Search Results
You are looking at 31 - 40 of 69 items for
- Author or Editor: Brent K. Harbaugh x
Annual bedding plants comprised 50% of the $4.6 billion wholesale value of United States floricultural crops in 2000. Florida is one of the top wholesale producers of bedding plants in this industry, and in 2000 was number one in the production of potted marigolds. Evaluation of marigold cultivars is vital for continued growth of the industry. We evaluated 84 cultivars of african marigold (Tagetes erecta) and french marigold (T. patula) in replicated class tests at the University of Florida's Gulf Coast Research and Education Center at Bradenton, Fla. (lat. 27°4' N, long. 82°5' W; AHS Heat Zone 10; USDA Cold Hardiness Zone 9b) in Fall 1999. In this report, we provide objective plant measurements of vegetative and floral characteristics as well as six weekly subjective ratings. Subjective ratings were on a 1 to 7 scale with the highest rating of 7 for excellent. In general, cultivars with vegetative and floral ratings ≥5 were considered outstanding, 4 to 4.9 as good performers, and ≤3.9 as fair to poor. These ratings permit readers to evaluate foliage and floral characteristics at different times during the season, and to evaluate performance over time. Cultivars were grouped into classes based on species, plant height, flower type, and flower color. Outstanding cultivars (those cultivars with an overall rating ≥5) and their class were: `Inca Gold' and `Royal Gold' [african marigold (African)—gold class]; `Mesa Orange' and `Royal Orange' (African— orange class); `Inca Yellow', `Mesa Yellow', and `Perfection Yellow' (African—yellow class); `Disco Granada' [french marigold (French) dwarf—single gold/red class], `Disco Flame' (French dwarf—single red/gold class); `Golden Boy' and `Hero Gold' (French dwarf—double gold class); `Bonanza Orange', `Orange Boy', `Girl Orange', `Jacket Orange' (French dwarf—double orange class); `Yellow Boy', `Girl Primrose', and `Jacket Yellow' (French dwarf—double yellow class); `Harmony Boy' (French dwarf— double orange/red class); `Hero Flame' (French dwarf—double red/orange class); `Bonanza Flame Improved' (French dwarf—double red/yellow class); `Legend Gold' (French double— gold class); `Legend Orange Improved' (French—double orange class); `Spry Boy' (French double—yellow/red class); `Durango Bee', `Durango Red', and `Hyper Red/Yellow' (French— double red/yellow class). We believe these cultivars would perform well in the southern U.S. or areas of the world with similar heat and cold hardiness zones.
Nonplanted Caladium × hortukmum Birdsey `Candidum' tubers were exposed to 26 (control), 38,43, or 48C for 1,2, or 3 days. Then tubers were planted and forced in a glasshouse for 4 weeks at 18 to 33C (air). Leaf emergence from tubers exposed to 48C for 1 or 2 days required 3-12 days longer than leaf emergence from control tubers. No leaves emerged from tubers treated at 48C for 3 days. Exposing tubers to 38C for 3 days or 43C for 1 day did not affect subsequent plant growth. Exposing tubers to 43C for 2 or 3 days or 48C for 1 or 2 days resulted in plants with reduced shoot fresh weights and fewer leaves ≥ 15 cm. In a second experiment, planted tubers were forced for 10 days at 26C so that roots had developed to the edge of the pot and shoots had emerged to the soil surface. These planted (sprouting) tubers were exposed to 43C for 0,4,8,12,16,20, or 24 hours/day for 1,3, or 5 days and then forced for 7 weeks in a glasshouse. With 3- or 5-day treatments, days to leaf emergence increased as the hours of exposure to 43C increased. Only 33% of planted tubers exposed to 43C for 24 hours/day for 5 days sprouted. Tubers exposed to 43C for≤ 12 hours/day for 3 days produced plants of similar or greater height, numbers of leaves □≥15 cm wide, and shoot fresh weights, but additional hours of daily exposure decreased these plant characteristics. At 5 days, plant height, number of ≥ 15-cm-wide leaves, and shoot fresh weight decreased linearly with increased hours of exposure of tubers to high temperature.
Abstract
Foliar-bract calcium (Ca) sprays and fertilization practices that altered Ca availability and supply were evaluated for their effect on marginal bract necrosis incidences of ‘Gutbier V-14 Glory’ poinsettia (Euphorbia pulcherrima Willd.). About 90% fewer marginal necrotic lesions were observed on plants receiving an 81% NO3-N and 903-ppm Ca soluble fertilizer with 10% of the total nutrients foliar-applied than on plants grown with medium-applied Osmocote 19N-2.6P-10K (47% NO3-N) or with medium-applied liquid fertilizer containing 30% or 65% NO3-N and 0 ppm Ca. Addition of 354 ppm Ca in a 53% NO3-N, or 964 ppm Ca in a 75% NO3-N medium-applied fertilizer did not significantly reduce the number of lesions compared to the same fertilizer with 0 ppm Ca or the equivalent rate of a 53% NO3-N Osmocote 14N-6.1P-11.6K. Weekly foliar-bract sprays of 432 ppm Ca from Ca(NO3)2·4H2O reduced numbers of lesions by 94% (<1.5 lesions per plant), regardless of fertilization practice. Thus, soil applications of Ca were not effective in preventing marginal bract necrosis, whereas foliar applications of Ca were highly efficacious.
Fusarium crown and stem rot, caused by Fusarium avenaceum (Fr.: Fr.) Sacc., is a serious disease of lisianthus [Eustoma grandiflorum Raf. (Shinn.)]. While more than 80 new cultivars of lisianthus have been released for sale in the United States in the last decade, there is a lack of information on their susceptibility to this pathogen. Forty-six cultivars of lisianthus were evaluated for their response to infection by F. avenaceum. Cultivars were grouped according to blue/purple, pink, or white flower colors and evaluated within their color class. Although some plants of all cultivars were susceptible to F. avenaceum, partial resistance was observed as indicated by differences in the length of time to symptom expression and in the frequency of diseased plants within each color group. In 21 of the 46 cultivars, 80 to 100% of the plants expressed symptoms within 55 days after inoculation. The lowest frequencies of diseased plants 55 days after inoculation were found in `Ventura Deep Blue' and `Hallelujah Purple' (25%), `Bridal Pink' (23%), and `Heidi Pure White' (53%) for the blue/purple, pink, and white flower color groups, respectively. Screening cultivars for resistance to F. avenaceum is the first step in breeding resistant cultivars. The methods we developed for these studies should be useful in screening for resistance. These results also may help growers select cultivars that are less susceptible to F. avenaceum, which should aid in the management of this disease.
Abstract
Eight lacewing (Chrysopa earned) larvae per greenhouse snapdragon (Antirrhinum majus), released 4 at a time twice during 8 weeks effectively controlled aphids (Myzus persicae). Two initial sprays of malathion and nicotine sulfate 1 week apart followed by release of 4 lacewing larvae per plant also were effective. Flowers produced under chemical or biological control systems were equal in quality. Lacewing larvae in a 21°C greenhouse required a week longer to effectively control aphids than those in a 24°C greenhouse.
The ornamental value of caladium (Caladium ×hortulanum Birdsey) depends to a large extent on its foliar characteristics. Efficient genetic improvement of caladium foliar characteristics requires a good understanding of the inheritance of these traits, including leaf shape, color, and spots. This study was conducted to determine the inheritance of leaf spots in caladium and to understand their relationships with leaf shape and main vein color. Eighteen controlled crosses were made among eight commercial cultivars expressing red or no leaf spots, and progeny of these crosses were observed for segregation of leaf spots as well as leaf shape and vein color. A single locus with two alleles is shown to be responsible for the presence or absence of leaf spots in caladium, with the presence allele (S) dominant over the absence allele (s). The major spotted commercial cultivar Gingerland is heterozygous for this trait. Leaf spots are inherited independently from leaf shape, but they are closely linked with the color of the main leaf veins. The recombination frequencies between the leaf spot locus and the main vein color locus ranged from 0.0% to 8.9% with the crosses or the parental cultivars used, with an average of 4.4%. Leaf spots and vein colors represent the first linkage group of ornamental traits in caladium and possibly in other ornamental aroids. The knowledge gained in this study will be valuable when it comes to determine what crosses to make for development of new cultivars. It may be also useful to those interested in determining the inheritance of similar traits in other ornamental plants, including other ornamental aroids such as dieffenbachia (Dieffenbachia Schott).
Seedlings of commercial lisianthus cultivars form rosettes when grown at 25 to 28°C. Rosetted plants have a basal cluster of leaves, very short internodes typical of biennials, and do not bolt or flower for months without being exposed to 3 to 4 weeks at <15 to 18°C to reverse heat-induced rosetting. Semirosetted plants develop when seedlings are grown at a constant 22 to 25°C or at <22°C night with >28°C day. Semirosetted plants have one or more side shoots which may elongate and flower, but plants flower unpredictably and are of poor quality as cut flowers or potted plants. `Maurine Blue' and Florida Blue' were released from the Univ. of Florida in 1995. To our knowledge, they are the first heat-tolerant lisianthus cultivars. Seedlings and plants can be grown at 28 to 31°C without rosetting. `Maurine Blue' ranged in height from 38 cm (summer) to 67 cm (spring) during 1994 and 1995 production trials in Florida. `Maurine Blue' has potential for use as a tall bedding plant if sold as green transplants, a flowering potted plant if grown with three plants per 15-cm-diameter pot with a growth retardant, or as a bouquet-type cut flower. `Florida Blue' plants (38 cm) grown in an 11.5-cm square pot (0.65-L) with capillary mat irrigation were similar in height to `Blue Lisa' (32 cm) and taller than `Little Belle Blue' (22 cm) and `Mermaid Blue' (24 cm). `Florida Blue' was designated as a semi-dwarf cultivar with an intended use as a bedding plant. Growth retardants would be useful for production in pots <10 to 12 cm in diameter. Complete descriptive information, photographs and pedigrees will be presented.