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  • Author or Editor: Thomas A. Fretz x
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Alachlor (2-chloro-2′,6′-diethyl-N-(methoxymethyl)-acetanilide), diphenamid (N,N- dimethyl-2,2-diphenylacetamide) and napropamide (2-(α-naphthoxy)-N,N-diethylpropionamide) provided excellent broadleaf and grass weed control. Alachlor significantly injured the ‘St. John's Fire’ Salvai while diphenamid caused moderate injury to ‘Golden Torch’ Celosia. Both trifluralin (α,α,α-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine) and DCPA (dimethyl tetra-chloroterephthalate) provided less than acceptable control of broadleaf weeds at the rates employed, but neither caused significant injury to any of the 15 cultivars of transplanted annual bedding plants used in this study.

Open Access
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Dry wt of Japanese holly (Ilex crenata (Thunb.) cv. convexa Makino.) decreased significantly as the density of competing weed species increased. One redroot pigweed plant (Amaranthus retroflexus L.) reduced the dry wt of Japanese holly by 47% in 2.4 liter and 30% in 6.0 liter containers and 1 plant of large crabgrass (Digitaria sanguinales (L.) Scop.) caused reductions in dry wt of Japanese holly of 60% in 2.4 liter and 35% in 6.0 liter containers.

Open Access
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Media temperatures surpassed 120°F in 1 gal nursery containers of both steel and high density polyethylene without plants when exposed to direct solar radiation. White, silver, and yellow exterior colors significantly reduced media temperatures when compared to darker colored metal containers. Surface barriers of black or clear polyethylene increased media surface temperatures significantly while aluminum foil and pressed white fiberglass disks had no effect on media temperatures in comparison to containers without surface barriers. In a 6 × 6 container to container configuration, those on the southern exposure exhibited significantly higher media temperatures than similar containers on the northern exposures or toward the center of the configuration. None of the artificial media examined significantly reduced temperatures in the containers.

Open Access
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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
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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

The Ohio Cooperative Extension Service and The Ohio State University sponsored a symposium December 9-10, 1977 for members of the nursery production and scientific communities to update their knowledge and exchange ideas as it related to the winter storage of woody ornamentals. The symposium participants discussed the physiology of winter storage, pre-storage practices, determining maturity and prediction of harvest dates, acclimating plants to storage, principles of common and refrigerated storage, construction and orientation of storage structures, poly-coverings, disease control, anti-transpirants, minimum-heat, thermoblankets, heat saving techniques, and future needs. A summary of the discussions as well as research ideas are presented in this report. Copies of the proceedings of the Woody Ornamentals Winter Storage Symposium can be obtained for $5.00. Persons interested should enclose a check payable to Storage Symposium to Dr. Elton M. Smith, Department of Horticulture, 2001 Fyffe Court, Columbus, Oh, 43210.

Open Access

Abstract

Horticulture in the Commonwealth of Virginia has been greatly influenced by the topography of the state, and by the heritage of early settlers. In the Handbook of Virginia, published in 1866, 6 “great natural divisions” were recognized: the Tidewater, Middle Virginia, Piedmont, the Blue Ridge, the Shenandoah Valley, and Appalachia. These divisions, which rise in altitude from east to west, were said to have “differences of climate, soil production and require separate considerations in every respect.” Superimposed on these regions were the culture and national heritage of the settlers which had a great influence on the scope and scale of the state's agricultural development.

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