarlet’ and ‘Sun Gold’ zinnias (Zinnia elegans) was determined after being subjected to postharvest handling procedures. Cut dahlia, lupine, poppy, rudbeckia, trachelium, and ‘Sun Gold’ and ‘Benary's Giant Scarlet’ zinnia flowers could be held in unamended tap or deionized (DI) water with no effect on vase life. Vase life of linaria was longest when placed in DI water with 8-hydroxyquinoline citrate and a solution pH of 3.5. A vase solution of 2% sucrose without foam extended consumer vase lives for linaria, trachelium, and ‘Benary's Giant Scarlet’ zinnia. Floral foam or 2% or 4% sucrose had no effect on the consumer vase life of dahlia, lupine, rudbeckia, and poppy. Trachelium and rudbeckia did not tolerate a 20% sucrose treatment for 24 h, whereas linaria and ‘Benary's Giant Scarlet’ zinnia had a longer vase life with a 10% sucrose pulse than a water-only pulse. For trachelium, the longest (17.5 days) consumer vase life occurred when the Chrysal Professional 2 Processing solution (CP2) was used after pretreatment with DI water. Either of two commercial holding solutions, CP2 or Floralife Professional (FLP), similarly extended the vase life of linaria. The use of FLP or CP2 improved consumer vase life of dahlia, lupine, and poppy compared with DI water. Dahlia, trachelium, and zinnia flowers could not be cold stored at 2 °C. Lupine and poppy could be stored at 2 °C wet or dry for 2 weeks. Linaria and rudbeckia could be cold stored for 3 weeks. Lupine and trachelium were susceptible to 1 μL·L−1 exogenous ethylene, which induced floret abscission in lupine and stopped floret opening in trachelium. 1-Methylcyclopropene and silver thiosulfate similarly suppressed the ethylene effect. Cut linaria, zinnia, dahlia, rudbeckia, and poppy flowers were unaffected by exogenous ethylene.

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Ben A. Bergmann, John M. Dole, and Ingram McCall

Increasing cut stem length and reducing crop production time are producers’ goals for numerous cut flower species. One or both of these aims was met in several field-grown cultivars through foliar application of gibberellic acid (GA3), but effectiveness varied by cultivar, application rate, and timing. Of the 13 cultivars tested, stem length was increased in nine cultivars [Toreador Red celosia (Celosia argentea), Camelot White foxglove (Digitalis purpurea), Imperial Giants Pink Perfection larkspur (Larkspur hybrids), Compliment mix lobelia (Lobelia hybrids), Nippon Taka ornamental pepper (Capsicum annuum), Amazon Neon Duo and Bouquet Purple sweet william (Dianthus hybrids), Summer Pastels yarrow (Achillea millefolium), and Benary’s Giant Scarlet zinnia (Zinnia elegans)], and time to harvest was decreased in four cultivars [High Tide White ageratum (Ageratum houstonianum), lobelia, ornamental pepper, and zinnia], when GA3 was applied as a foliar spray. Concentrations of 400, 800, and 1600 mg·L−1 GA3 were most effective. Application of GA3 resulted in malformed or smaller flowers or lighter green foliage in foxglove, lobelia, sweet william, and zinnia. In most cases, only one application was tested, and greatest response to GA3 was observed during 3–6 weeks post application. Gibberellic acid did not influence stem length in three cultivars [High Tide White ageratum, Aurora Deep Purple delphinium (Delphinium hybrids), and Column Lilac Lavender stock (Matthiola incana)], and decreased flower stem length in one cultivar (High Tide Blue ageratum). Four cultivars were identified as good candidates for further research given their promising responses to GA3 treatments.