Search

Native and non-native bees are important pollinators of both food and ornamental crops. However, bee populations across the world have declined, mainly through loss of habitat. Careful selection of landscape plants in urban areas can help mitigate habitat loss and create new habitat for pollinators. Ten mature genotypes of Vitex, comprising V. agnus-castus L., V. negundo L., and a hybrid between V. agnus-castus x V. rotundifolia L. f., were evaluated during June and July 2016 to assess their attractiveness to pollinators. Pollinator counts were taken two times daily, at 9:00 a.m. and 11:00 a.m., twice weekly for three weeks. Pollinators were also captured from the Vitex plants for identification. Insects captured from Vitex plants were identified to genus and bumblebees [Bombus spp. (Latreille, 1802)] were further identified to species. Bumblebees and honeybees [Apis mellifera (Linnaeus, 1758)] were more numerous on Vitex plants than carpenter bees. V. agnus-castus plants attracted more bumblebees than honeybees. V. negundo and the V. agnus-castus x V. rotundifolia hybrid attracted more pollinators over the course of the study than V. agnus-castus. Our study shows that Vitex plants can be a good resource to support pollinators in an urban landscape. Index words: urban landscape, bumblebees, honeybees; Vitex agnus-castus, Vitex negundo, Vitex rotundifolia. Species used in study: Vitex agnus-castus L.; Vitex negundo L.; Vitex rotundifolia L.

Native grasses are increasingly used in the landscape. Little bluestem (Schizachyrium scoparium L.), a perennial bunchgrass native to most of the United States, has ornamental traits, such as variation in leaf color, differences in growth morphology, and attractive seed heads. Traditionally, cultivars of little bluestem are propagated by division, which limits the production of new plants. Our objective in this study was to develop an improved micropropagation protocol for little bluestem that would produce true-to-type plants. In 2016, we cultured immature inflorescences of eight genotypes of little bluestem on Murashige and Skoog (MS) medium with four combinations of kinetin (1.0 or 2.0 mg·L−1) and 2,4-D (0.5 or 1.0 mg·L−1) under three levels of light (dark, semilight, full light) to initiate callus. Cultures were evaluated 30 days after initiation and those that had initiated callus were subcultured. Media for subculturing and rooting contained either 0.1 mg·L−1 or no 1-Naphthaleneacetic acid (NAA). Light level had no effect on callus initiation. Initiation media with 1.0 mg·L−1 kinetin and either level of 2,4-D induced callus at almost twice the rate of media with 2.0 mg·L−1 kinetin, and cultures initiated on those media also produced almost twice the number of rooted plants over all genotypes. Genotype affected the number of rooted plants produced. The addition of NAA to medium for subculturing and rooting did not increase the number of rooted plants. In 2017, we cultured immature inflorescences of four genotypes of little bluestem on MS medium with 0.5 mg·L−1 2,4-D and either 1.0 mg·L−1 kinetin or 6-benzylaminopurine (BAP) under full light. Cultures were evaluated 30 days after initiation. Cultures that had initiated callus were subcultured onto MS medium with the same growth regulators as the initiation medium but without 2,4-D. Cultures were cycled between subculture medium with growth regulator and subculture medium with no additional growth regulator until rooted. Cultures initiated and subcultured on medium with BAP initiated two to three times more callus than those on kinetin and produced twice as many rooted plants. Our recommendation for rapid micropropagation of little bluestem is to initiate cultures on MS medium with 1.0 mg·L−1 BAP and 0.5 mg·L−1 2,4-D. After callus initiation, cultures should be subcultured to medium with BAP but no 2,4-D, alternating with medium with no additional growth regulators, until rooted.

Interspecific and intergeneric crosses were performed between species in the genera Baptisia and Thermopsis with the goal of creating hybrids with the best qualities of both parents. Baptisia australis (L.) R. Br. was used as both the male and female parent in intergeneric crosses. Thermopsis chinensis Benth. ex S. Moore, T. lupinoides (L.) Link, and T. villosa Fernald & B.G. Schub. were used as male and female parents in both interspecific and intergeneric crosses. Pollen was collected from B. alba (L.) Vent., B. bracteata Muhl. ex Elliott, and B. lanceolata (Walt.) Ell. and used to make interspecific and intergeneric crosses. Putative hybrids were obtained from both interspecific and intergeneric crosses. Interspecific crosses produced a higher percentage of pollinations resulting in seed set and the number of seeds per pollination than intergeneric crosses. Morphological differences between parent species and progeny were evident in putative hybrids resulting from intergeneric crosses between T. villosa and B. australis and T. villosa and B. alba. Most putative hybrids bloomed during the second year after germination. Because seedlings could be obtained from both interspecific and intergeneric crosses, hybrids within and between the genera Baptisia and Thermopsis are feasible. The Fabaceae family contains 670–750 genera and 18,000–19,000 species. Baptisia (commonly called false or wild indigo) and Thermopsis (commonly named false lupine) of the Fabaceae belong to the tribe Thermopsidae, which comprises 46 species in six genera. All species in Thermopsis and Baptisia are herbaceous; they are the only two genera in Thermopsidae that do not have woody species. Thermopsis contains 23 species and has a wide-spread distribution with species endemic to Asia and much of temperate North America. Although Thermopsis is considered to have originated in central Asia, T. chinensis Benth. ex S. Moore and T. fabacea (Pallas) Candole are thought to have originated in North America and migrated over the Bering Land Strait to Asia. Three Thermopsis species, T. fraxinifolia Nutt. ex M.A. Curtis, T. mollis (Michx.) M.A. Curtis ex A. Gray, and T. villosa Fernald & B.G. Schub., are native to the southeastern United States. Baptisia contains 15–17 species that are endemic to the southeastern and midwestern United States.

Four species of Dissotis and three species of Tibouchina, two genera of the Melastomataceae family, were crossed in an attempt to create interspecific and intergeneric hybrids. Intergeneric crosses set seed at a rate of 18.1% and interspecific crosses had a 32.3% rate of seed set. Germination was extremely poor, with only four crosses having germinated seed. Crosses produced 31 seedlings. Three of the seedlings were from intergeneric crosses between Dissotis canescens and Tibouchina lepidota. Interspecific crosses produced 25 seedlings from crosses between Dissotis princeps and Dissotis rotundifolia and three seedlings from crosses between D. canescens and D. princeps. The prognosis for conventional breeding for species in Dissotis and Tibouchina is poor due to low seed set, poor germination, and slow growth of progeny.

Dissotis rotundifolia (Sm.) Triana and Tibouchina fothergillae ×pilosa are members of the Melastomataceae family with high ornamental potential. The growth habits of these species are not ideal for nursery production or shipping. D. rotundifolia grows rapidly and needs frequent pruning. T. fothergillae ×pilosa has an open growth habit and could benefit from a more compact form. The effect of the plant growth regulator (PGR) paclobutrazol on D. rotundifolia and T. fothergillae ×pilosa was assessed to determine whether it could produce plants with a more compact growth habit. Paclobutrazol was applied as a drench and a spray. Drench application was more effective in reducing the growth of both species. Spray application was effective in reducing the growth of D. rotundifolia but was not effective on T. fothergillae ×pilosa. Neither drench nor spray application delayed or reduced flowering in D. rotundifolia. T. fothergillae ×pilosa did not flower during the study. For both D. rotundifolia and T. fothergillae ×pilosa, neither drench nor spray application had an effect on root dry weight. Low-to-medium dosages were effective at controlling plant growth in D. rotundifolia and T. fothergillae ×pilosa without adverse effects on plants. Drench treatments have more persistent effects on plant growth than spray treatments.

Lantana camara L., a popular nursery and landscape plant, is categorized as an invasive species in Florida, because it produces viable pollen and cross-pollinates with the native species Lantana depressa Small. The invasive potential of L. camara is a challenging issue for the nursery and landscape industry, so sterile non-invasive cultivars are needed to replace fertile invasive ones. This study aimed to determine the ploidy level and male fertility of both commercial L. camara cultivars and breeding lines to identify male-sterile cultivars and assess the effectiveness of sterile triploid production in L. camara. A polyploid series was identified among 32 L. camara cultivars and breeding lines. Male fertility, based on pollen stainability, varied widely among the cultivars/breeding lines. Ploidy level was the most important factor determining L. camara pollen stainability/male sterility. On average, diploids exhibited the highest pollen stainability (64.6%) followed by tetraploids (45.1%), pentaploids (34.6%), and hexaploids (18.0%). Triploids showed the lowest pollen stainability (9.3%), suggesting that generating triploids would be an effective genetic approach to producing sterile L. camara and reducing its pollen-mediated invasiveness. Pollen stainability of triploid cultivars, Balandpawn (LandmarkTM Pink Dawn PP15,516), Lemon Drop, Miss Huff, New Gold, New Red Lantana, Red Butler, Red Spread Lantana, Samson Lantana, and Sunset Lantana was consistently below 10%. A number of triploid cultivars had pollen stainability approaching 20% to 30%, indicating a necessity for careful examination and screening of newly produced triploids to ensure high sterility in selected triploids. Pollen stainability variation was observed within ploidy levels, implying the existence of other genetic and environmental factors that influence the pollen stainability/male fertility of L. camara. Results from this study suggest that there is excellent potential to develop genetically sterile cultivars in L. camara for the U.S. nursery and landscape industry.

Interspecific and intergeneric crosses were performed between species in the genera Baptisia and Thermopsis in an attempt to create hybrids with the best qualities of both parents. Interspecific crosses produced a higher percentage of fertile crosses and number of seeds per fertile cross than intergeneric crosses. Germination rate was not different between interspecific and intergeneric crosses. When comparing species to determine the best female parents, we found no difference between female parents for percentage of fertile crosses or germination rate. However, Thermopsis female parents produced a higher number of seed per cross than Baptisia female parents. When comparing species to determine the best male parents, crosses with Thermopsis male parents produced more seed per cross than those with Baptisia male parents, but were not different for percentage of fertile crosses or germination rate. Since seedlings could be obtained from both interspecific and intergeneric crosses, production of a Baptisia-Thermopsis hybrid is feasible. Steps to increase the percentage of fertile crosses and number of seedlings include new species as parents, use of bridge parents, embryo rescue, and selection of the male and female parents that produced the most fertile crosses for further breeding efforts.

New ornamental cultivars must display horticultural superiority when grown in containers or in the field. The objectives of this study were to determine whether container or field is most appropriate for initial selection of ornamental traits in a Vitex breeding program by determining whether quantitative traits of breeding interest were expressed similarly in the two environments and by determining trait correlations in each environment. Segregating populations of Vitex and their parents were cloned and grown in containers and in the field. Ornamentally significant traits evaluated included first flower date, last flower date, flowering period, total weeks of flowering, inflorescence number, inflorescence length, flower rating, plant height, plant width, and Cercospora leaf spot resistance. Overall, field-grown plants were taller and wider than plants grown in containers. Field-grown plants also had a later first flowering date, longer flowering period, greater total weeks flowering, longer inflorescence length, larger inflorescence number, and more flowers on the inflorescence. Significant genotype × environment interactions were found for height and width measurements taken 19 and 33 weeks after planting, first flower date, total weeks in flower, inflorescence number, flower rating, and Cercospora rating. Most trait correlations were either non-significant or so low so that selection of these traits would be independent of other traits. High correlations were present in both environments between height measurements taken at 19 weeks and 33 weeks after planting. High correlation in the field and moderate correlation in containers were found between width measurements taken 19 and 33 weeks after planting. Correlation was high between flowering period and first flower date in both the field and container. Correlation between last flower date and flowering period was high in containers and moderate in the field. High correlation was present in both environments between flowering period and total weeks of flowering. Containers were determined to be best for initial selection for most traits having significant genotype × environment effects.

The genetic diversity among H. macrophylla (Thunberg) Seringe taxa is limited as a result of the restricted native distribution and multiple breeding programs that used the same taxa and targeted similar breeding goals. This study assessed the compatibility of interspecific crosses between Hydrangea macrophylla and H. angustipetala Hayata as a source of genetic diversity. Two lacecap cultivars of H. macrophylla, ‘Lady in Red’ and Midnight Duchess® (‘HYMMAD II’), were compatible with H. angustipetala. Hybridity of progeny was confirmed by simple sequence repeat markers and morphological comparisons. Some hybrids had red- or purple-pigmented stems, which are characteristic of ‘Lady in Red’ or Midnight Duchess®, respectively. All hybrids had white lacecap inflorescences. Some of the hybrid flowers were fragrant. Winter leaf retention of the hybrids ranged from deciduous to semievergreen. Male fertility of progeny was evaluated by fluorescein diacetate staining of pollen. ‘Lady in Red’, Midnight Duchess®, and H. angustipetala had 62%, 58%, and 79% stainable pollen, respectively, whereas the ‘Lady in Red’ × H. angustipetala and Midnight Duchess® × H. angustipetala hybrids had means of 48% and 47% stainable pollen, respectively. Selected progeny were used to develop F2 and BC1 populations. The interspecific hybrids produced in this study were attractive, fertile plants that are being used in further breeding to develop new cultivars.

Despite the ecologic and economic importance of native deciduous azaleas (Rhododendron L. section Pentanthera G. Don), our understanding of interspecific variation of North American deciduous azalea species comes principally from morphologic studies. Furthermore, little is known concerning intraspecific or interpopulation genetic variation. With ever-increasing loss and fragmentation of native azalea habitat in the eastern United States due to anthropogenic activity, it is imperative that an understanding of natural genetic variation among and within species and populations is acquired. The present study addresses questions of genetic diversity through the use of amplified fragment length polymorphism (AFLP) analysis. Twenty-five populations of seven species of native azalea were analyzed using three primer pairs that amplified a total of 417 bands. Based on analysis of molecular variance (AMOVA) and estimates of Nei's coefficients of gene diversity (H S, H T, and G ST), the majority of variation found in deciduous azalea occurs within populations. Variation both among species and among population was low, likely the effect of common ancestry as well as frequent introgression among members (and populations) of section Pentanthera. The latter was evident in four populations of R. prunifolium (Small) Millais and R. canescens (Michaux) Sweet that were highly related to R. austrinum (Small) Rehder and R. viscosum (L.) Torrey, respectively. Despite these outliers, most populations were grouped into species based on Nei's unbiased genetic distances viewed as an unweighted pair group method with arithmetic mean (UPGMA) phenogram. The significance of these results is discussed in relation to breeding in section Pentanthera.

North of USDA hardiness zone 7B, abelia suffers from freeze damage. Cultural factors may impact abelia's level of cold hardiness. To determine whether mid-season pruning affects the level of freeze damage, six abelia genotypes were tested in Griffin, GA. Plants were established in replicated field plots in 2001 and on July 3–4, 2003, half the individuals of each genotype were severely pruned. Laboratory freeze tests were conducted monthly on pruned and unpruned plants of each genotype from October 2003 to April 2004. Over the winter, all genotypes with exception of ‘Canyon Creek’ were significantly more cold tolerant in unpruned compared to pruned treatments. Analysis of each month independently revealed a significant difference among genotype-pruning treatment combinations from December 2003 to February 2004. Results for October and November 2003 and March and April 2004 were not significant due to an absence of cold hardiness. These results indicate that mid-season pruning of abelia may significantly reduce cold hardiness and lead to serious stem dieback in pruned plants.

Azaleas (Ericales: Ericaceae: Rhododendron L.) are a staple plant in many landscapes of the United States and are largely resistant to predation by insects, with the exception of azalea lace bug [ALB (Heteroptera: Tingidae: Stephanitis pyrioides)]. Within deciduous azalea (Rhododendron: section Pentanthera G. Don) varying levels of resistance to ALB are observed with a continuous distribution from susceptible to highly resistant. In this study, epicuticular leaf wax from two ALB-resistant [R. canescens Michaux and R. periclymenoides (Michaux) Shinners] and two ALB-susceptible (`Buttercup' and `My Mary') deciduous azalea genotypes was extracted and re-applied to fresh azalea foliage. Leaf wax extracted from ALB-resistant genotypes and applied to ALB-susceptible genotypes conferred a high level of resistance to both ALB feeding and oviposition in the treated ALB-susceptible genotypes. Conversely, leaf wax extracted from ALB-susceptible genotypes and applied to ALB-resistant genotypes conferred susceptibility to the treated ALB-resistant genotypes. However, the effect was much less substantial than the effect of resistant wax extracts on susceptible genotypes and confined to ALB oviposition. When applied to the same genotype from which the extract was collected, leaf wax extract from ALB-susceptible genotypes had no effect on susceptibility, whereas resistant wax extract had a moderate effect on ALB oviposition rate. The results indicate that leaf wax serves as a primary mechanism of resistance of deciduous azalea to ALB.

Seed germination within Abelia R. Br. spp. has been described as slow and inconsistent. An experiment was conducted with seeds of Abelia ×grandiflom (André) Rehd. (glossy abelia) to test procedures to increase germination percentage, uniformity and rate. The effect of pericarp removal was examined on seeds with no additional treatment, and on seeds that were stratified (moist-prechilled) for 60 days at 4C (39F) or immersed in 100 mg/liter gibberellic acid for 24 hr. Treatments were replicated five times with 15 seeds per replication. Seeds were sown on sphagnum peat, and germinated under mist in a greenhouse. Weekly germination counts were recorded for 8 weeks. Seeds with intact pericarps germinated at a significantly higher percentage than those without pericarps. Stratified seeds germinated in fewer days than the other treatments. The combination of stratified seeds with intact pericarps gave the best overall response, with final germination of 62% and a reduction in germination time to 14 days (to reach 90% final germination) as compared to 35 days for untreated seeds.

Inter specific hybridization among species of Abelia offers the potential for new cultivars. Seeds from inter specific hybridization between A. × grandiflora ‘Francis Mason’ × A. schumannii failed to germinate, and ovule culture was employed. Ovules were dissected from the achenes 4, 5, and 6 weeks after pollination and cultured on either Woody Plant Medium (WPM) or Linsmaier and Skoog (LS) Medium containing 0, 9.8, or 39.2 μM 2iP. All media contained coconut water (5% v/v), sucrose(30 g/l), agar (8 g/l), and MS vitamins (1 mg/l). Embryos recovered, spontaneous embryo germination, root formation, and plant survival were recorded. Number of weeks following pollination significantly affected all parameters examined, with ovules harvested 5 weeks after pollination producing the best results. Plant survival was greatest for embryos cultured on Woody Plant Medium with 0 μM 2iP. Eight-five percent of the cultured ovules produced embryos that rooted and 65% survived the hardening off process when ovules were cultured 5 weeks after pollination on WPM containing no growth regulator.

Twelve taxa of Abelia were evaluated using laboratory procedures to determine maximum stem and leaf hardiness and to evaluate timing of acclimation and deacclimation over a two-year period. Among the 12 Abelia taxa evaluated, ‘John Creech’ was among the hardiest taxa for both stems and leaves on the majority of test dates. Stems and leaves of ‘John Creech’ survived to at least −26C (−15F) and −21C (−6F), respectively, in January 2001. ‘Edward Goucher’ and ‘Confetti’ had the least hardy stems and leaves, respectively. Stems of ‘Edward Goucher’ survived to at least −16C (3F) in January 2000, and ‘Confetti’ leaves survived to only −14C (7F) in December 2000. Abelia × grandiflora consistently ranked among the first to attain cold hardiness in the fall and among the last to lose cold hardiness in the spring in both test seasons. Stems were equal in hardiness or hardier than leaves on the majority of test dates in both test seasons. Laboratory results were consistent with field observations, but often differed from published hardiness ratings. Differences in lowest survival temperatures and attainment and retention of cold hardiness closely followed temperature fluctuations just prior to sampling dates.

Twelve taxa of deciduous azalea were evaluated using laboratory procedures to determine hardiness of stems and flower buds. Rhododendron atlanticum, ‘My Mary’, ‘Nacoochee’, and ‘TNLV1’ exhibited the greatest stem cold hardiness, surviving to at least −29C ± 1 (−20F ± 2) in February 1996. Rhododendron oblongifolium exhibited the least stem cold hardiness, surviving to only −11C ± 1 (10F ± 2). All results were consistent with previous field studies. Except for R. viscosum and R. serrulatum, lowest survival temperatures for stems were analogous to reports available in the literature. Rhododendron viscosum and ‘My Mary’ had the lowest survival temperature recorded for flower buds, −23C ± 1 (−9F ± 2), in February 1998 and February 1999, respectively, though not significantly different than most other taxa examined. Lowest survival temperatures for flower buds varied from published accounts, with buds in the present study being less hardy than previously reported. Differences from published reports in the lowest survival temperatures of stems and flower buds are attributed to provenance, temperature fluctuations, cultural effects on the plants, and differences among freeze test protocols.

Genetic relationships among specimens of the 15 currently recognized species in Rhododendron L. section Pentanthera G. Don were derived from sequence comparisons of the internal transcribed spacer (ITS) region. Sequences of the entire ITS region including ITS1, ITS2, and the 5.8S subunit were generated by direct sequencing of polymerase chain reaction (PCR) amplified fragments. Rhododendron vaseyi A. Gray, Rhododendron section Rhodora (L.) G. Don was used as an outgroup. Aligned sequences of the 16 taxa resulted in 688 characters. The region contained 38 variable sites and eight phylogenetically informative characters. A bootstrap analysis was performed and a dendrogram was constructed with MEGA. Divergence values among the taxa were extremely low ranging from 0.00 to 3.51%, providing support to traditional views of section Pentanthera as a group of very closely related species.

Epicuticular lipids were extracted from the foliage of six deciduous and one evergreen azalea genotypes (Rhododendron sp.) and identified by gas chromatography-mass spectrometry. The relationship of leaf-surface lipid composition with measures of resistance to azalea lace bug, Stephanitis pyrioides Scott, was evaluated. Each genotype had a distinct epicuticular lipid composition. The major surface lipid components from all test taxa were n-alkanes and triterpenoids. In the most resistant genotypes [R. canescens Michaux and R. periclymenoides (Michaux) Shinners] ursolic acid, n-hentriacontane, and n-nonacosane were the most abundant epicuticular lipids. The lipids present in largest proportion among all susceptible deciduous genotypes tested were α-amyrin, β-amyrin, and n-nonacosane. The proportions of the lipid components from the same plant of each genotype varied between spring and fall samples. Among classes of lipids, n-alkanes, n-1-alkanols, and triterpenoids had significant correlations with azalea lace bug behavior on host plants. Among individual components, heptadecanoic acid, n-hentriacontane, oleanolic acid, ursolic acid and one unknown compound (with major mass spectra 73/179/192/284/311) were significantly negatively correlated with host plant susceptibility to azalea lace bug, as measured by oviposition, leaf area damaged, egg and nymphal development, and nymphal survivorship. Triacontanol, α-amyrin, β-amyrin, and three unknowns were significantly positively correlated with host plant susceptibility. Acceptance or rejection by azalea lace bug to a particular plant may be mediated by a balance of positively and negatively interpreted sensory signals evoked by plant chemicals. This study indicated that the high levels of resistance observed in R. canescens and R. periclymenoides may be due to the lesser amount or the absence of attractants and stimulants for feeding or oviposition.

The susceptibility of seventeen deciduous species or cultivars and one evergreen cultivar of azalea (Rhododendron spp.) to azalea lace bug (Stephanitis pyrioides Scott) was evaluated in field and laboratory experiments. Rhododendron canescens Michx. and R. periclymenoides (Michx.) Shinners were the most resistant species, followed by R. prunifolium (Small) Millais. Ratings were based on oviposition rate, percentage emergence from the egg, feeding damage, and nymphal growth rate. The most susceptible genotypes were TNLV1, R. oblongifolium (Small) Millais, R. alabamense Rehder, R. serrulatum (Small) Millais, R. viscosum (L.) Torr., `Buttercup', and `My Mary'. Leaf water content and leaf pubescence were significantly different among taxa. However, leaf water content was not significantly correlated with azalea lace bug performance, and insufficient evidence was available to conclude that leaf pubescence was involved in azalea lace bug resistance.

Questionnaires on pesticide use and other aspects of integrated pest management (IPM) were mailed to 1678 lawn care and landscape maintenance firms in the 20 county metropolitan Atlanta area. The survey return rate adjusted for nonapplicable addresses and undeliverable mailings was 25.4%, yielding a total of 350 usable surveys. Responding lawn care and landscape maintenance professionals purchased a total active ingredient of 250,527 lb (93,447 kg) of herbicide, 35,416 lb (13,210 kg) of insecticide and 10,367 lb (3,867 kg) of fungicide during 1993. Most insecticides and fungicides were applied during June, July, and August. About one-third of herbicides were applied during March to May, one-third during June to August, and one-third during September to February. Key pests and plants were identified by survey respondents. Opportunities and impediments to implementation of IPM in the landscape as reported by respondents are discussed.

A survey indicated that the landscape maintenance and lawn care industry of the Atlanta metro area was localized in densely populated counties with a high concentration of commercial activity and residential housing. A relatively young age and limited size of most of the firms suggested a lack of barriers to entering the industry, which was supported by gross sales and equipment owned by surveyed companies. Most firms generated no more than $100,000 in sales in 1993 and owned equipment valued at less than $25,000. Most residential accounts were under 10 acres.

The cost of publishing this paper was defrayed in part by the payment of page charges. Under postal regulations, this paper therefore must be hereby marked advertisement solely to indicate this fact. Additional index words. runoff, surface water contamination, best management practices Summary. Optimizing growing conditions and, thereby, plant growth reduces the susceptibility of plants to many disease and insect pest problems. Educating lawn or landscape management professionals and homeowners about plant health management reduces the need for chemical intervention. Pesticides combined with N and P fertilizers contribute to water pollution problems in urban areas; thus, it is important to manage the amount, timing, and placement of chemicals and fertilizers. To educate consumers applying pesticides and fertilizers in residential gardens, we must educate the sales representatives and others who interact most closely with consumers. Evidence suggests that knowledge about the effects of chemicals is limited and that warning labels are not read or are ignored. Integrated pest management (IPM) offers alternatives to conventional chemical treatments, but such methods are not used commonly because of their relatively high cost and their uncertain impact on pests. Pest detection methods and using pest-resistant plants in landscapes are simple and, in many cases, readily available approaches to reducing the dependence on chemical use. Research on effective, low-cost IPM methods is essential if chemical use in landscape management is to decrease. Current impediments to reducing the pollution potential of chemicals used in the landscape include the limited number of easily implemented, reliable, and cost-effective alternative pest control methods; underfunding of research on development of alternative pest control measures; limited knowledge of commercial operators, chemical and nursery sales representatives, landscape architects, and the general public concerning available alternatives; reluctance of the nursery industry to produce, and of the landscape architects to specify the use of, pest-resistant plant materials; lack of economic or regulatory incentive for professionals to implement alternatives; inadequate funding for education on the benefits of decreased chemical use; and the necessity of changing consumer definition of unacceptable plant damage. We need to teach homeowners and professionals how to manage irrigation to optimize plant growth; use sound IPM practices for reducing disease, weed, and insect problems; and minimize pollution hazards from fertilizers and pesticides.

HortTechnology ● April–June 1996 6(2) Summary. Pesticides have been the primary method of pest control for years, and growers depend on them to control insect and disease-causing pests effectively and economically. However, opportunities for reducing the potential pollution arising from the use of pesticides and fertilizers in environmental horticulture are excellent. Greenhouse, nursery, and sod producers are using many of the scouting and cultural practices recommended for reducing the outbreak potential and severity of disease and insect problems. Growers are receptive to alternatives to conventional pesticides, and many already use biorational insecticides. Future research should focus on increasing the effectiveness and availability of these alternatives. Optimizing growing conditions, and thereby plant health, reduces the susceptibility of plants to many disease and insect pest problems. Impediments to reducing the use of conventional pesticides and fertilizers in the environmental horticulture industry include 1) lack of easily implemented, reliable, and costeffective alternative pest control methods; 2) inadequate funding for research to develop alternatives; 3) lack of sufficient educational or resource information for users on the availability of alternatives; 4) insufficient funding for educating users on implementing alternatives; 5) lack of economic or regulatory incentive for growers to implement alternatives; and 6) limited consumer acceptance of aesthetic damage to plants. Research and broadly defined educational efforts will help alleviate these impediments to reducing potential pollution by the environmental horticulture industry.

An apparatus was developed that featured programmable application of liquid medium to plant cultures for micropropagation. Computer control capabilities included liquid medium introduction and medium depth within four culture vessels, medium application and removal on an assigned schedule, schedule adjustment during a culture period and medium replacement. The medium level was controlled using an accurate custom level-sensing technique consisting of thermistors and float switches. Seven-liter polycarbonate containers were modified and used as the culture vessels. Maintaining sterility was a key constraint in the development of the plant tissue culture apparatus.

A micropropagation system was developed to test concepts for automation and microenvironment alteration. Amelanchier x grandiflora Rehd. ‘Princess Diana’ (serviceberry) shoot cultures were grown in seven-liter polycarbonate containers. Through computer control, the apparatus intermittently applied culture medium to the plant material according to a selected schedule. Shoot growth in the programmable system was compared with four micropropagation treatments: gelled and liquid medium in baby food jars and gelled and non-cycling liquid medium in a seven-liter vessel. Plants cultured in continuous contact with liquid medium became increasingly vitrified. Significantly greater shoot number, shoot length, shoot weight, and culture weight occurred in the programmable system than in jars with gelled medium. The combination of liquid medium, 7-liter vessel, and intermittent contact with medium caused a significantly higher proliferation rate than any combination of jar/vessel and gelled/liquid medium tested.

A comparison of semi-solid vs. liquid embryo proliferation media was made using two Gossypium hirsutum L. genotypes (Coker 312 and T25) and two callus initiation media. Sections of petioles from mature, flowering plants were cultured on two modified Murashige and Skoog media. Medium 1 included 4.0 mg l-1 NAA and 1.0 mg l-1 kinetin; medium 2 contained 0.1 mg l-1 2,4-D and 0.1 mg l-1 kinetin. After six weeks, callus was removed from each explant and divided in half. One callus portion was placed in liquid proliferation medium and the other on semi-solid (0.2% Gelrite) proliferation medium. Composition of proliferation medium was identical to that of initiation medium, except no growth regulators were added. Embryos were counted after eight weeks. The percentage of explants forming callus was influenced by genotype/initiation medium combination. Analysis of variance procedures revealed significant variability for callus initiation media, proliferation media (semi-solid or liquid), and an initiation medium x genotype interaction. Paired t-tests indicated that more embryos were produced in liquid proliferation medium (227.3 embryos/culture) than on semi-solid proliferation medium (134.6 embryos/culture).

Three commercial varieties (Acala SJ-5, Coker 312 and Paymaster 303) and three exotic accessions (T1, T25 and T169) of cotton (Gossypium hirsutum L.) were tested for ability to undergo somatic embryogenesis. Sections of split petiole were cultured on 3 media and evaluated for embryogenesis after 180 days. Embryogenic T25 and Coker 312 plants were selected and crossed in a diallel with non-embryogenic Acala SJ-5, Paymaster 303, T1 and T169 plants. F1, F2 and BC1 populations were generated and tested for embryogenesis on a medium of MS salts and vitamins (1962) plus (per liter) 4.0 mg NAA, 1.0 mg Kn, 30 g glucose, 100 mg myo-inositol, 2.0 g Gelrite and 0.75 g MgCl2. Segregation for both occurrence and magnitude of embryogenesis was observed, suggesting the action of more than one gene.

Dwarf pampas grass (Cortaderia selloana Schult. ‘Pumila’) plantlets produced in vitro were subjected to one of seven fertilization treatments during acclimatization to greenhouse conditions. Though all plantlets survived acclimatization, level of fertilizer significantly affected growth rate. Increase in fresh weight, leaf number and tillering during the first 6 weeks of acclimatization was greater when Osmocote micro-fertilizer at 2 kg/m3 (oz/ft3) was incorporated into the growing mix (Pro-Gro 200 with starter nutrients) as compared to 4 kg/m3 (oz/ft3) of Osmocote or addition of liquid fertilizer. The slowest growth was obtained from plants growing without Osmocote or liquid fertilizer. Once adapted to the greenhouse, plants fertilized with 400 mg/1 (ppm) N from 17N-4P-11K (17-9-13) soluble fertilizer twice per week had the most rapid growth.

Immature leaf laminae and petioles of `Regale' and `Fry' muscadine grapes (Vitis rotundifolia Michx.) were cultured on Nitsch and Nitsch (NN) medium supplemented with 9.0 μm 2,4-D and 4.4 μm BA, and gelled with agar. Callus and original explant tissues were transferred to NN medium containing 10.7 μm NAA and 0.9 μm BA to proliferate embryogenic callus, which, when transferred to NN medium without growth regulators, yielded globular embryos. The embryos matured and germinated after being subcultured to fresh medium without growth regulators. Somatic embryogenesis incidence was greater from petioles than laminae: 90% of `Regale' and 50% of `Fry' petioles formed embryos, compared with 14% and 2% of laminae, respectively. Culturing germinated somatic embryos on NN medium with 1 μm BA enhanced shoot growth. Regenerated plants flowered and appeared morphologically normal. Chemical names used: N-(phenylmethyl)- 1H -purin-6-amine (BA); 2,4-dichlorophenoxyacetic acid (2,4-D); α- naphthaleneacetic acid (NAA).

Firm characteristics and managers' attitudes and opinions about pesticide safety were used to classify lawn care and landscape management firms into four categories and compare them using the logit procedure. Survey data obtained from 223 firms was used in the empirical investigation of the adoption of the IPM techniques. Results showed the need for continued transfer of new technology to independently owned firms, multidisciplinary assessment of IPM methods before their transfer to ascertain the economic viability of proposed methods, public investment in programs training workers in knowledge-based pesticide applications, possible assistance in obtaining capital, and investment in consumer education.

Abelia ×grandiflora is a hardy shrub in the landscape, surviving heat and drought with few pest problems. However, improved cultivars with better form, the ability to retain foliage during drought, and unique flowering and foliage characteristics are in demand. `Plum Surprise' is a new cultivar of Abelia that was developed at the University of Georgia in response to these needs. `Plum Surprise' is a seedling selection from the cross `Edward Goucher' × `Francis Mason'. It forms an unusual weeping, spreading mound with fine-textured foliage. In March and April, foliage is yellow-green with scattered red/purple leaves. In late spring, the foliage becomes emerald green, changing to a lighter green throughout the summer. New stem growth is red. The most striking features of `Plum Surprise' are the fall and winter foliage color and the evergreen habit of the cultivar. As autumn progresses, the outer shoots and leaves transform to red/purple or crimson, while the inner foliage is bright emerald green. Foliage is glossy in the winter, and a deep purple or burgundy color. `Plum Surprise' is a relatively light bloomer, with flowers scattered individually or in pairs. The flowers appear white, but on close examination have a purple blush with a pale yellow throat. `Plum Surprise' is noteworthy for its heat and drought tolerance. In both the summers of 2002 and 2005, when check cultivars had lost 50% to 80% of their foliage, `Plum Surprise' exhibited little leaf drop. `Plum Surprise' performs well in a pot under nursery conditions. The foliage cascades down over the pot, making an attractive appearance in both form and color.

Azalea lace bug (ALB) is a significant pest on azalea, with feeding injury causing speckling and discoloration on affected leaves. Feeding damage also results in a reduction of stomatal gas exchange and leaf chlorophyll content, postulated to diminish growth and flowering rates. In azalea, specific lipid components of the plant cuticle have been implicated in ALB resistance of R. canescens. In this study, epicuticular leaf wax was extracted from the leaves of four azalea genotypes, divided into two groups: a resistant group including R. periclymenoides and `Fourth of July' and a susceptible group including R. austrinum and `My Mary'. Leaf wax was extracted and resuspended in solution for application to all entries in a full diallel manner, including controls of solution only and no treatment. Each genotype–solution treatment included 10 replications. The leaf wax solution was applied to each replication (leaf) by painting the solution on one side of the midrib, yet on both abaxial and adaxial surfaces. Two leaves attached to a stem and four female adult ALB were placed in separate 32-mL sealed cups. Experimental conditions were 24 °C and 12-hour daylength for 96 h, at which time the number of live adults, frass spots, and eggs were counted. Data revealed that application of leaf wax solution had an impact on the level of frass and egg deposition by ALB in both resistant and susceptible genotypes. The effect was most pronounced when a solution of resistant genotypes was placed on susceptible genotypes, as the application resulted in lower numbers of frass spots and eggs compared to the nil control. However, an increase in frass and eggs was observed when extract of susceptible genotypes was applied to resistant genotypes.

A regeneration system for 'Pumila' pampas grass (Cortaderia selloana Schult.) that yields plants over many months and allows control of morphogenesis was developed. Immature inflorescence explants cultured for three 4-week passages on MS basal medium supplemented with 4.5 μM 2,4-D and 8.9 μM BA yielded a dark green callus that organized into shoot primordia. Rate of shoot development was increased after transfer of shoot primordia to medium supplemented with 9.8 μM IBA. Subculture every 4-6 weeks onto medium containing IBA yielded a continuous production of shoots. Control of morphogenesis was achieved by transferring cultures to medium containing 4.5 μM 2,4-D and 8.9 μM BA for shoot bud proliferation and to medium containing IBA for shoot production.

Rhododendron section Pentanthera has traditionally been viewed as a group of closely related species due to the relative lack of distinctive morphological characteristics separating species and numerous reports in the literature of artificial and natural fertile hybrids that produce fertile progeny. Significant variation within species has created difficulties in efforts to assemble these taxa into well-defined groups. Genetic relationships among cultivated specimens of the 15 currently recognized species in Rhododendron section Pentanthera were derived from sequence comparisons of the internal transcribed spacer (ITS) region. Sequences of the entire ITS region including ITS1, ITS2, and the 5.8S subunit were generated by direct sequencing of polymerase chain reaction (PCR) amplified fragments. Rhododendron vaseyi A.Gray, Rhododendron section Rhodora (L.) G.Don was used as an outgroup. Aligned sequences of the 16 taxa resulted in 690 characters. A distance matrix of sequence divergence was calculated using Kimura's two parameter model. A bootstrap analysis was performed and a phenogram was constructed using MEGA. A phenetic assay rather than a phylogenetic analysis was performed because the ITS region contained only eight (1.16%) phylogenetically informative sites. The entire ITS region contained 41 variable sites (5.94%). Five species had identical ITS sequences. Seven additional species differed only by one or two base pair substitutions and/or the addition or deletion of one or two base pairs. R. luteum Sweet, R. occidentale A. Gray, R. molle (Blume) G.Don, and the outgroup, R. vaseyi had noticeable variation (base substitutions, additions, and deletions) compared to the other species. Divergence values among the taxa were extremely low, ranging from 0.00% to 3.51%. This molecular data, and previous hybridization studies, do not support the accepted taxonomic treatment of the section.

While the recommended time to prune abelia is before spring growth initiates, the actual pruning time is often variable and dependent upon labor and plant appearance. As abelia suffers from freeze damage north of zone 8A, pruning may have an impact on the level of freeze damage. Six Abelia genotypes were established in replicated field plots in Griffin, Ga., in 1999. On 3–4 July 2003, half the individuals of each genotype were severely pruned (75% of growth removed). Subsequently, 80 uniform-sized stem tips were randomly collected from plants of each genotype–treatment combination once per month from Oct. 2003 through Apr. 2004. Stem sections were exposed to predetermined temperatures ranging from –3 °C to –27 °C in a temperature bath. The number of stem sections killed in each of two replications out of four possible stem sections was recorded (0 = none dead; 4 = all dead). Data were analyzed with SAS using the Genmod procedure to acquire seasonal results as well as with PROC GLM and means separation to acquire monthly results. Using the Genmod procedure, all genotypes with the exception of `Canyon Creek' were significantly more cold tolerant in unpruned compared to pruned treatments. In this study, Dec. 2003 was the first month with temperatures below freezing at the test site. Proc GLM analysis indicated a significant difference between the pruned and unpruned treatments in Dec. 2003–Feb. 2004. Results of the Proc GLM analysis for the months of Oct. and Nov. 2003 as well as Mar. and Apr. 2004 were nonsignificant (P < 0.05) due to an absence of cold acclimation. These results indicate that mid-season pruning of Abelia genotypes can significantly reduce cold hardiness and lead to serious stem dieback in pruned plants.

Abelia ×grandiflora is a drought-tolerant, pest-resistant, flowering shrub that has long been used as a foundation plant. Interspecific hybridization has produced seedlings with an assortment of morphological traits, allowing for development of new cultivars with unique or improved qualities. `Raspberry Profusion' and `Lavender Mist', developed at the University of Georgia, are seedling selections of `Edward Goucher' × Abelia chinensis. `Raspberry Profusion' is a very heavy and very early bloomer. Panicles are large and showy with fragrant pink flowers and raspberry-colored sepals. Flowering begins in early May and becomes very heavy by early June. The bright-colored sepals remain on the plant throughout the summer. Summer foliage is a medium to dark green color. In a pot, `Raspberry Profusion' blooms early and heavily. `Lavender Mist' is a heavy bloomer, with clusters of fragrant lavender flowers beginning in mid-June, and continuing into autumn. Sepals are a straw-green color at the base, becoming rose at the tips. Summer foliage is gray-green. `Lavender Mist' performs well in a pot, forming a gray-green mound contrasting with the lavender blossoms scattered around the plant. Leaves on both cultivars are glossy, particularly from mid-summer through autumn. Both plants tend to be mostly deciduous in the winter. Laboratory evaluations of cold hardiness in Griffin, Ga., during Winter 2003–04 revealed a mid-winter hardiness of –18 °C to –21 °C for `Raspberry Profusion' and –15 °C to –17 °C for `Lavender Mist'. These plants develop into dense compact shrubs following pruning and establishment in the landscape.

Azalea Lace Bug (ALB) is a significant pest on azalea species. ALB feeding injury causes a stippled appearance on the leaves of susceptible genotypes from late spring until leaf drop. To determine whether leaf surface lipids are a factor in determining resistance or susceptibility to ALB, epicuticular leaf wax was extracted from the leaves of eight azalea genotypes, half with resistance and half susceptible to ALB. Leaf wax from each genotype was extracted and re-suspended in an 2 ethanol: 1 water solution for application to all entries in a full diallel manner, including a control of solution only. Each treatment included three replications. The leaf wax solution was applied to each replication (single leaf) by painting the solution on one side of the midrib, on both abaxial and adaxial surfaces. By applying solution to one side of the leaf, the untreated leaf surface served as a control. Each leaf and two female ALB were placed in separate 50-mL sealed tubes at 24 °C and 12-hour daylength for 48 hours, at which time the number of live adults, frass spots, and eggs were counted. Frass and egg data were recorded separately for treated and untreated sides of each leaf. The application of leaf wax solution had an impact on the level of frass and egg deposition by ALB in all genotypes. The effect was most pronounced when solution of resistant genotypes was placed on susceptible genotypes, resulting in lower numbers of frass spots and eggs. The solution alone had little effect on frass or egg numbers. This research acknowledges that a major constituent of an azalea's resistance or susceptibility to ALB is via epicuticular wax components.

Azalea lace bug, Stephanitis pyrioides (Scott), is a major pest on azalea. Adults and nymphs feed and oviposit on the underside of the leaves, causing a stippled appearance when viewed from above. Previous field and laboratory screenings of 17 taxa of deciduous azalea, including representatives of 11 species, have identified a range of resistance to lace bug. One of the most resistant plants observed was of the species R. canescens. The interveinal region on the underside of the leaves of this plant is highly pubescent. This plant was crossed to a susceptible plant of R. viscosum (formerly R. serrulatum), which was glabrous on the lower leaf surface. The resulting seeds were planted in 1996, and the seedlings were transplanted to the field in 1998. In Sept. 1999, a laboratory bioassay was conducted to determine the resistance levels of these progeny. Five cuttings, each with two leaves, were collected from each plant, including the parental genotypes. Two female lace bugs were transferred onto the leaves of each cutting and the leaves were enclosed in a plastic cup with mesh for ventilation. After 5 days, the number of live bugs and number of eggs per cutting were counted. The percent damage from feeding was estimated. To determine whether pubescence was correlated with lace bug resistance, two terminal leaves were collected from each plant, and interveinal leaf hair density was calculated. Results from the laboratory bioassays revealed a high degree of susceptiblity to lace bug among these seedlings. Most of the progeny were pubescent, indicating no relationship between leaf hair density and resistance.

Flowering evergreen shrubs that are compact and resistant to pests are in great demand in the nursery and landscape industries. The genus Abelia contains 30 species that vary in many traits including flower color, growth habit, and hardiness. Abelia × grandiflora (Andre) Rehd. and its cultivars are the most widely grown Abelia taxa and are characterized by pest resistance, an abundance of pinkish white flowers, long flowering period, and glossy evergreen foliage. Interspecific hybridization among Abelia × grandiflora, its cultivars, and other species in the genus Abelia offer the potential for new cultivars; however, seed germination within the genus has been described as slow and inconsistent. Experiments were conducted to test procedures to increase germination percentages and rates. Each Abelia seed is enclosed in a leathery achene. The effect of achene removal was examined in combination with cold, moist stratification for 60 days at 4 °C, immersion in 100 ppm gibberellic acid for 24 h, and no treatment. Treatments were replicated five times with 15 seeds per replication. Seeds were sown on sphagnum peat, and grown under mist in the greenhouse. Weekly germination counts were recorded for 8 weeks. Seeds with attached achenes germinated at a significantly higher percentage than those without achenes. Cold, moist stratification and gibberellic acid treatments were not significantly different than the control. No significant differences were found within the achene treatments for relative rate of emergence, but significant differences were found for the time until 90% of final emergence was reached.

The genus Abelia contains ≈30 species, but A. × grandiflora, its cultivars, and A. `Edward Goucher' are the primary taxa grown. The nursery industry has stated that Abelia R. Br. taxa are important economically, and new selections or cultivars with increased cold hardiness, richer pink-rose flower colors, unique foliage colors, and compact habits are desired. Breeding and selection work in the genus is very limited due in part to limited access to germplasm. Pollen storage enables breeders to cross taxa with incongruent flowering cycles, save time and resources by eliminating the need to grow vast amounts of plant material, and incorporate otherwise unavailable germplasm into a breeding program. An experiment was conducted to determine the optimum levels of temperature and humidity for the long-term storage of A. chinensis and A. × grandiflora `Golden Glow' pollen. Temperature and humidity levels were analyzed by incubating undesiccated pollen of a given taxon at four humidity levels (0%, 50%, 80%, and 100%) for 72 h at 5 °C. Following incubation, the pollen was stored in glass vials at each of the following temperatures: 5, -20, and -70 °C. All combinations of temperature and humidity were tested. Pollen viability was assessed after 60 days by in vivo germination tests on styles. Abelia chinensis pollen germinated following storage at all temperature and humidity levels. Pollen of A. × grandiflora `Golden Glow' pollen germinated following all treatments except storage at -20 °C.

Azalea lace bug (Stephanitis pyrioides) is the most serious pest on azalea. Results of laboratory bioassays and field evaluations of 17 deciduous azalea taxa have identified three resistant taxa: R. canescens, R. periclymenoides, and R. prunifolium. Highly susceptible taxa are `Buttercup', `My Mary', R. oblongifolium, and the evergreen cultivar `Delaware Valley White'. To determine whether in vitro techniques would have potential value in screening or selecting for resistance, or for the identification of morphological or chemical factors related to resistance, an in-vitro screening assay was developed. In-vitro shoot proliferation was obtained using the medium and procedures of Economou and Read (1984). Shoots used in the bioassays were grown in culture tubes. Two assays were developed: one for nymphs and one for adult lace bugs. To assay for resistance to nymphs, `Delaware Valley White' leaves containing lace bug eggs were disinfested with 70% alcohol and 20% commercial bleach, and incubated in sterile petri plates with moistened filter paper until the nymphs hatched. Five nymphs were placed in each culture tube, and cultures were incubated for about 2 weeks, or until adults were observed. To assay for resistance to adults, five female lace bugs were placed in each culture tube and allowed to feed for 5 days. Data collected on survival and leaf damage was generally supportive of laboratory bioassays and field results. Adult lace bugs had a low rate of survival on resistant taxa. Survival of nymphs was somewhat reduced on resistant taxa.

Azalea lace bug (Stephanitis pyrioides) is the most serious pest on azalea. Both evergreen and deciduous azaleas are susceptible, though more resistance has been observed in the deciduous. To identify genes for resistance, fourteen deciduous azalea species, three deciduous azalea cultivars derived from complex hybrids, and one evergreen cultivar were planted in a randomized complete-block design under mixed deciduous trees in the fall of 1994. Each block was replicated 12 times. In the spring and summer of 1995, azalea lace bugs were introduced onto branches of six plants of each of the taxa. One month later, and again in the fall of 1996, the percentage of infected shoots per plant was measured. Very little damage from azalea lace bug was observed on the R. canescens, R. periclymenoides, and R. prunifolium plants, while `Buttercup', `My Mary', R. japonicum, and R. oblongifolium had the greatest damage. The cranberry rootworm, Rhadopterus picipes, damages many woody ornamentals, including some azalea species. The injury appears as elongated cuts on the leaves, and is most severe on plants growing under dense canopies. The cranberry rootworm has been observed in this azalea field plot. Plants were evaluated for damage in June 1995 and 1996. Cranberry rootworm damage was most severe on `Buttercup', R. japonicum, R. prinophyllum, and R. calendulaceum, while the evergreen azalea `Delaware Valley White' was the most resistant.

Deciduous azaleas have been gaining popularity because of their showy floral displays and adaptability to adverse environmental conditions. However, an absence of distinguishing morphological characteristics, combined with the wide variability present in most species, has created difficulties in efforts to unambiguously identify the different species. Various DNA isolation protocols were tested in order to determine the most effective methods for isolation of DNA from 22 taxa of Rhododendron for subsequent PCR amplification. DNA yields from the various isolation methods varied widely. A minimum of 50 ng/μL of template DNA was necessary for PCR amplification under standard amplification conditions. Results indicated that the effect of tissue age on the efficiency of DNA isolation was taxa-dependent. For most species, extraction of DNA from freshly harvested young leaf tissue resulted in the highest DNA yields. However, DNA yields from R. serrulatum, R. atlanticum, and R. viscosum `Lemon Drop' were highest when mature leaf tissue was used. Primers designed to amplify the internal transcribed spacer (ITS) region of the nuclear ribosomal genes and the psbD, trnK, and 16S chloroplast genes were tested in various PCR reaction mixes in order to optimize reaction conditions for amplification. Primers to both the ITS and the psbD gene resulted in satisfactory amplification in the presence of 1.5 mM MgCl2 and 50 ng template DNA.

Managers and employees of landscape maintenance and lawn care industry (LM/LC) applying pesticides can prevent pollution. Adequate information about application of herbicides, insecticides, fungicides, and nematicides is a prerequisite for proper application. A survey, prepared by an interdisciplinary research team “Ornamentals Working Group,” was implemented in 1994 to Atlanta metro area firms. The gross return rate was 25.4%. The majority of respondents had 10 or fewer years of experience in providing landscape services; had at least 13 years of schooling; and were in their thirties or forties. The categorical nature of dependent variables suggested ordered probit procedure as the statistical estimation method. Independent variables included characteristics of the respondent, firm characteristics, and information sources about the application of a specific pesticide. Extension and research personnel and commercial representatives were important information sources about insecticide and fungicide application. The use of all three sources of information by the LM/LC industry seems to depend on pesticide type, with commercial representatives, and extension and research personnel often acting as complementary information sources.

Previous studies indicated that the number of shoots formed per nodal explant varied significantly depending upon the type of culture container used. Amount of media per container and amount of time that media was autoclaved were variables that differed among the containers. To determine the cause for the container effect on shoot number, a study was conducted in which autoclave time and amount of media per container were the same for all tested containers. Media was autoclaved in 500-mL batches for 30 min, then poured in 30-mL aliquots into sterile containers. Containers tested were plastic petri plates, GA-7 Magenta vessels and glass jars. Depth of the medium was 5 mm in plates, 8 mm in vessels, and 12 mm in jars. Nodes from in vitro grown shoots of `Triumph', `Regale', and `Fry' were cultured on Murashige and Skoog salts and vitamins with 2 mg·L–1 BA and 8 g·L–1 agar. Results indicated that the greatest number of shoots formed in the jars. In a second study, nodes were cultured on petri plates containing 30 mL of medium (depth 5 mm) or 70 mL (depth 12 mm). Two to three times more shoots formed on the plates with the greater amount of medium. These studies indicate amount and depth of medium are factors influencing shoot number.

Azalea lace bug is the most serious pest of cultivated azalea. Though deciduous azaleas are generally considered to be more resistant to lace bug than are evergreen azaleas, some variation in resistance has been reported. The identification of the genetic and physiological basis of resistance is important to eventual development of resistant cultivars of both the deciduous and evergreen azaleas. The first step in this program is to evaluate a wide range of deciduous azaleas for level of resistance. Laboratory evaluations were conducted on nine species and two hybrid cultivars of deciduous azalea and a known susceptible cultivar of evergreen azalea, `Delaware Valley White'. Oviposition rate, rate of egg hatch, number of nymphs surviving, and percent damaged leaf area were evaluated for each of the tested genotypes. Results indicated a wide range of susceptibility, with R. canescens and R. periclymenoides plants highly resistant to infection, while R. atlanticum and R. viscosum were highly susceptible.

Nodes from in vitro grown shoots of `Regale' and `Triumph muscadine grape (Vitis rotundifolia) were cultured in 25 × 95-mm glass vials, 25 × 150-mm glass culture tubes, 55 × 70-mm glass baby food jars and 100 × 25-mm plastic petri dishes. Culture medium consisted of Murashige and Skoog salts and vitamins, 80 mg/l adenine sulphate, 170 mg/l sodium phosphate, 2 mg/l BA and 8 g/l agar. Amount of medium dispensed was 8 ml per vial, 18 ml per culture tube and jar, and 70 ml per petri dish. Containers were covered with clear plastic lids, sealed with parafilm, and placed under fluorescent lights for six weeks. The number of shoots per explant that formed in petri dishes was three to four times greater than those formed on explants in vials, tubes and jars. However, the number of nodes per shoot were fewer in dishes than in the other containers. Callus formation was excessive in jars to the detriment of shoot production. Vials and tubes had small amounts of callus, while little or no callus was observed in dishes.