`Nellie White' Easter lily bulbs (Lilium longiflorum Thunb.) were given 6 weeks of 5.5C, placed in the greenhouse, and divided into groups based on number of days to emergence: 0 to 6, 7 to 13, 14 to 20, or 21 to 27 days. At emergence, the shoots received 0, 1, 2, or 3 weeks of long days (LDs). The experiment was repeated for 3 consecutive years. Late-emerging plants had fewer days from emergence to visible bud and anthesis than early-emerging plants. Consequently, late-emerging plants flowered within 3 to 11 days of early emerging plants despite 16 to 22 days difference in emergence time. Late-emerging plants were tallest, while plants emerging in the second week had the most leaves. Flower count was not influenced by emergence date in Year 1. In Year 2, flower count decreased curvilinearly with later emergence. In Year 3, flower count was highest in plants emerging in the second week and lowest in the last week. Increasing LDs decreased the number of days from emergence to visible bud and anthesis but increased plant height. LDs did not affect leaf count in any year or flower count in Years 1 and 2. In Year 3, flower count increased with increasing weeks of LDs. LD × emergence date interactions existed, but varied from year to year.
John M. Dole
`Blenda', `Leen v.d. Mark', `Monte Carlo', `Negritta' and `Paul Richter' tulip (Tulipa gesneriana) bulbs received a total of 15 weeks of cold (5°C) with 0, 2, 4, 6, 8, 10, or 12 weeks applied to dry, unpotted bulbs. The bulbs were then planted, watered, and exposed to cold for the remainder of the 15 weeks. Bulbs receiving up to 10 weeks dry, unpotted cold showed no decrease in flowering percentage and plant quality when compared to bulbs receiving 15 weeks of moist, potted cold. For bulbs receiving 12 weeks of dry cold, flowering percentage was generally lower when compared with 0-10 weeks of dry cold and varied with the cultivar and the year, i.e. 63% of `Paul Richter' and 100% of `Negritta' bulbs receiving 12 weeks of dry cold flowered in year one: whereas, 95% of `Paul Richter' and 70% of `Negritta' bulbs flowered in year two. For all cultivars, bulbs receiving 12 weeks of dry cold had the shortest shoots at the end of the cooling treatment compared with the other treatments. While final height varied significantly with the cultivar in year two, differences were not commercially noticeable. Final height was not influenced in year one.
John M. Dole
John M. Dole
Three cut-flower species, Ageratum houstonianum `Tall Blue Horizon', Antirrhinum majus `Spring Giants Mix', and Helianthus annuus `Sunrich Orange' were grown in 806, 1801, or 1001 bedding plants flats resulting in 32 (85), 86 (280), and 156 (620) cm2 (mililiter medium)/plant, respectively. Plants were sown Sept. 1997 (fall), Dec. 1997 (winter), or Mar. 1998 (spring). Increasing area per plant decreased number of stems harvested but increased percent of stems harvested for all species. Increasing area per plant increased stem length and selling price for Antirrhinum and Helianthus; no significant difference was noted for Ageratum. Days to anthesis decreased with later planting for Antirrhinum and Helianthus; however, for Ageratum winter planting had the longest crop time and spring planting the shortest. Gross profit per square meter and square meter per week increased with decreasing area per plant for Ageratum and Helianthus; no significant difference was noted for Ageratum. Gross profit per square meter per week increased with later planting for all species. With all species 806 flats or spring planting required frequent irrigation, which would best be supplied by an automated irrigation system. Experiment was repeated in 1998/1999 using Carthamus tinctorius `Lasting Yellow', Celosia argentea `Chief Mix', Cosmos bipinnatus `Early Wonder', Helianthus annuus `Sunbright, Tagetes erecta `Promise Orange' and `Promise Yellow', and Zinnia elegans `Giant Deep Red' and `Oklahoma Mix'.
Theresa Bosma and John M. Dole
Various postharvest treatments were evaluated for effect on longevity and quality of cut Campanula medium L. `Champion Blue' and `Champion Pink' stems. Stems stored at 2 °C either wet or dry had no difference in vase life or percent flowers opened; however, flowers stored dry had a slightly greater percentage of senesced flowers at termination. Increasing storage duration from 1 to 3 weeks decreased vase life. Stems pretreated for 4 hours with 38 °C floral solution (deionized water amended to pH 3.5 with citric acid and 200 mg·L-1 8-HQC) or a 1-MCP pulse followed by a 5% sucrose pulse solution produced the longest vase life (10.3 or 10.4 days, respectively). Flowers opening after treatments commenced were paler than those flowers already opened and a 24-hour pretreatment with 5% or 10% sucrose did not prevent this color reduction. Stems had an average vase life of only 3.3 days when placed in floral vase foam but lasted 10.0 days without foam. Optimum sucrose concentration was 1.0% to 2.0% for stems placed in 22 °C floral vase solution without foam and 4% for stems placed in foam. High (110 μmol·m-2·s-1) or low (10 μmol·m-2·s-1) light levels did not affect postharvest parameters, but the most recently opened flowers were paler under low light conditions than under high light conditions. Chemical names used: 8-hydroxyquinoline citrate (8-HQC); 1-methylcyclopropene (1-MCP).
Lane Greer and John M. Dole
Six defoliants were applied in fall and tested for their efficacy in preharvest defoliation of fieldgrown curly willow (Salix matsudana `Tortuosa'), american bittersweet (Celastrus scandens), and american beautyberry (Callicarpa americana). Defoliants included acetic acid, chelated copper, crop oil concentrate surfactant (COC), ethephon, dimethipin plus COC, pelargonic acid, and a tap water control. For chelated copper, a concentration of 800 mg·L–1 (ppm) was most effective at promoting defoliation, providing 100% defoliation of american bittersweet and 76% defoliation of american beautyberry. For curly willow and american beautyberry, all concentrations of dimethipin produced good or excellent defoliation. Increasing concentrations of ethephon from 200 to 2500 mg·L–1 increased defoliation from 0% to 67%. Pelargonic acid was not effective at promoting defoliation of woody plants at the concentrations used. In an experiment conducted during spring using containerized curly willow, irrigation was stopped for 0, 3, or 6 days before defoliants were applied, but none of the irrigation treatments promoted defoliation. In a postharvest study using cut curly willow, stems were held in distilled water at 5, 20, or 35 °C (41.0, 68.0, or 95.0 °F) for 1, 3, 5, or 7 days. Holding cut stems of curly willow at 20 °C promoted 68% defoliation, compared to 53% or 28% for 5 or 35 °C, respectively.
Lane Greer and John M. Dole
For decades, vegetable growers have used black polyethylene mulch to warm the soil in early spring, reduce weeds, and conserve soil moisture. Use of plastic mulch can increase crop yields and improve fruit quality. This article reviews research performed with plastic, aluminum foil, aluminum-painted, and degradable mulches. Most research focused on the effects of plastic mulches on insects and viruses they vector, and on yields. Aluminum foil and aluminum-painted mulches are effective at repelling insect pests, especially aphids (Aphididae) and thrips (Thripidae). Yields are often higher with black plastic compared to bare ground. Clear plastic is rarely used in the U.S. because it can encourage weed growth, unless a herbicide or fumigant is used underneath. Colored mulches can increase yields and control pests, but color may be less important than brightness of the mulch or contrast with bare soil. New forms of photodegradable mulches eliminate the need to remove and dispose of plastic at the end of the growing season, but have not been widely adapted because they tend to degrade prematurely.
Iftikhar Ahmad and John M. Dole
Effects of homemade or commercial floral preservatives, applied as 48-hour grower treatment or continuous retailer/consumer application, were studied on cut ‘ABC Blue’ lisianthus (Eustoma grandiflorum), ‘Maryland Plumblossom’ snapdragon (Antirrhinum majus), ‘Mid Cheerful Yellow’ stock (Matthiola incana), and ‘Deep Red’ Benary’s zinnia (Zinnia violacea). Cut stems were placed in solutions containing 500 mL·L−1 lemon/lime soda (soda); 6 mL·L−1 lemon juice plus 20 g·L−1 sugar (lemon juice); 100 mg·L−1 citric acid plus 20 g·L−1 sugar plus 200 mg·L−1 aluminum sulfate (C-AS); 400 mg·L−1 citric acid plus 20 g·L−1 sugar alone (citric acid), or combined with either 0.5 mL·L−1 quaternary ammonium chloride (C-QA), or 0.007 mL·L−1 isothiazolinone (C-IS); 10 mL·L−1 Floralife Clear Professional Flower Food (Floralife); or 10 mL·L−1 Chrysal Clear Professional 2 (Chrysal), dissolved in tap water, which was also used as control without any added compound. Cut stems of lisianthus and stock had longest vase lives (22.1 and 12.7 days, respectively) when placed in C-IS continuously, while snapdragon and zinnia stems had longest vase lives (22.3 and 16.3 days, respectively) when placed in C-QA solution continuously. Continuous use of soda extended vase life of cut lisianthus, snapdragon, and stock stems, but not zinnia, compared with tap water. Citric acid extended the vase life of lisianthus and stock when used continuously and of zinnia when used for 48 hours. Use of C-AS or lemon juice either had no effect or reduced vase life of the tested species, except lemon juice increased zinnia vase life when used as a 48-hour treatment. Stems of lisianthus, stock, and zinnia placed continuously in C-IS, C-QA, or citric acid had high solution uptake. No significant differences were observed for vase life of all tested species with short duration (48 hours) application of solutions, except 48-hour use of citric acid or lemon juice increased zinnia vase life compared with tap water. Overall, continuous vase application of the homemade preservatives resulted in longer vase life extension than 48-hour treatment. Among tested preservative recipes, C-IS, C-QA, soda, or citric acid demonstrated best postharvest performance of tested species. However, recipes containing C-AS or lemon juice had detrimental effects and should not be used for handling cut stems of tested species.