May 2004

University of Florida’s Best By Rick Kelly, Rick Schoellhorn, Zhanao Deng and Brent K. Harbaugh

Growers around the country face a decision when producing bedding plants for the Deep South and similar climates around the world. There, flowers may flourish year-round; however, the moderate to high temperatures and ample moisture fuel the fires of disaster, as plant pests also thrive under these conditions. Plants bred and evaluated elsewhere may not meet the challenges faced in hot and humid climates. This decision may also exist between market choice and garden performance. A consumer may abandon a species that had eye appeal, but later proved to have poor landscape performance.

Our mandate is to determine landscape performance of seed-propagated annuals in comprehensive replicated trials. Cultivars to be evaluated are placed into classes by species, flower and foliage color, plant height and growth habit. Two duplicate fields are planted. One field is scouted and sprayed, as needed. Plant measurements, performance, flowering data and cultivar performance are evaluated there. The other field is not sprayed, and pest symptom ratings are taken there. Pathologists and entomologists diagnose pests when necessary. Data is recorded over the course of the season and analyzed to provide unbiased statistical comparisons. Average ratings for foliage and flower quality, pests and plant death from soil-borne pathogens are utilized for an overall performance rating. We pick only one cultivar in each class to be “best-of-class” based on this rating. We use this cultivar to compare new entries in each new trial. If the new entry performs better, it takes the best-of-class position; if only one plant is entered in a class, it becomes the uncontested best-of-class. We cooperate with four of Florida’s premier public gardens to display the best-of-class selections in their formal landscapes for public display.

We produce our own plugs to ensure uniform plants with the same history are available for planting. Spring trial plugs are moved to the field in late March or early April into raised fumigated beds covered with plastic mulch. Each plant is fertilized with 2 tsp. Osmocote Plus 15-3.9-9.9 fertilizer (15-9-12 slow-release type with micronutrients, The Scotts Co.). Only the sprayed field is drenched with fungicides.

1999 through 2003

Following are the spring/fall crops with the highest ratings from trial evaluations from 1999 through 2003 and why they excelled. Many cultivars are new and some are “old timers” that continue to be the best and await new competition in 2004. Refer to Figures 1, 2 and 3, below and pages 52, 54 and 56 and www.gpnmag.com for the list of these cultivars, days to first flower and flower diameters. Ageratum houstonianum. ‘Fields Blue’ and ‘Hawaii Shell Á Pink’ had more flowers early in the season, less stem lodging and less insect/mite damage than other cultivars.

Platycodon grandiflorum. Different cultivars were evaluated in separate spring trials, and losses occurred, but ‘Miss Tilly Blue’ survivors had good foliage/flower ratings all season without pests above the ground.

Rudbeckia hirta. ‘Toto Rustic’ had the best flowering all season. Worm damage on foliage and thrips-like flower feeding were observed, but only the latter was serious on a yellow cultivar.

Torenia fournieri. Naturally, the “Florida pansy,” does well here, with uncontested ‘Duchess Deep Blue’, Pink and Burgundy producing very good to excellent flowers on very full and uniform plants.

Alternanthera dentata. ‘Purple Knight’ had mounds of rich, dark red-violet foliage 14 inches high. Leafrollers fed on foliage but had no impact. (see also Iresine).

Iresine herbstii. ‘Purple Lady’, an amaranth of similar color to Brazilian joyweed, is also a good foliage plant. Unlike Purple Knight, as the plant matures, it remains low growing. Leafroller damage was evident but was never unacceptable. Whitefly adults were seen in very large numbers, but no nymphs.

Canna x generalis. ‘Tropical Yellow’ produced attractive yellow blooms with deep orange flecks. Plants were sturdy, compact and pest free. When allowed to grow as a perennial, rust was a problem between fall and winter. Older bleached flowers should be removed to leave an attractive display.

Celosia spicata. ‘Spiky Pink’ (dwarf with wheat-like flower spikes) and ‘Prestige Scarlet’ (tall, with cockscomb flowers) both had full, rather uniform plants with good flower displays and no plant death.

Hibiscus moscheutos. ‘Luna Blush’ and Red were uncontested marsh mallows. They had huge flowers that were not hidden by the foliage (especially Luna Blush). Full and uniform plants measured about 24 1?2 inches. Cucumber beetles fed on the foliage and flowers, and whitefly infested leaves but with little impact.

Nierembergia hippomanica. ‘Mont Blanc’ was uncontested, with good overall performance and outstanding flowering in mid-May, remaining good in early June. Powdery mildew was diagnosed, but symptoms were minimal.

Dianthus barbatus, D. barbatus interspecific, D. interspecific. ‘Amazon Neon Purple’, Neon Cherry, Rose Magic, ‘Bouquet Purple’, ‘Diamond Mixed’, ‘Dynasty Purple’, Red, White Blush, ‘Melody Pink’, Blush Pink, White and ‘Noverna Purple’ were not impacted by heat and disease. The Dynasty, Amazon and Melody cultivars produced very sturdy and uniform plants with many high-quality flowers. Armyworm feeding scars and disease spots were minor.

Begonia semperflorens-cultorum. ‘Harmony White’, ‘Prelude Pink’, ‘Olympia Sprint Mix’, ‘Vodka Cocktail’, ‘Lotto White’, ‘Eureka Bronze Leaf Rose’ and ‘Eureka Green Leaf Scarlet’ were the best in the bronze and green leaf classes. They had better plant and flower uniformity, fuller plants and fewer dead plants as temperatures rose.

Nicotiana x alata. ‘Saratoga Antique Shades’ and Mixture were uncontested and outstanding. Symptoms of larval feeding, mites, leaf spots, leafminers and graymold on flowers were minimal.

Pelargonium x hortorum. ‘Horizon Red’, Scarlet, Coral Spice, ‘Maverick Star’, Light Salmon, Orange Appeal and White had the best flowering and plant development in the spring and winter trials. Worm feeding, foliar lesions, Botrytis blight and wilt from soil-borne pathogens were not serious problems for these cultivars.

Gomphrena globosa. ‘Bi-color Rose’, good for landscape and cut or dried flowers, was the uncontested best-of-class. No plants died, nor did worm feeding or foliar lesions become significant.

Impatiens wallerana. Double-flowered class: ‘Tutu Natural Rose’ and Salmon; single-flowered class: ‘Dazzler Orange’, Violet, ‘Accent Apricot’, Watermelon, Violet Star, Red, Coral Star, White, ‘Stardust Salmon’, Rose, ‘Infinity Salmon’, ‘Impact Orange’, Red, Scarlet, Formula Mix, Lavender and Rose Pink. These had the best foliage and flower characteristics and were least affected by soil-borne pathogens, Botrytis on flowers, Alternaria on foliage, two-spotted spider mite or thrips on flowers and foliage.

Eustoma grandiflorum. Double-flowered class: ‘Sapphire Double White’; single-flowered class: ‘Sapphire Blue Chip’ and ‘Forever White’. Foliage fullness and uniformity, lack of lodging, superior flower numbers and quality, and less pests (primarily whiteflies and armyworms) resulted in higher ratings for these selections. Fusarium crown rot affected this crop but was variable.

Tagetes erecta. Dwarf: ‘Atlantis Mixture’, ‘Inca II Gold’ and ‘Royal Orange’. Good African marigolds exhibited similar foliage/flower traits compared to French types, with stem strength to support large flowers in wind and rain, good flower display and condition in the presence of graymold, especially with large flowers that today are bred to be hidden (but not forgotten) beneath new growth.

Tagetes patula. Single-flowered tall class: ‘Disco Flame’, Granada, Mix and Red; double-flowered dwarf and tall classes: ‘Hero Flame’, ‘Janie Gold’, ‘Durango Tangerine’, Bee, ‘Orange Boy’, ‘Little Devil Fire’, ‘Yellow Boy’, ‘Spry Boy’, ‘Marvelous Flame’, Yellow, ‘Legend Gold’, Orange and Spry displayed the best stem strength, had full and dense foliage, the flower display and condition were excellent even in the presence of graymold, and there were minimal effects from mites, worms, thrips and soil-borne pathogens.

Tagetes tenuifolia. ‘Luna Lemon Yellow’ is uncontested, with good to excellent flowering all through the fall (November to mid-December). Salvia farinacea. ‘Blue Signum’ had significantly better flower performance than other entries.

Melampodium paludosum. ‘Melanie’ and ‘Lemon Delight’ had very full and uniform foliage with good to excellent flowering all season. Worms, mites and a few leafminers, leaf spots and scattered occurrences of powdery mildew on foliage were very minor.

Portulaca grandiflora. ‘Sundial Fuchsia’, Gold and Peach had full foliage and good flowering by early June.

Pennisetum glaucum. ‘Purple Majesty’, uncontested, was good to excellent all season. Plants had very good basal branching with very uniform rich, deep purple foliage. Foliage color shifted to an olive green cast with some rust present late in season, but, overall, the plant remained attractive.

Capsicum annuum. ‘Chilly Chili’ had the highest foliage and fruit-quality ratings, with very full foliage, good fruit number and good fruit color. Other entries had unacceptable ratings late in the season. No foliage pests were detected. Pepper weevil did infest the fruits of all these cultivars; however, the effect on the appearance of the ornamental fruit display during the rating period was minimal.

Petunia x hybrida. Good performers with the highest ratings in their class had the fullest, most uniform foliage and flowers and the least pest problems. Floribundas: ‘Double Madness Pink’, ‘Celebrity Mid Blue’, Chiffon Morn, Rose, White, ‘Magenta Madness’ and ‘Waterfall Madness Mix’; grandifloras: ‘Aladdin Cherry’, Strawberry Ice, ‘Blue Storm’, ‘Eagle Pastel Pink’, White, ‘Lavender Storm’, ‘Pink Storm Morn’, ‘Ultra Pastel Pink’, Salmon, ‘Violet Storm’, ‘White Storm’ and ‘Wild Rose Mix’; millifloras: ‘Fantasy Light Lavender’ and Mix; multifloras: ‘Symphony Light Blue’, Pink, Violet, Deep Rose, Á Rose, Rose Star, Salmon, White, ‘Primetime Violet Star’ and ‘Hurrah Pink Chiffon’; spreading: ‘Avalanche White’, ‘Easy Wave Salmon’, Shell Pink, ‘Explorer Rose’, ‘Opera Light Purple’, ‘Ramblin Deep Salmon’, Pink, Lavender, Violet, ‘Wave Blue’ and ‘Wave Pink’.

Phlox drummondii. ‘Grammy Pink/White’, and ’21st Century Patriot Mix’ took the heat and flowered well all season. Armyworms and thrips were minor.

Phlox cuspidata. ‘Crystal Mix’ was the only pointed phlox evaluated, but excellent foliage and good flowering will keep it on top.

Salvia splendens. ‘Fire Star’, ‘Sizzler Burgundy Stripe’, Burgundy Halo, ‘Picante Salmon’, ‘Salsa Rose Bicolor’, ‘Landscaper Bright Scarlet’, ‘Gardenleader Rose’, ‘Rookie Scarlet’, ‘Blue Ribbon’ and ‘Salvador Red’ were the best from a large focus trial conducted in 1999. New entries evaluated since have not replaced these best-of-class varieties.

Spilanthes oleracea. ‘Peek-A-Boo’ produces very full and rather uniform plants with interesting foliage and very good flowering in late May. Worm feeding was minor, but mites were more serious late in the season. This is a unique plant that can be used as a focal point in the landscape.

Helianthus annuus. ‘Starburst Lemon Éclair’ has a unique pale yellow flower (pollen free) with dark center that might resemble a dahlia on a plant about 3 feet tall. It had good ratings for foliage and flower quality.

Gazania rigens. ‘Kiss Bronze’, Bronze Star, Orange, Mahogany, White, Golden Yellow and ‘Frosty Kiss Mix’ had the best flower display throughout the season with less two-spotted spider mite, leaf spots and mildew.

Verbena x hybrida. ‘Merlot Mix’ performed well in April. By late May, performance was fair; however, other entries did not do as well, having too many dead plants, mildew and mites. Moss verbena ‘Serenity Mix’ [Verbena tenuisecta (speciosa)] had outstanding flowers and very full foliage without pest problems. Tuberous vervain or sandpaper verbena ‘Santos’ (Verbena rigida) was great in winter/early spring trials with uniform, floriferous and sturdy plants. The tough, rigid foliage attracted many white flies and their nymphs (not evident in winter/early spring trials) in spring, yet not too much foliage damage occurred, and flower numbers remained good.

Catharanthus roseus. Normal growth habit class: ‘First Kiss Icy Pink’, ‘Heatwave White’, ‘Lavender Halo Cooler’, ‘Stardust Mix’, ‘Sunstorm Lilac’, Pink, ‘Victory Apricot’, Cranberry, ‘Vitesse Lavender’ and Rose; trailing class: ‘Cascade Appleblossom’. Fusarium crown rot was diagnosed as the causal agent that destroyed many plants. The only other pests have been flower thrips and Botrytis; no Phytophthora has been diagnosed. These selections held up the best under those conditions.

Z. hybrida. ‘Profusion Orange’, Red and White had good overall performance; by late May white had the best ratings, while cherry formed open gaps, and flower fading was more evident. Worm feeding, leafminers and leaf spots were minor, and no mildew was seen.

Z. elegans. Dwarf classes: ‘Zinnita Orange’, Yellow, ‘Swizzle Cherry/Ivory’, and Scarlet/Yellow did not have mildew, while Zinnitas had numerous mites on 1?3 of the plots and Swizzles did not, though other crops had them; tall class: All Sun cultivars had mildew in late May, but ‘Sun Red’ had a better overall performance due to superior foliage/flower ratings.

Z. angustifolia. ‘Crystal Orange’, White and Yellow are the only entries for this species, producing full foliage and numerous flowers; some plant death and leaf and flower spots have occurred sporadically.

Things to Come

In May 2004, our new spring trial will be in full bloom. Many companies have entered new cultivars. In January 2005, we are moving to a new 400-acre facility in Balm, Fla., to continue our research alongside other research programs that have served growers for over 75 years. Visit the center’s Web site to find out more: http://gcrec.ifas.ufl.edu/.

Author’s Note: The information in this report is a summary of experimental results and does not provide recommendations for crop production. Where trade names are used, no discrimination is intended or endorsement implied.

We’d like to thank Florida Agricultural Experiment Station and all of the companies who provided donations of money, seed and fertilizer. We thank Joyce Jones, Jenna Adams, Paulette Blanchard, Gail Bowman, Kari VanHoose and Nancy West for their technical support.