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- Author or Editor: Brent K. Harbaugh x
Distribution of the greenhouse whitefly and its wasp parasite, were measured on 12 cultivars of tomato, Lycopersicon esculentum Mill., by counting populations of parasitized and nonparasitized whitefly nymphs per leaflet. Parasitism percentages· were similar on all cultivars despite large differences in whitefly populations. Second generation parasite populations correlated significantly with whitefly numbers (r=0.71**). “Pocketing” behavior significantly influenced whitefly distribution with minimal cultivar preference. However, distribution gradients showed that ‘Floradel’ was the center of 2 large pockets, indicating preference for it.
Lisianthus [Eustoma grandiflorum (Raf). Shinn.] is emerging as an important cut flower in the United States while in European and Asian markets it is already listed among the top ten cut flowers. Many new cultivars have been released in the United States within the last 5 years, but comparative performance trials of these cultivars have been lacking. This trial evaluated 47 cultivars of lisianthus representing series (cultivar groups) that were marketed in the United States in 1998. Evaluations were made for rosetting, plug performance, cut-flower characteristics (vegetative and flowering attributes) as well as postharvest longevity of cut flowers. Significant differences among cultivars were found for all of the attributes evaluated. `Malibu Purple', `Catalina Blue Blush', and `Alice Pink' were selected as the best performers in the seedling (plug) stage since they had less than 5% rosettes, large leaves and a vigorous root system. Cultivars were placed in classes based on flower color, flower size, and number of petals (single or double flowers). Cultivars were ranked for each of the attributes and the total rank sum of all attributes (TRS) was used to select the best in class. Cultivars selected as best in class were `Malibu Purple', `Malibu Blue Blush', `Alice Purple', `Balboa Blue', `Avila Blue Rim', `Mellow Pink', `Flamenco Wine Red', `Flamenco Rose Rim', `Alice Pink', `Avila Rose' and `Echo Pink', `Alice White', and `Mariachi White'.
Phosphorus is considered a major pollutant of lakes in central Florida, and growers producing crops in the Lake Okeechobee watershed are being challenged to reduce use of P fertilizer. Caladium (Caladium×hortulanum Birdsey) tubers are produced on organic soils within this area. This study was done to determine if current commercial P fertilization rates could be reduced or eliminated, since these organic soils have high levels of water extractable P (Pw). Two farms were selected with low (Farm A 19 lb/acre; 21 kg·ha-1) or high (Farm B 59 lb/acre; 66 kg·ha-1) preplant Pw levels. Production of caladium tubers with the standard grower P fertilization practice (Farm A = P at 39.2 lb/acre; 43.9 kg·ha-1, or Farm B = P at 15.9 lb/acre; 17.8 kg·ha-1) was compared to production with either one-half the standard grower rate of P or no P. The percentage of harvested tubers in each of five grades and the estimated harvested tuber value index were similar irrespective of the amount of P fertilizer used on either farm. These results indicate that P could be eliminated from the fertilization program for caladium tuber production on organic soils.
Nicotine sulfate and resmethrin, applied at recommended rates, were less toxic to adults and larvae of Encarsia formosa than were endosulfan, malathion, or naled. Adult parasites were killed by contact with any of the 5 chemicals. Endosulfan and malathion left residues toxic to adult E. formosa for 2 to 3 weeks; malathion and naled killed many 10- to 15-day-old parasite larvae. The potential uses of nicotine sulfate and resmethrin were shown in theoretical models for integrated control of greenhouse whitefly.
Caladium (Caladium ×hortulanum Birdsey) is an important aroid widely used in the ornamental plant industry. Concerns have been raised about possible loss of genetic diversity due to a drastic decline in the number of cultivars in the last century. This study assessed genetic diversity and relationships among caladium cultivars and species accessions. Forty-five major cultivars and 14 species accessions were analyzed based on 297 DNA fragments produced by the target-region amplification polymorphism marker system. A low level of diversity (44.4% polymorphism) was exhibited in cultivars, while a high level of diversity (96.8% polymorphism) was present among seven accessions of Caladium bicolor (Aiton) Vent., Caladium marmoratum Mathieu, Caladium picturatum C. Koch, and Caladium schomburgkii Schott. A small percentage (7.6%) of DNA fragments was present in cultivars but absent in the seven species accessions, while a high percentage (32.2%) of DNA fragments was present in the seven species accessions but absent in cultivars. Cultivars shared a higher level of similarity at the molecular level with an average Jaccard coefficient at 0.802, formed a large group in cluster analysis, and concentrated in the scatter plot from a principal-coordinate analysis. Two accessions of C. bicolor and C. schomburgkii were very similar to cultivars with Jaccard similarity coefficients from 0.531 to 0.771, while the rest of the species accessions had small similarity coefficients with cultivars (0.060 to 0.386). Caladium steudnirifolium Engler and Caladium lindenii (André) Madison were very dissimilar to C. bicolor, C. marmoratum, C. picturatum, and C. schomburgkii, with Jaccard similarity coefficients from 0.149 to 0.237 (C. steudnirifolium) and from 0.060 to 0.118 (C. lindenii). There is a limited amount of molecular diversity in caladium cultivars, but the great repertoire of unique genes in species accessions could be used to enhance the diversity in future cultivars and reduce potential genetic vulnerability.
Three lisianthus [Eustoma grandiflorum (Raf.) Shinn.] cultivars 0, 10, 17, 24, or 31 days from sowing were grown in 28C soil for 0, 7, 14, 21, or 28 days to determine the effects of high temperature during seedling growth on the development of rosetted plants. Increasing the duration of high-temperature exposure increased the percentage of rosetted plants for all cultivars. Such exposure for 28 days resulted in 96%, 93%, and 18% rosetted plants for cultivars Yodel White, Yodel Pink, and GCREC-Blue, respectively. Seedling age did not affect percentage of flowering `Yodel Pink' plants, but as seedling age increased to 31 days, the percentage of flowering plants increased with `GCREC-Blue' and decreased for `Yodel White'. In a second experiment, four lisianthus cultivars were grown at 22C for 3 weeks and then exposed for 28 days to soil at 22, 25, 28, or 31C. Increasing soil temperature resulted in more rosetted plants for all cultivars. With soil at 31C, 83%, 58%, 19%, and 2% of the seedlings rosetted for the cultivars USDA-Pink, Yodel White, Little Belle Blue, and GCREC-Blue, respectively.
Florida is one of the top wholesale producers of bedding plants, and in 2003 was ranked fourth in annual bedding plant production and fifth in potted pansy/viola production. Evaluation of pansy cultivars is vital for continued growth of the industry. We evaluated 210 cultivars of pansy (Viola ×wittrockiana) (164 new cultivars) in replicated class tests at the University of Florida's Gulf Coast Research and Education Center at Bradenton, Fla., from 2000–04 to determine the best-of-class and use them in future trials to compare against new entries in the same class. In this report, we provide objective plant measurements of vegetative and floral characteristics as well as subjective performance ratings. Subjective ratings were on a 1 to 7 scale with the highest rating of 7 for excellent. In general, overall performance ratings (combined foliage, flower, arthropod, and disease ratings) ≥5.5 were considered outstanding. Pansy cultivars were grouped into classes based on flower color and pattern. Best-of-class selections that had an outstanding overall performance rating in one or more contested trials, never falling below 5.0 in other contested trials, were: (black class) `Accord/Banner Black Beauty', (blue shades/tints class) `Nature Blue', (blue with blotch class) `Nature Ocean', (mix class) `Panola Clear Mixture', (pink shades/tints with blotch class) `Nature Pink Shades', [purple (dark), blue-violet with white cap class] `Nature Beacon', [purple (dark), blue-violet/white face with blotch class] `Panola Purple With Face', (purple with light eye class) `Baby Bingo Lavender Blue', (white class) `Nature White', (yellow class) `Nature Yellow', (yellow with blotch and purple, blue-violet cap class) `Iona Purple & Yellow With Blotch', (yellow with blotch and red cap class) `Bingo Red & Yellow', (yellow with blotch and red cap class) `Panola Yellow With Blotch', (yellow with dark veins class) `Whiskers Yellow'. We believe these cultivars would perform well in the southern U.S. or areas of the world with similar heat and cold hardiness zones.
Cultivated caladiums are valued for their bright colorful leaves and are widely used in containers and landscapes. More than 1500 named cultivars have been introduced during the past 150 years, yet currently only about 100 cultivars are in commercial propagation in Florida. Caladium tubers produced in Florida account for 95% of the world supplies. Loss of caladium germplasm or genetic diversity has been a concern to future improvement of this plant. In addition, the relationship among the available cultivars, particularly those of close resemblance, has been lacking. This study was conducted to assess the genetic variability and relationship in commercial cultivars and species accessions. Fifty-seven major cultivars and 15 caladium species accessions were analyzed using the target region amplification polymorphism marker technique. This marker system does not involve DNA restriction or adaptor linking, but shares the same high throughput and reliability with the amplified fragment length polymorphism system (AFLP). Eight primer combinations amplified 379 scorable DNA fragments among the caladium samples. A high level of polymorphism was detected among the species accessions as well as among cultivars. These markers allowed differentiation of all the cultivars tested, including those hardly distinguishable morphologically. Clustering analysis based on these DNA fingerprints separated the cultivars into five clusters and Caladium lindenii far from other caladium species. The availability of this information will be very valuable for identifying and maintaining the core germplasm resources and will aid in selecting breeding parents for further improvement.
Host-plant nutritional status may affect the incidence and development of western flower thrips (WFT; Frankliniella occidentalis Pergande). Two greenhouse experiments were conducted to determine the responses of WFT population levels on impatiens (Impatiens wallerana Hook.f.) when plants were fertilized with commercially practiced rates of nitrogen (N) and phosphorus (P). Impatiens `Dazzler Violet' were grown with nutrient treatment combinations of 2 N rates (8 and 20 mm) by 2 P rates (0.32 and 1.28 mm). Individual plants grown in thrips-proof cages were inoculated with WFT at 2 or 4 weeks after transplant, in separate experiments, representing vegetative or reproductive stages of plant growth, respectively. Plants were destructively sampled weekly for 4 weeks following inoculation. Plant tissue N and P concentrations were significantly different across treatments: 8 and 20 mm N resulted in 4.9% and 6.3% N in tissue, respectively; 0.32 and 1.28 mm P resulted in 0.37% and 0.77% P in tissue, respectively. Nitrogen rates had no effect on WFT population levels. However, 4 weeks after inoculation with adult female WFT during the vegetative growth stage, plants fertilized with 1.28 mm P had more adult WFT than those fertilized with 0.32 mm P. Feeding damage varied depending on whether plants were inoculated in the vegetative stage with adult WFT or during reproductive growth with immature WFT. Plant size and number of flowers were lower in plants inoculated during the vegetative growth stage with adult WFT but were not affected when inoculation with immature WFT occurred during the reproductive stage, as most WFT were found feeding inside the nectariferous spurs of the flowers. Tissue N was lower in WFT-inoculated plants compared to noninoculated plants in both experiments.