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.
John M. Dole and Harold F. Wilkins
Poinsettia (Euphorbia pulcherrima Wind. ex. Klotzsch) cultivars were divided into free-branching and restricted-branching groups. Auto and reciprocal grafts were made among three free-branching cultivars, Annette Hegg Brilliant Diamond (BD), Annette Hegg Topwhite (TW), and Annette Hegg Hot Pink (HP), and two restricted-branching cultivars, Eckespoint C-1 Red (CR) and Eckespoint C-1 White (CW). when CR scions were grafted onto BD stocks, vegetative characteristics of branching pattern and leaf morphology of CR plants were altered when compared to the control graft combination CR/CR (scion/stock). Branching pattern was determined by pinching the scion above the 12th node and measuring axillary shoot length, diameter, and node number 30 days later. CR scions grafted onto BD stocks produced a plant very similar to BD plants when axillary shoot length and node number were compared. However, axillary shoot diameter and leaf morphology were intermediate between CR and BD plants. Changes were retained after two generations of serial vegetative propagation and are considered permanent. The reproductive characteristics of anthesis date, bract color, and cyathia cluster diameter were not influenced by the stock. CR/BD plants produced twice as many axillary inflorescences as BD/BD or BD/CR plants, while CR/CR plants did not produce any. All of the free-branching cultivars were able to alter the vegetative characteristics of all of the restricted-branching cultivars.
John M. Dole, Paul Fisher and Geoffrey Njue
Several treatments were investigated for increasing vase life of cut `Renaissance Red' poinsettia (Euphorbia pulcherrima Willd. ex Klotzsch.) stems. A vase life of at least 20.6 days resulted when harvested stems were placed directly into vases with 22 °C deionized water plus 200 mg·L-1 8-HQS (the standard floral solution used) and 0% to 1% sucrose without floral foam. Maturity of stems at harvest, ranging from 0 to 4 weeks after anthesis, had no effect on vase life or days to first abscised leaf. Pretreatments immediately after harvest using floral solution heated to 38 or 100 °C, or 1 or 10-min dips in isopropyl alcohol, had no effect, whereas 24 hours in 10% sucrose shortened vase life by 6.4 days and time to first abscised cyathium by 4.5 days. Stem storage at 10 °C decreased vase life, particularly when stems were stored dry (with only 0.8 days vase life after 3 weeks dry storage). Increasing duration of wet storage in floral solution from 0 to 3 weeks decreased vase life from 21.5 to 14.6 days. Placing cut stems in a vase containing floral foam decreased time to first abscised leaf by 3.7 to 11.6 days compared with no foam. A 1% to 2% sucrose concentration in the vase solution produced the longest postharvest life for stems placed in foam but had little effect on stems not placed in foam. A 4% sucrose concentration decreased vase life compared with lower sucrose concentrations regardless of the presence of foam. Holding stems in the standard floral solution increased vase life and delayed leaf abscission compared with deionized or tap water only, with further improvement when stem bases were recut every three days. Commercial floral pretreatments and holding solutions had no effect on vase life and days to first abscised cyathium but delayed leaf abscission.
Frank Blazich Jr. and John M. Dole
Todd J. Cavins and John M. Dole
Narcissus L. `Music Hall', N. `Tahiti', Tulipa L. `Couleur Cardinal', and T. `White Emperor' bulbs were precooled at 5 °C for 0 or 5 weeks and planted 15, 30, or 45 cm deep (from bulb base) into raised ground beds under 0%, 30%, or 60% shade. Plant growth was monitored for two consecutive years after planting. Precooling reduced the percentage of T. `White Emperor' that flowered but did not affect flowering percentage of the other cultivars. Precooling delayed anthesis in one or both years for all cultivars. The greatest percentage of bulbs flowered when planted 15 cm deep and the 45-cm planting depth reduced flowering percentage. Increasing planting depth delayed anthesis for all cultivars. Increasing shade increased stem lengths in one or both years for all cultivars, but did not influence flowering percentage. Perennialization was low for all cultivars regardless of treatment. Cultivar differences in perennialization occurred; in year 2 up to 30% of N. `Tahiti' bulbs flowered vs. 32% for `Music Hall' and up to 30% of T. `White Emperor' bulbs flowered vs. only 22% of `Couleur Cardinal'.
Todd J. Cavins and John M. Dole
Hyacinthoides hispanica (Mill.) Roth., Hyacinthus orientalis L. `Gypsy Queen', Narcissus pseudonarcissus L. `Music Hall', N. pseudonarcissus `Tahiti', Tulipa gesneriana L. `Couleur Cardinal', and T. gesneriana `White Emperor' bulbs were given 0 or 6 weeks of preplant 5 °C cold treatment and planted 15, 30, or 45 cm deep into raised ground beds under 0%, 30%, or 60% shade. Plant growth was monitored for 2 years after planting. Preplant 5 °C cold pretreatment reduced percentage of Tulipa `White Emperor' bulbs that flowered but did not affect the percentage of bulbs that flowered for the other species. Cold pretreatment also delayed anthesis in one or both years for all cultivars except Hyacinthoides hispanica. The greatest percentage of bulbs flowered when planted 15 cm deep. The 45-cm planting depth reduced bulb flowering percentage or eliminated plant emergence. Increasing planting depth increased days to anthesis for all cultivars in both years. Increasing shade increased stem lengths in year 2 for all cultivars except Hyacinthoides hispanica, but did not influence percentage of bulbs flowering for any cultivars. For all cultivars perennialization was low regardless of treatment as less than 30% of bulbs survived to the 2nd year.
Todd J. Cavins and John M. Dole
Campanula medium L. `Champion Blue' (CB) and `Champion Pink' (CP) and Lupinus hartwegii Lindl. `Bright Gems' (LH) were grown in 8- or 16-h initial photoperiods, transplanted when two–three, five–six, or eight–nine nodes developed and placed under 8-, 12-, or 16-h final photoperiods. Greatest flowering percentage (100%) for CB and CP occurred when plants with two–three nodes were grown in the 16-h final photoperiod. The lowest flowering percentage for CB (3.3%) and CP (15.7%) resulted from plants grown in the 8-h photoperiod continuously (initial and final). CB and CP stem lengths (49.8 cm) were longest when grown in the 8-h photoperiod continuously and shortest with the 16-h initial and 8-h final photoperiods for CB (26.5 cm) and the 16-h photoperiod continuously for CP (25.4 cm). Fewest days to anthesis, 134 days for CB and 145 days for CP, resulted from the 16-h photoperiod continuously and greatest (216 days) from the 8-h photoperiod continuously. LH plants had a high flowering percentage (99.6%) regardless of photoperiod or transplant stage. Stem lengths were longest (60.1 cm) for LH plants exposed to the 16-h photoperiod continuously and shortest (46.2 cm) when exposed to the 8-h photoperiod continuously. LH exhibited a curvilinear response for days to anthesis with the 16-h final photoperiod producing the shortest crop time (166 days) and the 12-h final photoperiod producing the longest crop time (182 days). The experiment was repeated in 1998/1999 with high intensity discharge (HID) lighting during the initial photoperiod which increased plant quality.
Todd J. Cavins and John M. Dole
Campanula medium L. `Champion Blue' and `Champion Pink' and Lupinus hartwegii Lindl. `Bright Gems' were grown in 8- or 16-h initial photoperiods, transplanted when 2-3, 5-6, or 8-9 true leaves developed, and placed under 8-, 12-, or 16-h final photoperiods. The lowest flowering percentage for `Champion Blue' (<1%) and `Champion Pink' (16%) resulted from plants grown in the 8-h photoperiod continuously. One hundred percent flowering occurred when Campanula were grown in the 16-h final photoperiod, indicating that `Champion Blue' and `Champion Pink' are long-day plants. Plants grown initially in the 8-h and finished in the 16-h photoperiod had the longest stems. Stem diameter was generally thickest for plants grown in the 8-h compared with the 16-h initial photoperiod. However, the 8-h initial photoperiod delayed anthesis compared with the 16-h initial photoperiod. `Champion Blue' and `Champion Pink' plants transplanted at the 2-3 leaf stage from the 16 hour initial to the 8-h final photoperiod had flowering percentages of 64% and 63%, respectively; however, when transplanted at the 8-9 leaf stage, plants were fully mature and 100% flowering occurred indicating that all plants were capable of flowering. In year 2, plants receiving high intensity discharge (HID) supplemental lighting during the 16-h initial photoperiod reached anthesis in 11 fewer days compared with plants not receiving HID supplemental lighting. High profits were obtained from Campanula grown in the 8-h initial photoperiod and transferred at 5-6 true leaves into the 16-h final photoperiod. Lupinus hartwegii plants had a high flowering percentage (96% to 100%) regardless of photoperiod or transplant stage. The 16-h final photoperiod decreased days to anthesis compared with the 8- or 12-h final photoperiod indicating that L. hartwegii is a facultative long-day plant. Increasing length of final photoperiod from 8- to 16-h increased stem length. Juvenility was not evident for Lupinus in this study. In year 2, Lupinus cut stems were generally longer and thicker when given HID supplemental lighting, especially when grown in the 8- or 12-h final photoperiod. Supplemental lighting also reduced days to anthesis. Highest profits were generally produced from Lupinus plants grown with supplemental HID lighting (during the initial photoperiod) until 8-9 true leaves had developed.
John M. Dole and Harold F. Wilkins
The free-branching poinsettia (Euphorbia pulcherrima Willd. ex. Klotzsch) cultivar Annette Hegg Brilliant Diamond (BD) contained a free-branching agent that was graft-transmissible to the restricted-branching cultivar Eckespoint C-1 Red (CR). CR plants were transformed by the agent regardless of whether BD plants were used as scion or stock, indicating that the agent moved basipetally and acropetally through the graft union. The agent was repeatedly transmitted to a CR plant by serial grafting with a free-branching poinsettia plant. A minimum of 10 days contact through grafting was required for BD plants to transmit the agent to CR plants. Percentage of CR plants exhibiting the free-branching characteristic increased from 0% for < 10 days of graft contact with BD plants to 100% after 30 days.
John M. Dole and Michael A. Schnelle
Floricultural producers, cut flower wholesalers, mass market retailers and general retailers were surveyed to compare and contrast the industry in terms of attitudes and problems. Questions involved general business information, as well as specific crops. Overall, all four segments of the industry were neutral to negative on potted flowering plants, but were positive to neutral on bedding and foliage plants. However, producers were slightly negative concerning the postharvest life of bedding plants. While cut flower wholesalers had a positive attitude concerning cut flowers, retailers and mass marketers tended to be neutral to negative. In particular, retailers and mass marketers felt cut flowers were too expensive and too short lived. Floral preservatives were used by 81.6% of general retailers, while only 18.8% of mass market retailers used preservatives. All cut flower wholesalers used preservatives. Capital availability and market demand were the factors most limiting to expansion for producers and general retailers; mass market firms listed competition as their most limiting factor. Results from other questions will also be provided.