Abstract
Shoot tip explants of 12 woody species and cultivars of Rosaceae were cultured in vitro on Linsmaier and Skoog nutrient medium containing benzylamino purine (BA). Greatest shoot proliferation occurred in the presence of 0.1 to 2.5 mg/liter BA and was species-dependent. Root initiation was promoted when 1 to 10 mg/liter indolebutyric acid (IBA) was added to the medium. Rooting increased when cultures were incubated in the dark for 1 week prior to illuminated incubation.
Abstract
The citrus whitefly, Dialeurodes citri (Ashmead), prefers Gardenia jasminoides Ellis cv. August Beauty to G. jasminoides cv. Radicans, Viburnum odoratis- simum Ker-Gawl, and Ligustrum sinense Lour. cv. Variegata for egg deposition. Mean numbers of citrus whiteflies found in subsequent life stages (after the egg) remained significantly higher on G. jasminoides cv. August Beauty. These four host plants of the citrus whitefly are major production and landscape items in the south; therefore, segregation of cultivars most heavily infested by the pest is an important consideration when planning control strategies.
Abstract
Rooted cuttings of Pilea cadierei Gagnep. & Guillaum., Chrysanthemum morifolium Ramat. cv. Giant #4 Indianapolis White, Hedera helix L. cv. Thorndale, Pachysandra terminalis Siebold & Zucc. and young plants of Juniperus chinensis L. cv. Mint Julep and Ligustrum X vicaryi were exposed for 3 weeks to either water mist or mist to which a complete all soluble fertilizer (23N-8P-14K) was added; roots and root medium were protected from the mist. The N, P and usually K content of all plants increased after foliar application of nutrients. Pilea, pachysandra and Hedera increased in height, dry weight, and number of lateral breaks; privet increased in height and overall greening of the foliage occurred. The optimum concentration of foliar-applied nutrients was 600 ppm for Pilea, 750 ppm for Hedera and pachysandra and 300 ppm for Ligustrum; higher concentrations caused foliage injury. Injury occurred to chrysanthemum and juniper at all concentrations studied. Cuticle thickness and plant tolerance to foliar nutrition were not correlated.
Compost has great potential for use in horticulture; however, the relationship between compost feedstock materials and resultant compost characteristics must be well understood. Research examining plant growth response from the addition of compost to container growing media is limited. This research had two parts: the first part examined the relationship between compost feedstock materials and resultant mature compost characteristics. The second part investigated plant growth responses when compost replaced the peat component of container growing media. Two feedstock treatments were aerobically composted in turned windrows. Compost characteristics examined include pH, EC, C:N Ratio, Solvita Maturity, and several biological characteristics (total and active bacteria, total and active fungi, protozoa, spore forming bacteria, E. coli O157:H7, and total coliformic bacteria). To examine plant growth response, compost was substituted for peat (from 0%-40% by total volume) in container growing media. Crops tested were Antirrhinum majus `Rocket White', Viola × wittrockiana `Crown Azure', Oriental Hybrid Lilium `Siberia', and Chrysanthemum × grandiflorum `Yellow Kodiak'. Quantitative plant growth response measurements (shoot fresh and dry weight, percent root necrosis, flower number, and flower size) were recorded and compared by treatment. Despite initial feedstock differences between the two compost treatments, both resulted in similar compost biology and species richness. Coliformic bacteria and E. coli O157:H7 levels were below detection limits in final compost. Choice of compost feedstock materials had a significant effect on the chemical characteristics of the finished product. Compost replacement for peat resulted in plant growth greater than or equal to those of the control treatment.
The Univ. of Connecticut has designed a website that will help facilitate the learning of landscape plant material. The main objective of this site is to help students taking plant identification courses in New England's land-grant universities and one private college. Virtual Campus Plant Walks have been developed to address budget constraints, student demands for technology integration in the classroom and to make use of the pedagogical benefits of the internet medium. The Virtual Campus Plant Walks are on-line walks that have detailed pictures and information given during actual plant walks done in each plant identification laboratory. Students are able to retake the walks at their own pace, reevaluate a plant they are having trouble remembering, or take the walk over the internet for the first time if they were unable to attend lab. Students will now be able to study plant material whenever they want, regardless of the time of day or weather. The educational validity of the walks has been tested for three semesters and the results are favorable. Surveys reveal that 80% believe the website improved their grades and 76% claimed the website decreased their study time. This evidence will promote the continued and expanded use of the website.
Several biological control agents for the control of fungal diseases have recently been commercialized. Do the claims of pest control meet the expectations of the growers? Do the biocontrol agents perform consistently? How do they compare to chemicals? These questions have yet to be answered but recent trials indicate mixed results. In Massachusetts, Mycostop worked well against fusarium stem rot but not against fusarium wilt. Deny (Burkholderia cepacia) did not perform well against Rhizoctonia or Pythium root rot of poinsettia. The following information was taken from the 1997 and 1998 Biological and Cultural Tests for Control of Plant Diseases. In Maryland, zinnia damping-off was controlled by both SoilGard (Gliocladium virens) and Bio-Trek (Trichoderma harzianum). The biocontrols performed as well as the conventional fungicide. In North Carolina, GlioGard (Gliocladium virens) and SoilGard gave only partial control against Pythium and Rhizoctonia damping-off of bedding plants. In Pennsylvania, Greygold (mixture of four microorganisms) did not provide adequate control of Botrytis on geranium. In Georgia, Pythium and Rhizoctonia diseases of a variety of plants were evaluated with SoilGard and RootShield (Trichoderma harzianum). Disease pressure was low and the results varied from inconclusive to both positive and negative. In addition, SoilGard apparently reduced fresh weight of several plant species. RootShield was reported to both increase root weight in one case and decrease root weight in another. In Connecticut, Rhizoctonia root rot of poinsettia was not significantly suppressed with SoilGard, RootShield, or Earthgro, a suppressive growing medium. However, the authors stated that the results indicated that the biocontrols had promise. Results of additional trials will be presented.
Abstract
Chemical growth retardants are unique in the history of chemical regulation of plants. All types thus far used by growers have been synthetics. Unlike many other classes of growth regulators, we have thus far not detected the naturally occurring chemicals that account for the development of dwarf plants. For one reason, dwarf plants may result from reduced or degenerated biosynthetic pathways for the natural production of gibberellin-like compounds. Also, they may result from the synthesis of a number of interrelated compounds, which separately have little effect on growth. In certain combinations and concentrations, however, they affect cell division and expansion control systems. Chemical growth retardants permit a direct approach to growth control by retarding internode elongation without seriously disrupting the growth processes that involve chlorophyll and phytochrome. They permit growers to predetermine the size of the plant for many different uses and have become an integral part of many plant production systems (Fig. 1). Florists’ and nurserymen’s catalogs designate cultivars as particularly responsive to a specific chemical growth retardant.
In two experiments, chinese hibiscus (Hibiscus rosa-sinensis), bamboo palm (Chamaedorea seifrizii), areca palm (Dypsis lutescens), fishtail palm (Caryota mitis), macarthur palm (Ptychosperma macarthurii), shooting star (Pseuderanthemum laxiflorum), downy jasmine (Jasminum multiflorum), plumbago (Plumbago auriculata), alexandra palm (Archontophoenix alexandrae), and foxtail palm (Wodyetia bifurcata) were transplanted into 6.2-L (2-gal) containers. They were fertilized with Osmocote Plus 15N-3.9P-10K (12-to14-month formulation) (Expt. 1) or Nutricote Total 18N-2.6P-6.7K (type 360) (Expt. 2) applied by either top dressing, substrate incorporation, or layering the fertilizer just below the transplanted root ball. Shoot dry weight, plant color, root dry weights in the upper and lower halves of the root ball, and weed shoot dry weight were determined when each species reached marketable size. Optimal fertilizer placement method varied among the species tested. With the exception of areca palm, none of the species tested grew best with incorporated fertilizer. Root dry weights in the lower half of the root ball for chinese hibiscus, bamboo palm, and downy jasmine were greatest when the fertilizer was layered and root dry weights in the upper half of the root ball were greatest for top-dressed chinese hibiscus. Weed growth was lower in pots receiving layered fertilizer for four of the six palm species tested.
Abstract
The disposal of solid wastes from domestic and industrial sources and sludges from sewage treatment plants is an ever-increasing problem. More than 20 years ago our society’s prodigious waste production prompted Vance Packard (65) to characterize our society as a society of “waste makers” going from “riches to rags.” Estimates of the per capita production of waste vary, but it has been noted that the average person is generating more waste each year (97). During the last decade, environmental concerns and energy needs have raised serious questions about our methods of waste disposal. Bohn and Cauthorn (13) have observed that our handling of waste has been unimaginative and expensive.
Abstract
Cold hardiness levels determined for 23 species of plants with bulbs or other specialized underground structures showed great differences in hardiness; Ixia sp., Ranunculus sp., and Sparaxis tricolor were killed at −2°C, while Ixiolirion montanum was first injured at −18°C. In most species of bulbs, the basal plant and roots were the least hardy tissues. Results of this study do not agree with hardiness zone ratings found in the literature for many of the plants tested.