(438) Searching for Cold Hardy Lace-bark Elm (Ulmus parvifolia Jacq.) for Northern Latitudes

The genus Ulmus contains numerous stress-tolerant species, especially those from areas of China with climates similar to various regions of the United States. Lace-bark elm, Ulmus parvifolia, the true Chinese elm, has an extensive temperature distribution range in China and offers great promise as a street tree. The high resistance of this elm to Dutch elm disease and other elm problems makes it an excellent tree for urban landscapes. Two new U. parvifolia cultivars, Athena® and Allee®, are not cold hardy for northern climates and there is a need for new cold hardy lace-bark elms. Screening thousands of seedlings for cold hardiness, upright form, beautiful bark characteristics, and larger leaves will bring the most desirable U. parvifolia cultivars into the green industry. We determined that seed dormancy and the percentage of seed germination of four selected lacebark elms after 2 and 4 weeks were >30% and >50%, respectively. There were significant differences in stem cold hardiness among new lace-bark elms from China (about –32 to –40 °C). Laboratory determination of cold hardiness can provide great advantages over years of field testing. Response to the outdoor temperature in December, January, and February on a seed cold hardiness freezing test showed significant reduction in seed germination, especially at –30 °C. Freezing test of seeds to –40 °C, resulted in lt50 of –3 to –5 °C in December, so, it is less likely that these U. parvifoilia will become invasive in northern latitudes. Invasiveness of these U. parvifolia for higher zones, e.g., 6–8 could be greater and selection of these elms is suitable for zones 5 and lower. Planting these elms in zones 4, 3, and 2 will give us useful information regarding their winter performance.

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146 Cold Hardiness Evaluation of Deer-resistant Thuja plicata for Northern Latitudes

HortScience ◽

10.21273/hortsci.35.3.414f ◽

2000 ◽

Vol 35 (3) ◽

pp. 414F-415

Author(s):

A.M. Shirazi ◽

T.M. Boland ◽

K.R Bachtell

Keyword(s):

Urban Communities ◽

Rural Areas ◽

Cold Hardiness ◽

Limiting Factors ◽

Thuja Plicata ◽

George Washington ◽

Landscape Plants ◽

Northern Latitudes ◽

Public Areas ◽

Freezing Test

The expansion of urban communities to rural areas is leading to an increase of the problem of deer damage. White-tailed deer (Odocoileus virginianus) damage to landscape plants in commercial nurseries, residential and public areas is very widespread. Thuja occidentalis (Arborvitae) is one of the most common landscape plants. It is widely produced by nurseries and used by homeowners in the landscape. However, it is also highly favored by deer for browsing. Thuja plicata (Arborvitae) the Western Cedars is a highly deer-resistant arborvitae. One of the principal limiting factors for new arborvitae for its success in nursery productionand its use in the landscape is cold hardiness (in northern climates). However, the cold hardiness of different Thuja plicata is not known. Deer-resistant Thuja plicata cultivars: `Atroviren', `Cancan', `Elegantissima', `Excelsa', `Gelderland', `George Washington', `Hilleri', `Sunshine', and `Virescens' planted in Sprintg 1998 at The Morton Arboretum research plot in Lisle, Ill. Branch cold hardiness was tested by artificial freezing in Jan. 1999 and 2000. Ice-nucleated samples were placed in an ultra-low temperature and kept at 2 °C overnight, and the temperature then lowered at 5 °C/h to –40 °C, at which time samples were taken out at each test temperature (at 4 °C intervals). After the freezing test, the samples were thawed at 4 °C for 24 h, then planted in a peat and perlite media and kept at 100% humidity in a greenhouse. Samples were evaluated after 2 weeks for visual browning and lowest survival temperature. There were significant differences in coldhardiness between the nine cultivars tested in Jan. 1999. `Elegantissima', `Excelsa'. and `Cancan' were the most hardy (–34 to 40 °C), followed by `Virescens', `Sunshine', and `Gelderland' (–27 to 32 °C), `Hilleri' and `Atrovirens' (–24 to 25 °C). `George Washington' ` was the least hardy (–20 °C) cultivar.

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(237) Hybridization of Hydrangea arborescens and H. involucrata

HortScience ◽

10.21273/hortsci.40.4.1002c ◽

2005 ◽

Vol 40 (4) ◽

pp. 1002C-1002

Author(s):

Keri Jones ◽

Sandra Reed

Keyword(s):

United States ◽

Growth Rates ◽

Cold Hardiness ◽

Rapd Markers ◽

Flower Color ◽

The United States ◽

Early Summer ◽

Eastern United States ◽

Maternal Parent ◽

Cold Hardy

Hydrangea arborescens L., or smooth hydrangea, is a shrub native to the eastern United States that produces large corymbs of pure white flowers in early summer. Rated as hardy to USDA cold hardiness zone 4, it is one of the most cold-hardy members of the genus. Hydrangea involucrata Sieb. is an Asian species that produces lavender-blue flowers in midsummer. This species, which is not widely cultivated in the United States, is only rated as hardy to zone 6 to 7. The objective of this study was to hybridize H. arborescens and H. involucrata for the purpose of combining cold hardiness and flower color. Reciprocal crosses were made between H. involucrata and H. arborescens during Summer 2003. No seed were obtained when H. involucrata was used as the maternal parent. Approximately 500 seeds were collected from H. arborescen × H. involucrata hybridizations, 36 of which germinated. Several of these seedlings were extremely weak and died at a young age. The remaining eight plants have not flowered and all possess reduced growth rates. Hybridity was verified using RAPD markers and morphological comparisons of hybrids and parents.

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(53) Freezing Tolerance of Twenty-Seven Saltgrass Ecotypes Was Similar in 2004 and 2005

HortScience ◽

10.21273/hortsci.41.4.1038a ◽

2006 ◽

Vol 41 (4) ◽

pp. 1038A-1038

Author(s):

Hrvoje Rukavina ◽

Harrison Hughes ◽

Yaling Qian

Keyword(s):

Abiotic Stress ◽

Geographical Distribution ◽

Freezing Tolerance ◽

Cold Hardiness ◽

Warm Season ◽

Northern Areas ◽

Fort Collins ◽

Freezing Test ◽

Cold Hardy ◽

Collection Sites

Freezing is the major abiotic stress that limits geographical distribution of warm-season turfgrasses. Prior studies have indicated variation in freezing tolerance in saltgrass clones. Therefore, this 2-year study examined the freezing tolerance of 27 saltgrass clones as related to collection sites in three zones of cold hardiness. Furthermore, these clones were evaluated for time of leaf browning in the fall with the intent to determine if there was a correlation between this trait and freezing tolerance. Rhizomes were sampled during 2004 and 2005 midwinters from clones established in Fort Collins, Colo., and then subjected to a freezing test. Saltgrass freezing tolerance was highly influenced by the climatic zone of clone origin in both years of the experiment. Clones with greater freezing tolerance turned brown earlier in fall in both seasons. Ranking of zones for the average LT50 was: zone 4 (–17.2 °C) < zone 5 (–14.4 °C) < zone 6 (–11.1 °C) in 2004 and zone 4 (–18.3 °C) < zone 5 (–15.7 °C) < zone 6 (–13.1 °C) in 2005. Clones from northern areas tolerated lower freezing temperatures better overall. This confirmed that freezing tolerance is inherited. Large intraspecific variation in freezing tolerance may be effectively used in developing cold-hardy cultivars.

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Freezing Tolerance of 27 Saltgrass Ecotypes from Three Cold Hardiness Zones

HortScience ◽

10.21273/hortsci.42.1.157 ◽

2007 ◽

Vol 42 (1) ◽

pp. 157-160 ◽

Cited By ~ 8

Author(s):

Hrvoje Rukavina ◽

Harrison G. Hughes ◽

Yaling Qian

Keyword(s):

Abiotic Stress ◽

Freezing Tolerance ◽

Cold Hardiness ◽

Warm Season ◽

Lethal Temperature ◽

Northern Areas ◽

Fort Collins ◽

Freezing Test ◽

Cold Hardy ◽

Collection Sites

Freezing is the major abiotic stress that limits geographic distribution of warm season turfgrasses. Prior studies have indicated variation in freezing tolerance in saltgrass clones. Therefore, this study examined freezing tolerance of 27 saltgrass clones as related to collection sites in three zones of cold hardiness. Furthermore, these clones were evaluated for time of leaf browning in the fall with the intent to determine if there was a correlation between this trait and freezing tolerance. Rhizomes were sampled during 2004 and 2005 midwinters from clones established in Fort Collins, Colo., and then subjected to a freezing test in a programmable freezer. Saltgrass freezing tolerance was highly influenced by the climatic zone of clone origin in both years of the experiment. Clones with greater freezing tolerance turned brown earlier in fall in both seasons. Ranking of zones for the average LT50 (lethal temperature at which 50% of rhizomes died) was: zone 4, most northern (−17.2 °C) < zone 5 (−14.4 °C), < zone 6, most southern (−11.1 °C) in 2004, and zone 4 (−18.3 °C), < zone 5 (−15.7 °C) < zone 6 (−13.1 °C) in 2005. Clones from northern areas tolerated lower freezing temperatures overall. This likely indicates that freezing tolerance is inherited. Large intraspecific variation in freezing tolerance may be effectively used in developing cold hardy cultivars.

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DEVELOPMENT OF A WHITE-FLOWERED, COLD-HARDY ALSTROEMERIA

HortScience ◽

10.21273/hortsci.41.3.491b ◽

2006 ◽

Vol 41 (3) ◽

pp. 491B-491

Author(s):

Elizabeth Kollman ◽

Mark Bridgen

Keyword(s):

United States ◽

Cold Hardiness ◽

Flower Color ◽

The United States ◽

Ms Medium ◽

Ploidy Levels ◽

Reciprocal Crosses ◽

Hand Pollination ◽

Cold Hardy

Alstroemeria, the Inca lily or lily-of-the-Incas, is becoming a popular garden plant in the United States. In past years, the primary interest in Alstroemeria has been for its cut flowers. However, recent cold-hardy introductions (USDA hardiness zone 5) have expanded the interest of this colorful plant as a garden perennial throughout the U.S. Previously, garden interests were restricted to warmer zones in the southern United States where Alstroemeria could over-winter. This research describes a breeding procedure which has been used with the objective to develop a cold-hardy, white flowered Alstroemeria. The interspecific hybrids were bred with the use of in ovulo embryo rescue. Reciprocal crosses were made between several white-flowered cultivars and the cold hardy Chilean species, Alstroemeria aurea during the summers of 2004 and 2005. Ovaries were collected 10–23 days after hand pollination and their ovules were aseptically excised. Ovules were placed in vitro on 25% Murashige and Skoog (MS) medium under dark conditions until germination. Three weeks after germination they were then placed on 100% MS medium, and subcultured every three to four weeks thereafter until they were large enough for rooting. After rooting and acclimation, plants were transferred to the greenhouse. Successful hybrids that were produced in 2004 were evaluated under greenhouse and field trials during 2005. Data on the flower color for each of the hybrids were recorded, as well as certain morphological characteristics that can indicate cold-hardiness. Hybrid plants are being overwintered outside in Ithaca, N.Y. (USDA zone 5), and Riverhead, N.Y. (USDA zone 7), during the next several years for a more accurate assessment of cold-hardiness. Self pollinations and reciprocal crosses with the white-flowered parent were performed on the F1 generation in the summer and fall of 2005 in order to determine segregating characteristics. Few ovules were obtained from F1 generation crosses. Successful F2generation plants are being grown in vitro and will be transferred to the greenhouse where flower color will be noted. Root squashes and pollen staining were completed to determine ploidy levels and assess male sterility of the F1 generation.

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(436) Comparative Cold Hardiness and Freezing Behavior of Leaves, Buds, and Flowers in Selected Woody Plants in Northern Latitudes

HortScience ◽

10.21273/hortsci.40.4.1077a ◽

2005 ◽

Vol 40 (4) ◽

pp. 1077A-1077

Author(s):

A.M. Shirazi ◽

M.V. Thierry

Keyword(s):

Woody Plants ◽

Cold Hardiness ◽

Extreme Temperature ◽

Freezing Stress ◽

Ion Leakage ◽

Spring Frost ◽

Cornus Mas ◽

Northern Latitudes ◽

Cold Hardy ◽

Eventual Death

It is not well known how cold-hardy new buds and emerging leaves or flowers are during spring. Extreme temperature fluctuations that sometimes bring early frost in spring (April–May) are very common in northern latitudes and cause severe damage to emerging leaves and flowers. Even though most woody plants can tolerate frost in spring, others show early tissue damage and can fully recover. There are some trees, e.g., Japanese maples (Acer palmatum) that when leaves are damaged due to spring frost, the results include severe dieback and eventual death. We tested new flowers and leaves of four crabapples: Malus ×micromalus, M. sargentii, `Mary Potter', and M. hupehensis, after budbreak for 3 years using electrical conductivity (EC) and differential thermal analysis (DTA) in spring: May 1997, Apr. 1998, and Apr. 2000, at The Morton Arboretum. Both flowers and leaves can tolerate from –6 to –12 °C and we observed higher ion leakage in leaves than flowers. The high temperature exotherm (HTE) of flowers were –8 to –10 °C in April. In a companion study, testing other species that had premature budbreak due to “near lethal” (sublethal) freezing stress in Jan. 2001, the following HTE were observed: Cornelian cherry (Cornus mas) flower (about –7.5 °C), Spindle trees leaves (about –6 °C), Judd's viburnum (Viburnum ×juddii) (about –8 °C), Brevipetala witch-hazel (Hamamelis mollis`Brevipetala') flower (about –5 °C), redbud (Cercis candensis) flower (about –9 °C), flowering quince (Chaenomeles ×superba) flower (–8 °C). Multiple LTE at –13, –18, –22, and –27 °C were observed for Judd's viburnum. This information could be useful for selection and breeding of woody plants.

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Freezing Tolerance of Saltgrass (Distichlis spicata) Ecotypes

HortScience ◽

10.21273/hortsci.40.4.1106d ◽

2005 ◽

Vol 40 (4) ◽

pp. 1106D-1106

Author(s):

Hrvoje Rukavina ◽

Harrison Hughes ◽

Yaling Qian

Keyword(s):

Freezing Tolerance ◽

Cold Hardiness ◽

Selection Criterion ◽

Least Square ◽

State University ◽

Colorado State University ◽

Color Retention ◽

Fort Collins ◽

Freezing Test ◽

Cold Hardy

Efforts are ongoing at Colorado State University to develop turf-type saltgrass cultivars. Prior freezing studies have indicated variation in freezing tolerance in saltgrass lines. Therefore, this study was made to examine relative freezing tolerance of 27 saltgrass clones as related to collection sites in three zones of cold hardiness. Furthermore, these lines were evaluated for fall color retention with the intent to determine if there is a correlation with fall color and freezing tolerance. Saltgrass rhizomes were sampled in mid-winter 2004 from lines established in Fort Collins, Colo., and then subjected to a laboratory-freezing test. Saltgrass freezing tolerance was highly influenced by climate zones of clones' origin (P < 0.01) and genotypes within zones (P < 0.01). There was a high negative correlation between color retention in the fall and freezing tolerance (P < 0.01). Average freezing tolerance of saltgrass clones within zones of origin significantly differed among zones. Ranking of zones for least square mean LT50 (OC) was: zone 4 (–17.2) < zone 5 (-14.4) < zone 6 (–11.1). LT50 values in zone 4 ranged from –17.8 (accession 72) to –17.0 (accession 87). Clones in zone 5 showed LT50 values from –17.8 (accession A29) to –11.9 (accession A137). Zone 6 clones had LT50 values that ranged from –9.5 (accession C92) to –12.6 (accession C12). Large intraspecific variation in freezing tolerance may be effectively used in new cold hardy cultivar development. Environmental adaptation inherited by origin of clone is useful in defining clones' adaptation range and may along with fall color retention serve as a selection criterion in saltgrass cold hardiness improvement.

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Relative Resistance or Susceptibility of Landscape-suitable Elms (Ulmus spp.) to Multiple Insect Pests

Arboriculture & Urban Forestry ◽

10.48044/jauf.2013.031 ◽

2013 ◽

Vol 39 (5) ◽

Author(s):

Daniel Potter ◽

Carl Redmond

Keyword(s):

Insect Resistance ◽

Insect Pests ◽

Late Summer ◽

The United States ◽

Scale Insects ◽

Dutch Elm Disease ◽

Urban Landscapes ◽

Japanese Beetle ◽

Relative Resistance ◽

Cooperative Project

The National Elm Trial is a cooperative project to assess landscape suitability of Dutch elm disease-resistant elms (Ulmus spp.) in various regions of the United States. Researchers evaluated 20 cultivars of American, Asian, and hybrid elms for relative resistance or susceptibility to multiple insect pests in central Kentucky over seven years. Ratings for Japanese beetle, European elm flea weevil (EEFW), and several other pests were previously published. This paper reports data for seven additional pests, including honeydew-excreting scale insects (Parthenolecanium corni, Eriococcus spuria, and Pulvinaria innumerabilis), leaf-distorting woolly elm and woolly apple aphids (Eriosoma spp.), elm cockscomb gall aphid (Colopha ulmicola), and an invasive weevil (Oedophrys hilleri) not previously known to damage elms. Rankings for all 12 of the monitored pests are summarized. Most U. americana cultivars were relatively susceptible to the scale insects and likewise, Eriosoma spp. and C. ulmicola only infested the American elms. O. hilleri is a new state record for Kentucky. Its adults, active in mid- to late summer, chewed notches in edges of leaves. Cultivars of the Asian species U. parvifolia and U. propinqua, including ‘Athena Classic Lacebark’, ‘Everclear Lacebark’, ‘Emer II Allee’, and ‘Emerald Sunshine’ were top-rated for insect resistance. They were nearly pest-free except for foliar damage by EEFW, to which nearly all elms were susceptible. Insect resistance should be considered when re-introducing elms to urban landscapes. The data may help city foresters, landscapers, and others re-introducing elms to urban landscapes to select relatively pest-free cultivars requiring minimal inputs for insect control.

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Cold hardiness of tree-hole mosquitoes in the Great Lakes region of the United States

Canadian Journal of Zoology ◽

10.1139/z90-195 ◽

1990 ◽

Vol 68 (6) ◽

pp. 1307-1314 ◽

Cited By ~ 5

Author(s):

Robert S. Copeland ◽

George B. Craig Jr.

Keyword(s):

Cold Hardiness ◽

Laboratory Experiments ◽

The United States ◽

Great Lakes Region ◽

Aquatic Animal ◽

Larval Stages ◽

Tree Hole ◽

Reproductive Capability ◽

Freeze Tolerant ◽

Cold Hardy

We examined cold hardiness of the overwintering stages of five species of North American tree-hole mosquitoes through laboratory experiments and field observations. Among the species that overwinter as larvae, fall-collected individuals were freeze tolerant, whereas all summer-collected larvae were killed by freezing. Cold hardiness varied among species and among larval stages within species. The order of diminishing cold tolerance was Orthopodmyia alba, Anopheles barberi, and Orthopodomyia signifera. Some O. alba larvae survived freezing at −25 °C, the lowest temperature reported to be survived by an aquatic animal in ice. Prolonged (up to 16 days) and multiple (four) exposures to −15 °C had no effect on survival of O. alba third-instar larvae, but increased mortality of second instars of O. alba and A. barberi. Species were more tolerant of cold when frozen in rot-hole water in which they are commonly found in nature than in "pan" water in which they rarely occur. Both photoperiodically induced dormancy and prefreezing exposure to low temperature were necessary for the establishment of cold hardiness in laboratory-reared A. barberi. Eggs of Aedes triseriatus and Aedes hendersoni were more cold hardy than larvae of Orthopodomyia and Anopheles. Neither preconditioning to cold nor dormancy was necessary for survival at −15 °C for 24 h. Females that had survived temperatures to −25 °C as eggs showed no impairment of reproductive capability.

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Seasonal Cold Hardiness Differences of Three Woody Plant Taxa during the Production Stage and as Established Landscape Plants

Journal of Environmental Horticulture ◽

10.24266/0738-2898-12.1.33 ◽

1994 ◽

Vol 12 (1) ◽

pp. 33-35

Author(s):

Orville M. Lindstrom ◽

Michael A. Dirr

Keyword(s):

Cold Hardiness ◽

Woody Plant ◽

Production Stage ◽

Ulmus Parvifolia ◽

Landscape Plants ◽

Nursery Production ◽

Cold Hardy

Abstract Seasonal cold hardiness levels of Crape myrtle (Lagerstroemia L. ‘Natchez’), Leyland cypress [× Cupressocyparis leylandii (A.B. Jacks. and Dallim.) Dallim. and A.B. Jacks.] ‘Haggerston Gray’ and Lacebark elm (Ulmus parvifolia Jacq. Allee™) were determined for nursery production and established landscape plants grown at the same location. Differences in cold hardiness between the growth treatments were taxon specific. During October, November and December, nursery-grown crape myrtle plants were up to 11°C (20°F) less cold hardy than those established in the landscape. Differences in Leyland cypress cold hardiness were detected, but were not as great as in crape myrtle. During October, November and December newly transplanted Leyland cypresses were from 3 to 6°C (5 to 11°F) less cold hardy compared to established landscape plants. Differences occurred between nursery production and established landscape plants of lacebark elm in January and February.

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