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  • Author or Editor: Brent K. Harbaugh x
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Interveinal chlorosis of lower (oldest) leaves followed by development of interveinal necrotic spots, marginal necrosis, downward cupping of leaves, and leaf abscission were symptoms of a disorder commonly observed during production of potted pentas. The disorder was determined to be an Fe toxicity problem associated with accumulation of extremely high levels of foliar Fe (649 to 1124 ppm). Cultivars varied in their response to soil-applied Fe-DTPA chelate solutions: `Starburst', `Mauve' and `Ruby Red' were very susceptible, `Pink Profusion' was intermediate, and `White', `Lavender Delight', and `Pink Rose' were resistant. Potted plant production in a root medium with an initial pH of 6.7 ± 0.1 and a end pH of 6.4 ± 0.2 reduced the accumulation of foliar Fe to levels ranging from 59 to 196 ppm and prevented development of significant visual symptoms for all Cultivars.

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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.

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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.

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Trachelium caeruleum has been grown in the United States as a cut flower for about a decade. Only two cultivars, `White Umbrella' and `Purple Umbrella', were readily available for commercial use before 1997, but nine new cultivars became available in the last few years. Comparative performance trials have been lacking for these cultivars in the United States. This trial evaluated 11 cultivars of trachelium for cut flower production performance (vegetative and flowering characteristics) and postharvest longevity. The evaluation was in the spring of 1999 at Bradenton, Fla. (27.4 N, 82.5 W; AHS Heat Zone 10; USDA Cold Hardiness Zone 9b). Plant height for all cultivars except `White Umbrella' was above 30 inches (76 cm), a height required for acceptance as a high quality cut flower. `Summer Lake' had the smallest inflorescence diameter of 3.9 inches (10.0 cm) and `Lake Powell' the largest at 6.1 inches (15.4 cm). `White Umbrella' (160 days from seed to flower) was the earliest to flower and `Lake Powell' (169 days) the last to flower. Vase life was as short as 7 days for `Summer Lake' to as long as 11 days for `White Umbrella'. `Lake Powell' (white color group), `Summer Blue Wonder' (blue color group), and `Lake Superior' (purple color group) had the highest overall rankings.

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Caladium (Caladium ×hortulanum) leaves can be injured at air temperatures below 15.5 °C. This chilling sensitivity restricts the geographical use of caladiums in the landscape, and leads to higher fuel costs in greenhouse production of pot plants because warmer conditions have to be maintained. This study was conducted to develop procedures to evaluate differences among caladium cultivars for chilling sensitivity and to identify cultivars that might be resistant to chilling injury. The effects of two chilling temperatures (12.1 and 7.2 °C) and three durations (1, 3, and 5 days) on the severity of chilling injury were compared for three cultivars known to differ in their sensitivity to low temperatures. Exposure of detached mature leaves to 7.2 °C for 3 days allowed differentiation of cultivars' chilling sensitivity. Chilling injury appeared as dark necrotic patches at or near leaf tips and along margins, as early as 1 day after chilling. Chilling injury became more widespread over a 13-day period, and the best window for evaluating cultivar differences was 9 to 13 days after chilling. Significant differences in chilling sensitivity existed among 16 cultivars. Three cultivars, `Florida Red Ruffles', `Marie Moir', and `Miss Muffet', were resistant to chilling injury. These cultivars could serve as parents for caladium cold-tolerance breeding, and this breeding effort could result in reduced chilling injury in greenhouse production of potted plants, or in new cultivars for regions where chilling occurs during the growing season.

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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'.

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Central Florida has a climate similar to many locations in the southeastern United States and parts of Asia, Europe, and Australia. Thus, Florida is an important testing ground for new bedding plant cultivars not only in the United States, but around the world. The authors evaluated 125 petunia (Petunia ×hybrida) cultivars in replicated class tests at Bradenton, Fla. (lat. 27º4′N, long. 82º5′W) in 2000–04 and at Balm, Fla. (lat. 27º8′N, long. 82º2′W) in 2005–06. In this report they establish petunia classes and cultivar standards for each class, and provide objective plant measurements of vegetative and floral characteristics, and subjective performance ratings. Petunia cultivars were grouped into 73 classes based on the distinguishing characteristics for petunia, which are plant type and height, and flower type, color, and color pattern. Comparisons were made within each class to determine performance and to select a cultivar as the standard for the class—a plant with the highest overall performance rating that can represent the class in future trials against new cultivars. During the initial trials, larger numbers of cultivars were evaluated and eliminated from future comparisons when each class standard was selected. Many flower colors and color combinations, as well as plant types and other distinctive characteristics have been developed for bedding plants. By creating class standards for each distinctive characteristic, better choices over a wider range of classes are available to growers and landscapers in this climate. Cultivars with an outstanding overall performance rating (combined foliage, flower, arthropod feeding symptom, and disease symptom ratings ≥5.5 points on a 1 to 7-point scale) for class standard selections were (floribunda, single mix class) ‘Madness Waterfall Mix’ and [single purple (dark), red-violet class] ‘Madness Magenta’; [grandiflora, single blue (dark) class] ‘Eagle Blue’, (single orange shades/tints class) ‘Ultra Salmon’, and [single purple (dark), red-violet class] ‘Storm Violet’; and [spreading, normal, orange (dark) shades/tints class] ‘Ramblin’ Salmon Capri’, [orange (light) shades/tints class] ‘Ramblin’ Peach Glo’, [pink (dark) class] ‘Wave Pink’, [purple (dark), blue-violet class] ‘Avalanche Lavender’, [purple (light) blue-violet class] ‘Ramblin’ Lavender’, (red class) ‘Avalanche Red Improved’, (rose class) ‘Avalanche Rose Improved’, (white class) ‘Plush White’, and [spreading, tall; blue (dark) class] ‘Wave Blue’. These cultivars would likely perform well in the southern United States or areas of the world with similar heat and cold hardiness zones.

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Florida is one of the top wholesale producers of bedding plants, and in 2003 was ranked fourth in the United States in annual bedding plant production and fifth in potted pansy (Viola ×wittrockiana) and viola (V. cornuta) production. Evaluation of viola cultivars is vital for continued growth of the industry. We evaluated 66 viola cultivars in replicated class tests at the University of Florida's Gulf Coast Research and Education Center at Bradenton from 2000-04 and determined the best-of-class for use 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. Viola cultivars were grouped into classes based on growth habit (standard vs. creeping), flower color, and flower color pattern, and the best cultivar in each class was determined. Cultivars with an outstanding overall performance rating (combined foliage, flower, arthropod feeding symptom, and disease symptom ratings ≥5.5 out of a 7 high scale) for best-of-class selections were: (standard black class) `Sorbet Black Delight'; (standard cream class) `Velour Cream Splash'; (standard mix class) `Babyface Mixture'; (standard orange with purple, red-violet cap class) `Penny Orange Jump-Up'; [standard purple (dark), blue-violet with dark eye and light cap class] `Angel Violet Blotch'; (standard white class) `Penny White'; [standard white face with purple (dark), red-violet cap class] `Skippy White With Violet Wing'; (standard yellow class) `Jewel Lemon Yellow'; (standard yellow with blotch class) `Babyface Yellow'; [standard yellow/white face with purple (dark), blue-violet cap class] `Penny Classic Jump-Up'. Solitary cultivar entries (without comparison) with outstanding performance were: `Angel Frosted Yellow Blotch', `Angel Violet Duet', `Babyface White', `Eryln Purple Yellow', `Four Seasons Yellow With Pink Wing', `Gem Antique Apricot', `Gem Antique Pink', `Gem Antique Lavender', `Hobbit Bilbo Baggins', `Jewel Deep Blue', `Penny Azure Twilight', `Penny Beaconsfield', `Penny Cream', `Penny Orange', `Penny Orchid Frost', `Penny Purple', `Penny Yellow Jump-Up', `Princess Lavender and Yellow', `Princess Purple and Gold', `Rebel Yellow', `Sorbet Coconut Swirl', `Sorbet Icy Blue', `Sorbet Lemon Swirl', `Sparkler Purple Orange Face', and `Sparkler Purple Wing'. These cultivars would likely perform well in the southern U.S. or areas of the world with similar heat and cold hardiness zones.

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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.

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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.

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