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Open access

Heather Kalaman, Gary W. Knox, Sandra B. Wilson, and Wendy Wilber

As land-use patterns change over time, some pollinating insects continue to decline both in abundance and diversity. This is due, in part, to reductions in floral resources that provide sufficient nectar and pollen. Our overall goal is to help increase the use of plants that enhance pollinator health by providing research-based information that is easily accessible to the public. To assess the most successful mode of sharing this information, a survey was distributed to more than 4000 Master Gardener (MG) volunteers of Florida. The objectives of our survey were to gauge both knowledge and interest in common pollinators, common pollinator-friendly floral resources, and a favored means of accessing material about additional pollinator-friendly plants for landscape use. With a response rate of just over 18%, results showed that there is a clear interest among Florida MGs in learning more about pollinators and pollinator-friendly plants with face-to-face classes followed by a website as the preferred modes of accessing educational materials on this topic. Respondents on average were extremely interested in learning more about pollinator plants [mean of 4.41 out of 5.0 (sd = 0.89)], with greatest interest in butterflies/moths (Lepidoptera), followed by bees (Hymenoptera), birds (Aves), bats (Chiroptera), and beetles (Coleoptera). Overall, MG participants felt more confident (P < 0.0001) in their knowledge of pollinator-friendly plants (mean 3.24 out of 5.0) than pollinator insects (mean 3.01 out of 5.0). When tested, 88.5% were able to correctly identify black-eyed susan (Rudbeckia hirta), with 70.1% correctly identifying spotted beebalm (Monarda punctata). Variations were observed in tested knowledge of pollinating insects, with 90.2% correctly identifying a zebra longwing (Heliconius charithonia) and only 32.6% correctly identifying a striped-sweat bee (Agapostemon splendens). These results revealed that MGs perceived themselves to be fairly knowledgeable about both pollinator plants and pollinating insects, yet their tested knowledge ranged widely depending on the actual plant and pollinator type. This suggests an emphasis be given for future MG training focused on diverse plant and pollinator species, preferably in a face-to-face environment. Results also show that additional resources regarding pollinator-friendly plants, as well as identification material on pollinating insects, are both desired and valued by our Florida MG community.

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Kimberly A. Moore, Amy L. Shober, Gitta S. Hasing, Christine L. Wiese, Geoffrey C. Denny, and Gary W. Knox

Recent research suggested that the nitrogen (N) fertilizer rates needed to maintain high-quality landscape plants was lower than rates needed to grow the largest size plants. Our objective was to evaluate the effect of N fertilizer rate on the aesthetic quality of various landscape-grown annual and perennials species. Nineteen cool-season annuals, 20 warm-season annuals, and 4 perennials were planted into raised beds containing subsoil fill material in a completely randomized design in west-central Florida (U.S. Department of Agriculture hardiness zone 9b). Plants were fertilized every 12 weeks with polymer coated, slow-release N (42N–0P–0K) fertilizer at annual N rate of 3, 5, or 7 lb/1000 ft2 (annuals) or 1, 3, or 5 lb/1000 ft2 (perennials). Plants were rated for aesthetic quality every 6 weeks for a period of 18 weeks (annuals) or 54 weeks (perennials). For most species, quality ratings of plants fertilized with 3 lb/1000 ft2 of N per year (annuals) or 1 lb/1000 ft2 of N per year (perennials) were not significantly lower than plants receiving higher rates of N annually. Previously reported N fertilizer recommendations for central Florida of 2 to 4 lb/1000 ft2 per year should be adequate for maintaining acceptable quality landscape-grown annual and herbaceous perennial plant species.

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Matthew R. Chappell, Sarah A. White, Amy F. Fulcher, Anthony V. LeBude, Gary W. Knox, and Jean-Jacques B. Dubois

In 2014, the Southern Nursery Integrated Pest Management (SNIPM) Working Group published both print and electronic versions of IPM for Shrubs in Southeastern U.S. Nursery Production: Volume I. Five hundred print books (of 3000 copies) were distributed to commercial ornamental growers and extension educators in return for their participation in a follow-up survey. The survey was administered to determine the value of book contents, savings that growers realized from using the book, perceived value of the book had users been asked to pay for it, and demographic information. The survey response rate was 46.2%, with respondents from 18 states. Of 243 respondents, 194 (79.8%) had used the book. Entomology information was most used and most useful, followed by plant pathology, weed science, and cultural information. Collective savings attributed to book use totaled $408,832/year for the 194 nurseries that used the book. Applying the use rate (79.8%) identified in this survey, this represents $5.62 million in savings per year for the 3000 printed books, of which 2394 are estimated to have been used. Savings varied by the type and size of operation. Larger operations had greater savings per year. Container growers saved $44.15/acre and field growers $28.37/acre. The price that growers were willing to pay for the book also varied by operation type and size. Extension educators and growers were willing to pay an average of $41.20, with an additional $0.063/acre for container growers and $0.126/acre for field growers. Return on investment for the U.S. Department of Agriculture grant funding for the project was $187.60 per dollar of funding. This survey demonstrates that collaborative efforts can produce high-value deliverables with significant regional and/or national impact.

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Gitta Shurberg, Amy L. Shober, Christine Wiese, Geoffrey Denny, Gary W. Knox, Kimberly A. Moore, and Mihai C. Giurcanu

Current nitrogen (N) fertilizer recommendations for landscape-grown ornamentals are based on limited research. The objective of this research was to evaluate plant response of selected warm- and cool-season annuals to N fertilizer applied at five rates in the landscape. Three warm-season annual species [‘Profusion Cherry’ zinnia (Zinnia elegans ×angustifolia), ‘Cora White’ vinca (Catharanthus roseus), and ‘Golden Globe’ melampodium (Melampodium divaricatum)] and three cool-season annual species [‘Telstar Crimson’ dianthus (Dianthus chinensis), ‘Delta Pure Violet’ pansy (Viola wittrockiana), and ‘Montego Yellow’ snapdragon (Antirrhinum majus)] were transplanted into raised beds containing subsoil fill in U.S. Department of Agriculture (USDA) hardiness zone 9a. Slow-release N fertilizer was applied over an 18-week period at an annual N rate of 0, 2, 4, 6, and 12 lb/1000 ft2. Trials were replicated a second year. Plant size index (SI), tissue chlorophyll (SPAD), and plant quality were determined every 6 weeks. Shoot biomass and tissue total Kjeldahl N (TKN) were determined at 18 weeks. Regression analysis indicated that all species required N inputs at annual rates exceeding 8 lb/1000 ft2 to achieve maximum size, shoot biomass, or SPAD. However, acceptable quality plants were produced at much lower N rates. We suggest application of N fertilizer at a rate of 4 to 6 lb/1000 ft2 per year to landscape-grown annuals to maintain acceptable plant quality and growth. We expect fertilization at lower rates (based on aesthetics) can reduce the amount of fertilizer applied and the potential for nutrient losses in runoff or leachate. Future research should address N fertilization needs in higher fertility soils as well as the response of other plant species.

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Gitta Shurberg, Amy L. Shober, Christine Wiese, Geoffrey Denny, Gary W. Knox, Kimberly A. Moore, and Mihai C. Giurcanu

There is limited research regarding proper fertilization rates and timing for landscape-grown herbaceous perennials. Most current nitrogen (N) fertilizer recommendations for landscape-grown perennials are based on rates for woody landscape plants or on rates for greenhouse-grown perennials. In addition, most fertilizer guidelines are defined to achieve peak growth, which may not be the best indicator of desirable plant quality. Basing fertilizer input rates on plant quality levels rather than maximum growth may result in a lower fertilizer application rate and a reduction in excess fertilizer available for leaching. The objective of this research was to evaluate the response of landscape-grown herbaceous perennials to N fertilizer applied at five rates. Five herbaceous perennials [bush daisy (Gamolepis chrysanthemoides), ‘New Gold’ lantana (Lantana ×hybrid), ‘Mystic Spires’ salvia (Salvia longispicata ×farinacea), ‘Evergreen Giant’ liriope (Liriope muscari), and ‘White Christmas’ caladium (Caladium bicolor)] were transplanted into raised landscape beds containing subsoil fill in U.S. Department of Agriculture (USDA) hardiness zone 9a. Controlled-release N fertilizer was applied at an annual N rate of 0, 2, 4, 6, and 12 lb/1000 ft2 for 96 weeks. Plant size index (SI), tissue chlorophyll, and plant quality were measured every 6 weeks for 96 weeks. Flower cover was determined every 6 weeks from 42 to 96 weeks. Shoot biomass and tissue total Kjeldahl N (TKN) were measured at 96 weeks after planting (WAP). Regression analyses suggested that some species required in excess of 12 lb/1000 ft2 N to reach maximum size, chlorophyll content, and shoot biomass. However, plants exhibited quality ratings of good to excellent at annual N rates of 2 to 4 lb/1000 ft2 N per year. We suggest that these low to moderate levels of N fertilization (2 to 4 lb/1000 ft2 N per year) will provide sufficient N to produce acceptable size and quality herbaceous perennials in the landscape.

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Amy L. Shober, Kimberly A. Moore, Nancy G. West, Christine Wiese, Gitta Hasing, Geoffrey Denny, and Gary W. Knox

Despite inconsistent reports of nitrogen (N) fertilization response on growth of landscape-grown woody ornamentals, broad N fertilization recommendations exist in the literature. The objective of this research was to evaluate the growth and quality response of three landscape-grown woody shrub species to N fertilizer. Three ornamental shrub species, ‘Alba’ indian hawthorn (Raphiolepis indica), sweet viburnum (Viburnum odoratissimum), and ‘RADrazz’ (Knock Out™) rose (Rosa) were transplanted into field soils in central Florida (U.S. Department of Agriculture hardiness zone 9a). Controlled-release N fertilizer was applied at an annual N rate of 0, 2, 4, 6, and 12 lb/1000 ft2 for 100 weeks. Plant size index measurements, SPAD readings (a measure of greenness), and visual quality ratings were completed every month through 52 weeks after planting (WAP) and then every 3 months through 100 WAP. Plant tissue total Kjeldahl N (TKN) concentrations and shoot biomass were measured at 100 WAP. Results of regression analysis indicated little to no plant response (size index, biomass, SPAD) to N fertilizer rate. Shrub quality was acceptable for all species through 76 WAP regardless of the N fertilization rate. However, quality of rose and sweet viburnum fertilized with N at the low rates (<2 lb/1000 ft2) was less than acceptable (<3 out of 5) after 76 WAP. Results suggest that posttransplant applications of fertilizer may not increase plant growth, but that low-to-moderate levels of N fertilization (2 to 4 lb/1000 ft2 per year) may help plant maintain quality postestablishment.

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Amy L. Shober, Kimberly A. Moore, Gitta S. Hasing, Christine Wiese, Geoffrey C. Denny, and Gary W. Knox

Research supporting recommendations for fertilizer needs of landscape-grown vines and groundcovers is lacking. The objectives of our study were to (1) evaluate the quality response of selected vine and groundcover species to nitrogen (N) fertilization at five rates and (2) validate the recommended N fertilizer rates (from the initial evaluation) by monitoring quality of additional landscape-grown vine and groundcover species. Three vine species and two groundcover species were planted in west-central Florida into raised beds containing subsoil fill material in a completely randomized design. Plants were fertilized every 6 weeks with a controlled release fertilizer (20N–0P–0K–23S) at an annual N rate of 0, 2, 4, 6, or 12 lb/1000 ft2. Plant aesthetic quality (0–5 scale) was assessed every 6 weeks for 30 weeks after planting. Although quality of some species increased significantly as N rate increased, all plants supplied with at least 4 lb/1000 ft2 per year N fertilizer had acceptable quality ratings of 3 or better. Screening of three additional vines and four additional groundcovers fertilized with controlled release fertilizer (42N–0P–0K) at an annual N rate of 3, 5, or 7 lb/1000 ft2 confirmed that fertilization with 2 to 4 lb/1000 ft2 per year should be adequate to maintain acceptable vines and groundcovers grown in the landscape in west-central Florida.

Open access

Heather Kalaman, Sandra B. Wilson, Rachel E. Mallinger, Gary W. Knox, Taehoon Kim, Kevin Begcy, and Edzard van Santen

Consumer demand for novel, visually attractive ornamentals has often overshadowed the functional value plants may provide for flower-visiting insects. As native and nonnative species are hybridized for form, color, flowering, and disease resistance, it is important to assess whether some of these alterations influence plant nutrient quality for foraging insect pollinators. A study was conducted to ascertain the resource value of ornamental cultivars compared with their native congeners. The nectar volume and pollen quantity, viability, and protein content of 10 species of popular herbaceous flowering plants, commonly advertised as pollinator-friendly, were evaluated in northcentral Florida. Each genus encompassed a native and nonnative species, apart from pentas. Native species included blanket flower (Gaillardia pulchella), lanceleaf coreopsis (Coreopsis lanceolata), pineland lantana (Lantana depressa), and scarlet sage (Salvia coccinea). Nonnative species included Barbican™ yellow-red ring blanket flower (Gaillardia aristata ‘Gaiz005’), Bloomify™ rose lantana (Lantana camara ‘UF-1011-2’), mysty salvia (Salvia longispicata × farinacea ‘Balsalmysty’), Lucky Star® dark red pentas (Pentas lanceolata ‘PAS1231189’), ruby glow pentas (Pentas lanceolata ‘Ruby glow’) and UpTick™ Gold & Bronze coreopsis (Coreopsis × ‘Baluptgonz’). Floral rewards differed significantly across species. The native scarlet sage exhibited the largest nectar volume per flower in the summer (2.13 ± 0.17 µL), followed by the nonnative mysty salvia (1.26 ± 0.17 µL). In the fall, ruby glow pentas exhibited the largest nectar volume per flower (1.09 ± 0.17 µL) compared with all other ornamentals. The composite flowers of the native and nonnative blanket flower and coreopsis species had the lowest nectar volume per flower regardless of sampling date. Likewise, ruby glow pentas displayed the highest quantity of pollen grains (96.29 ± 0.12) per sample, followed by Lucky star pentas (52.33 ± 0.12), and Barbican blanket flower (50.98 ± 0.12). Pollen viability was similarly high (92% to 98%) among all species, apart from Bloomify rose lantana (20%) and pineland lantana (48%). Pollen protein content was highest in Uptick coreopsis (11.378 ± 1.860 μg/mg dry weight) and Lucky star pentas (10.656 ± 3.726 μg/mg dry weight), followed by lanceleaf coreopsis (7.918 ± 1.793 μg/mg dry weight). These results largely showed that the nonnative ornamentals selected provided resource-rich floral rewards, comparable to native congeners. Still, care should be taken in making similar assessments of other modern floral types.

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Anthony LeBude, Amy Fulcher, Jean-Jacque Dubois, S. Kris Braman, Matthew Chappell, J.-H (J.C.) Chong, Jeffrey Derr, Nicole Gauthier, Frank Hale, William Klingeman, Gary Knox, Joseph Neal, and Alan Windham

Three, 2-day hands-on experiential learning workshops were presented in three southeastern United States cities in June 2014, by the Southern Nursery Integrated Pest Management (SNIPM) working group. Attendees were provided 4 hours of instruction including hands-on demonstrations in horticultural management, arthropods, plant diseases, and weeds. Participants completed initial surveys for gains in knowledge, skills, and abilities as well as their intentions to adopt various integrated pest management (IPM) practices after the workshop. After 3 years, participants were again surveyed to determine practice adoption. Respondents changed their IPM practice behavior because of attending the workshops. Those returning the survey set aside more time to scout deliberately for pests, plant diseases, and weeds; used a standardized sampling plan when scouting; and adopted more sanitation practices to prevent plant disease. Fewer horticultural management practices were adopted than respondents originally intended. Future emphasis should be placed on using monitoring techniques to estimate pest emergence, for example, traps and pheromone lures, as well as plant phenology and record keeping. However, more work is needed to highlight both the immediate and long-term economic benefits of IPM practice adoption in southeastern U.S. nursery production.

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Amy Fulcher, Anthony LeBude, Sarah A. White, Matthew R. Chappell, S. Christopher Marble, J.-H (J.C.) Chong, Winston Dunwell, Frank Hale, William Klingeman, Gary Knox, Jeffrey Derr, S. Kris Braman, Nicole Ward Gauthier, Adam Dale, Francesca Peduto Hand, Jean Williams-Woodward, and Steve Frank

Extension and research professionals in the southeastern United States formed the Southern Nursery Integrated Pest Management working group (SNIPM) to foster collaboration and leverage resources, thereby enhancing extension programming, increasing opportunity, and expanding the delivery of specialized expertise to nursery crop growers across a region. Building a productive and lasting working group requires attracting a group of research and extension faculty with complementary expertise, listening to stakeholders, and translating stakeholder needs into grant priorities to help solve problems, all hallmarks of effective teamwork principles. SNIPM has now grown to include 10 U.S. states and 11 institutions and has been awarded seven grants totaling $190,994 since 2009. A striking benefit of working group membership was observed over time: synergy. Greater awareness of individual expertise among SNIPM members, each of whom were focused on different aspects of the nursery production system stimulated multistate extension publications, electronic books (eBooks), mobile device applications (apps), popular press articles, and spin-off research projects when separate foci were combined and directed toward complex challenges. Deliverables achieved from this faculty collaboration include nine peer-reviewed publications, four manuals and books and 23 book chapters, and a combined total of 11 abstracts, conference proceedings and extension publications. To date, the return on investment for SNIPM is one deliverable produced to every $2265.89 in grant funding. SNIPM has also been honored with multiple American Society for Horticultural Science publication awards as well as the Southern Region Integrated Pest Management Center Bright Idea Award for the quality and originality of their project outputs. Continuing to work together toward common goals that bridge technology and serve the nursery industry while supporting each individual member’s program will be crucial to the long-term success of this working group.