Search Results

You are looking at 1 - 10 of 29 items for

  • Author or Editor: Orville M. Lindstrom x
Clear All Modify Search
Free access

Orville M. Lindstrom

Leyland cypress [×Cupressocyparis leylandii (A.B. Jacks. and Dallim.) Dallim. and A.B. Jacks.] plants were transplanted into the field monthly from Aug. 1989 through Mar. 1990, and laboratory cold-hardiness estimates of these transplants were obtained monthly for two winter seasons. Cold hardiness estimates obtained in Dec. 1989 and Jan. 1990 revealed that the Nov. and Dec. 1989 transplants were 6C less cold-hardy than those transplanted into the field earlier in the year. There was little difference in cold hardiness due to transplant date during Feb., Mar., and Apr. 1990. In the second year of the study, on the same transplants, cold hardiness varied among transplanting dates. In Dec. 1990 and Jan. 1991, those transplanted in Jan.-Mar. 1990 were up to 9C less cold-hardy than those transplanted earlier in the season. However, in Mar. and Apr. 1991, those transplanted in Jan.-Mar. 1990 were equally or more cold-hardy than those transplanted earlier in the season. Transplanting Leyland cypress into the field in August to November appears to be the best time to ensure development of cold hardiness in early winter, whereas January to March planting appears to promote greater cold hardiness in the spring months.

Free access

Orville M. Lindstrom

Whole, half, and quarter leaves and leaf disks were used to make laboratory estimations of the cold hardiness of Magnolia grandiflora. The effects of ice nucleation temperatures, length of exposure to nucleating temperatures, rates of temperature drop, thawing regimes, and methods of injury analysis were investigated for each leaf type in the fall and midwinter. In general, whole and half leaves responded more consistently to freezing tests than did quarter leaves and leaf disks. The most critical factors in the freezing procedure are the temperature at which the samples are nucleated with ice crystals and the regime in which the samples are warmed. These data suggest that whole and half leaves can effectively be used to reliably predict the cold hardiness of southern magnolia leaves.

Free access

Orville M. Lindstrom

The cold hardiness of seven deciduous hardwoods, red maple (Acer rubrum L.), white oak, (Quercus alba L.), green ash (Fraxinus pennsylvanica Marsh.), sweetgum (Liguidambar stryaciflua L.), sugar maple (Acer saccharum Marsh.), river birch (Betula nigra L.) and black cherry (Prunus serotina Ehrh.) were evaluated weekly during the fall, winter and spring for three consecutive years. All trees evaluated were established (20-40 years old) and locatd on the Georgia Station Griffin, GA. Each species developed a maximum cold hardiness of at least -30 C by mid-January or early February each season. Response to temperature fluctuations varied with species. Red maple, for example, lost less cold hardiness due to warm mid-winter temperatures than the other species tested, while white oak tended to respond more quickly to the temperature fluctuations. Data will be presented comparing the response of cold hardiness to mid-winter temperature fluctuations for each species for the three year period.

Free access

Tomasz Anisko and Orville M. Lindstrom

The purpose of the present study was to determine whether water stress affects tolerance of Rhododendron L. `Catawbiense Boursault' to rapid freezing. Tolerance to freezing at cooling rates of 2 or 6C/hour in stems and leaves of plants subjected to continuous and periodic water deficit stresses was examined. Under continuous stress treatments, water content of the growing medium was maintained in a range of 0.60 to 0.75, 0.45 to 0.60, or 0.30 to 0.45 m3·m–3 between 24 Aug. 1992 and 11 Feb. 1994. Under periodic stress treatments, water content of the growing medium was maintained near field capacity, i.e., 0.6 to 0.8 m3·m–3, for the duration of the study or plants were subjected to the periodic stress at various times between 15 July and 19 Feb. during 2 years. Watering of water-stressed plants was delayed until water content reached below 0.4 m3·m–3, and then was resumed to maintain water content in the range of 0.3 to 0.4 m3·m–3. Cold hardiness was evaluated in the laboratory with freeze tolerance tests on detached leaves and stem sections. In most cases, cooling at 6C/hour caused injury at higher temperature than cooling at 2C/hour. The difference in lethal temperature between the two cooling rates depended on the level of the plant's cold hardiness. In plants cold hardy to about –25C, freezing at 6C/hour caused injury at a temperature ≈3C higher than freezing at 2C/hour. The effect of cooling rate was not evident in plants cold hardy to about –18C. Subjecting plants to continuous or periodic water stress did not have an effect on this relationship.

Free access

Tomasz Anisko and Orville M. Lindstrom

The primary cause of losses in evergreen azaleas injured by early freeze is bark split on lower stems. Delayed acclimation in the fall is thought to permit this injury. We examined whether reduced water supply affects acclimation of Rhododendron L. `Coral Bell', `Hinodegiri', and `Red Ruffle'. Containerized plants were grown under four watering regimes and placed outdoors or in the greenhouse. The water content of the growing medium was maintained at either 0.3 to 0.4 or 0.5 to 0.6 m3·m-3 from 16 June to 30 Aug. 1993, when half of the plants under each of these regimes was switched to the other watering regime. Freeze tests were conducted on 30 Aug. and 9 (let. Injury to leaves, and lower, middle, and upper stems was evaluated visually. Acclimation of leaves and upper stems before the August test, in most cases, was not stimulated by reduced water content, while the response of lower and middle stems was cultivar- and location-specific. The lower water content treatment after 30 Aug. generally increased freeze tolerance of all plant parts regardless of the previous watering regime. The higher water content treatment after 30 Aug. either prevented or delayed acclimation. This study demonstrated that the reduced water supply provided a feasible means of promoting acclimation of evergreen azaleas in late summer.

Free access

Tomasz Anisko and Orville M. Lindstrom

The effect of water stress imposed at three dates in late summer and early fall on cold hardiness was examined in Rhododendron L. `Coral Bell', `Hinodegiri', and `Red Ruffle'. The persistence of the water stress-induced cold hardiness was also examined following plant recovery from the stress. Container-grown plants were exposed to three weeks of reduced water supply starting 8 Aug., 29 Aug., or 19 Sept., while control plants were well watered. Cold hardiness of leaves, lower, middle, and upper stems was evaluated with laboratory freeze tests. Reduced water supply independent of time initiated increased cold hardiness by 1 to 4C in the majority of the tested plant parts in the three cultivars. Cold hardiness of all plant parts tested strongly depended on the current water status of the plants as indicated by the stem water potential. In most cases, 3 weeks after rewatering, the cold hardiness of previously water stressed plants did not differ from that of nonstressed plants.

Free access

Tomasz Anisko and Orville M. Lindstrom

Water status is known to have an impact on cold hardiness of plants. Cold hardiness of `Catawbiense Boursault' rhododendron was examined under continuous and periodic water stress. Under continuous stress, water content of growing medium was maintained at 0.6 to 0.75, 0.45 to 0.6, or 0.3 to 0.45 m3·m-3. Under periodic stress, water content was either maintained between 0.6 to 0.8 m3·m-3 or plants were subjected to drought episodes at various times in late summer, autumn, and early winter. During a drought episode, watering was delayed until water content was below 0.4 m3·m-3. Watering then resumed and water content was maintained between 0.3 to 0.4 m3·m-3. Cold hardiness was evaluated on detached leaves and stem sections. The effect of continuous water stress depended on its severity and duration. Moderate stress did not increase cold hardiness compared to well watered plants during the first winter, but it did so when continued into the second winter. More severe stress increased cold hardiness during the first winter, but it decreased cold hardiness during the subsequent winter. The effect of periodic water stress depended on the timing of application. During initial and final stages of acclimation, cold hardiness increased in response to water stress less than during the intermediate stages. Water-stress-induced cold hardiness gradually decreased after rewatering.

Free access

Tomasz Anisko and Orville M. Lindstrom

The effect of water stress on cold hardiness was examined in evergreen azaleas, `Coral Bell' (CB), `Hinodegiri' (HD), and `Red Ruffle' (RR). Plants were well-watered between 8 Aug. and 1 Nov. (wet) or were subjected to 3 weeks of reduced water supply starting on one of three dates, 1 Aug. (dry 1), 29 Aug. (dry 2), and 19 Sept. (dry 3). Cold hardiness of leaves and lower, middle, and upper stems was tested on 29 Aug., 19 Sept., 10 Oct., 1 Nov. By the end of each 3-week period, water potential of water stressed plants reached –1.5 to –1.8 MPa compared to around –0.8 MPa of well-watered plants. Reducing the water supply significantly increased cold hardiness of all tested plant parts in all cultivars regardless of timing of watering reduction, with two exceptions, CB middle stems on 29 Aug. and HD leaves on 19 Oct. Three weeks after rewatering cold hardiness of water-stressed plants did not differ significantly from well-watered plants, except for HD plants under dry three treatment, which continued to be 1.0 (middle stems) to 4.3 (upper stems) more cold hardy.

Free access

Tomasz Anisko and Orville M. Lindstrom

Three cultivars of evergreen azaleas, `Coral Bell', `Hinodegiri', and `Red Ruffle', were grown under four watering regimes in containers and placed outdoors or in the greenhouse. The water content of the growing medium was maintained at either 0.3 to 0.4 or 0.5 to 0.6 m3m-3 from June 16 to August 30, when half of the plants under each of these regime was switched to the other watering regime. Freeze tests were conducted on August 30 and October 9, 1993. Injury to leaves, lower, middle, and upper stems was evaluated visually. Acclimation of leaves and upper stems prior to the August test, in most cases, was not stimulated by reduced water content, while the response of lower and middle stems was cultivar and location specific. The lower water content treatment after August 30 generally increased freeze tolerance of all plant parts regardless of the previous watering regime. The higher water content treatment after August 30 either prevented or delayed acclimation.

Free access

Orville M. Lindstrom and Malgorzata A. Florkowska

To date, few summer and fall flowering azaleas exist. Recently, Rhododendron oldhamii, a summer-flowering species, was hybridized with several commercial hybrids. These crosses produced various sizes and colors of flowers that bloom throughout the summer until frost, and again in the spring. However, the cold hardiness level of these azaleas is unknown. Therefore, we evaluated their cold hardiness during several months of the fall and winter. Laboratory cold hardiness tests revealed that there was a range of cold hardiness levels among the new hybrids. `Fashion' and hybrids 02003 and 4003 tended to acclimate earlier than the others, maintain a good level of midwinter cold hardiness, and retain their hardiness into the early spring. Hybrid 15001 acclimated early and had good midwinter cold hardiness, but lost its cold hardiness in the late winter, while 04003 and 09004 acclimated late in the fall and did not attain a high level of cold hardiness in the winter. `Lee's Select' and hybrid 08002 seemed to fall between the groups previously mentioned showing intermediate cold hardiness throughout the winter season. The laboratory cold hardiness results were similar with field observations.