Search Results

You are looking at 1 - 10 of 11 items for :

  • Author or Editor: Thomas A. Fretz x
  • Journal of the American Society for Horticultural Science x
Clear All Modify Search
Author:

Abstract

Monoterpenes from the foliage of Juniperus horizontalis ‘Plumosa’ (Andorra Juniper.) grown under varying nitrogen levels and supplemental night lighting were measured using gas chromatography. Increasing photoperiod significantly increased the quantity of α-pinene and γ-limonene, while camphene, β-myrcene and linalool decreased. Other monoterpenes, including β-pinene, sabinene, terpinolene and α-terpineol were not significantly affected by photoperiod. Only α-terpineol showed a significant increase in relation to increasing level of N fertilization. All other monoterpenes decreased or remained unchanged as a result of increasing N levels.

Open Access
Author:

Abstract

Seven herbicides were evaluated for their safety and efficacy on 5 species of container grown nursery stock. During both growing seasons all materials except isopropyl-m-chlorocarbanilate [chlorpropham] at 2.2 and 8.9 kg/ha, chlorpropham at 2.2 and 8.9 kg/ha + P-chlorophenyl-N-methylcarbamate [PPG-124] at 0.4 and 1.7 kg/ha, resp., and N,N-dimethyl 2,2-diphenylacetamide [diphenamid] at 5.6 kg/ha gave satisfactory long season (163 days) broadleaf weed control. Long season grass weed control in nursery containers was achieved both years with 2,6-dichlorobenzonitrile (dichlobenil) at 13.4 kg/ha, α,α,α-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine (trifluralin) at 2.2 and 8.9 kg/ha, S-ethyl dipropylthiocarbamate (EPTC) at 5.6 and 22.4 kg/ha, chlorpropham + PPG-124 at 8.9 + 1.7 kg/ha and diphenamid at 22.4 kg/ha. Both azalea species employed in the test exhibited severe chlorosis, necrosis, and stunting when dichlobenil at 13.4 kg/ha and EPTC at 22.4 kg/ha were employed. Japanese holly and ‘Sasanqua’ camellias were severely injured by dichlobenil at 13.4 kg/ha, while ‘Hetzi’ juniper was tolerant to all herbicides at all rates employed.

Open Access

Abstract

Pollen specimens from 8 ornamental crabapples (Malus spp.) were compared using the scanning electron microscope (SEM) to determine if they, like apple cultivars, can be distinguished by pollen characters. All pollen grains were approximately equivalent in size, tricolpate, elliptical in shape, with tectate-perforate exine type. Exine riding was superficially similar among all 8 crabapples, but close examination revealed sufficient detail to distinguish between them. Pollen from 4 of the 8 crabapples, M. baccata var. mandshurica (Maxim.) C. K. Schneid., M. × purpurea (Hort. Barbier) Rehd. ‘Lemoinei’, M. × robusta (Carriere) Rehd. and M. Sargenta Rehd. possessed collared perforations. Among these M. baccata var. mandshurica and M. × purpurea ‘Lemoinei’ pollen had grains with parallel, unbroken exine ridging, while M. × robusta and M. sargentii grains commonly exhibited whorling of ridges. Spacing between exine ridges were wider on pollen grains of M. baccata var. mandshurica than on those of M. × purpurea ‘Lemoinei’, but M. × robusta and M. sargentii could not be distinguished using pollen characters alone. The remaining 4 crabapples lacked collared perforations and were further subdivided by perforation frequency. M. floribunda Siebold ex Van Houtte and M. × purpurea (Hort. Barbier) Rehd. pollen displayed a large number of simple perforations while pollen from M. × purpurea ‘Aldenhamensis’ and M. × zumi calocarpa (Matsum.) Rehd. yielded lower perforation frequencies. M. floribunda pollen had more closely spaced exine ridges than M. × purpurea. M. × purpurea ‘Aldenhamensis’ differed from M. × zumi var. calocarpa in that its pollen generally had larger perforations.

Open Access

Abstract

Leaf and terminal bud samples from 9 crabapples were examined using the scanning electron microscope (SEM) for the purpose of establishing consistent, identifying morphological detail Crabapples utilized in the study included: Malus × purpurea (Hort. Barbier) Redh.; M. × purpurea ‘Aldenhamensis’; M. × purpurea (Hort. Barbier) Rehd.; M. × purpurea ‘Aldenhamensis’; M. × purpurea ‘Lemoinei’; M. baccata var. mandshurica (Maxim.) C. K. Schneid.; M. floribunda Seibold ex Van Houtte; M. hupehensis (Pamp.) Rehd.; M. × robusta (Carriere) Rehd.; M. sargentii Rehd.; and M. × zumi var. calocarpa (Matsum.) Rehd. Overall, characters observed on terminal buds were less useful than leaf features. Only 4 species exhibited distinctive bud characters. Terminal bud surfaces of M. × robusta displayed unique networks of fibrillar wax. M. baccata var. mandshurica and M. × zumi var. calocarpa buds had defined stomatal structures. M. hupehensis exhibited singular invaginations in the bud epidermis. All crabapple leaves examined were hypostomatic, and all stomata appeared anomocytic. Stomatal characteristics most definitive for categorization were size and frequency. Adaxial and abaxial trichomes were similar in structure and were uniform among all species and cultivars. Observed types of abaxial cuticular striations were very useful as identification aides. Seven of the 9 crabapples could be characterized by foliage features alone.

Open Access

Abstract

Soluble leaf carbohydrates, macronutrient elements and growth responses to 3 levels of light were studied on field grown plants of Ilex opaca Ait. cv. Miss Helen. Soluble D-fructose, α-D-glucose, B-D-glucose and sucrose reached a maximum concentration expressed as a percentage of the dry weight of leaf tissue during the winter sampling periods, followed by a decline as bud-expansion approached. The maximum concentration of soluble D-galactose was found in newly matured leaf tissue. Soluble D-fructose, α-D-glucose, B-D-glucose and sucrose levels were not effected by the shade environments. The level of D-galactose increased under the shaded environment as compared to full sun plants.

P and K levels in the leaf tissue were at high concentrations in newly matured leaf tissues, while Ca and Mg were at low levels. Both K and Mg levels were observed to be higher in leaf tissue from plants grown under the 92% shade conditions compared to full sun plants.

Stem diameter was significantly reduced under the 92% shade conditions, while leaf size of plants grown under both 50% and 92% shade was significantly increased. Flower production was significantly reduced in plants grown under the 92% shade conditions.

Open Access

Abstract

Procedures were developed to extract protein and active enzymes from rose leaves. A suitable extraction medium, extraction time, and sample application rate was determined for each system in which bands could be separated. Sixteen enzyme systems and anionic protein were investigated, with only anionic protein, peroxidase, esterase, malate dehydrogenase, cytochrome oxidase, phenoloxidase, and polyphenoloxidase producing clear bands. Existing staining techniques were adequate for staining cytochrome oxidase, phenoloxidase, and polyphenoloxidase activity, but modifications of the reported anionic protein, peroxidase, esterase and malate dehydrogenase stains were required. Isoenzyme changes which occur during 0, 9, 12, and 16 weeks storage are discussed.

Open Access

Abstract

Protein and active enzymes were extracted from leaves of 8 rose cultivars. Extracts were run on polyacrylamide gels and stained for total protein, peroxidase, esterase, malate dehydrogenase, cytochrome oxidase, phenoloxidase, and polyphenoloxidase. Three leaf positions on each cultivar were sampled in an attempt to determine a sampling standard. Because of differences in growth habit among the cultivars, and different optimum locations for the enzymes, a standard location could not be set. Banding data were tabulated and used to prepare coefficient of similarity values and flow charts showing separations. All cultivars could be distinguished by differences in their enzyme banding patterns if results from several systems were employed.

Open Access

Abstract

Excessive accumulation of Cd or Zn in white pine (Pinus strobus L.), red maple (Acer rubrum L.), and Norway spruce (Picea abies L.), resulted in reduced root initiation, poor development of root laterals, chlorosis, dwarfism, early leaf drop, wilting, and necrosis of current season’s growth. Positive correlations existed between nutrient culture levels and tissue accumulation when plants were grown in sand. White pine seedlings accumulated more Cd and Zn than either red maple or Norway spruce when compared in similar experiments. White pine appeared to be more tolerant of Cd and Zn accumulation than either red maple or Norway spruce since visual phytotoxicity symptoms were observed only at the higher treatment levels. Accumulation of Cd and Zn from a medium of 2 sand: 1 soil: 1 perlite by volume was also observed.

Open Access

Abstract

Carbon-nitrogen relationships and pH of 2 milled hardwood bark-amended media were influenced similarly by 3 N sources, (NH4)2SO4, NH4NO3, and Ca(NO3)2 incorporated at 0, 0.89 and 1.78 kg/m3 prior to composting. Nitrogen source did not affect overall growth; however dry weight and growth index of Cotoneaster dammeri Schneid cv. Royal Beauty increased with increasing N rate. Source and rate of N had little effect on the foliar analysis, and all values were within the acceptable range for woody ornamentals.

Open Access

Abstract

N, N-dimethyl-2, 2-diphenylacetamide (diphenamid) and α, α, α,- trifluoro-2, 6-dinitro-N, N-dipropyl-p-toluidine (trifluralin) caused no injury to transplanted petunias (Petunia hybrida Vilm.) or marigolds (Tagetes patula L.) when incorporated in a mulch. Satisfactory broadleaf and grass weed control as denoted by indicator crops was achieved with both of these herbicides. Dichlobenil, 2,6-dichlorobenzonitrile, caused severe injury to both petunia and marigold transplants when applied in the herbicide-mulch combination. Control of broadleaf and grass indicator weeds with dichlobenil was excellent at all rates. Dimethyl tetrachloro terephthalate (DCPA) resulted in no visible injury to the marigold or petunia transplants when used in the herbicide-mulch combination, but control of grass and broadleaf indicator weeds was poor. When diphenamid and dichlobenil at the same rates were incorporated on peat moss, licorice root, pine bark or sugar cane mulches, no differences were observed among the mulches in regard to their ability to control weed growth.

On established nursery stock, 2-chloro-4, 6-bis (ethylamino)-s-triazine (simazine) plus DCPA, simazine plus diphenamid, and 3-(3, 4-dichlorophenyl)-1, 1-dimethylurea (diuron), applied directly to the soil surface performed better than the herbicide-mulch combination at the lower rates. At higher rates, both the direct spray on the soil surface and the herbicide-mulch combination performed satisfactorily.

Open Access