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- Author or Editor: William E. Roberson x
Field grown `Mr. Lincoln' rose plants were dug and wrapped in plastic to reduce moisture loss during transport to the lab. Plants were then pruned, weighed, and returned to the plastic cover. After recording initial weights, plants were allowed to dry for 0, 1, 4, 7, or 24 hours at 16°C. Plants were then oven dried, potted, or soaked in water for 20 hours before potting for each drying time treatment. The potted plants were forced to first flower in a glasshouse at which time growth measurements were made. Undried plants had a moisture content of 48%. Seven hours drying reduced moisture content to 41%, but had no effect on growth or flowering. The 24 hour drying time resulted in a plant moisture content of 33%, a plant loss of 44%, and delayed growth initiation and flowering by up to 15 days compared to undried controls. Soaking after 24 hours drying increased plant survival from 38 to 75%. Plants that survived the excessive drying produced flowering growth comparable to plants with a moisture content of > 40%. A critical moisture level for rose plant survival was found to be between 33 and 41%.
The East Texas Bedding Plant Pack and Garden Performance Trials are performed as an interaction between the plant material source companies, the plant producer companies, volunteers, and retail consumers. The Overton Trial Site is located near a concentration of bedding plant growers ($80 million annual wholesale value) which is part of the close to $500 million in ornamental plant production in northeast and north central Texas, about half of the state industry value. The spring and fall trials consist of two phases. The greenhouse phase consists of assessing production performance for use by the crop production industry. Crops are usually finished in packs (36 cells per flat), but larger size containers are used as needed according to species. Height control is a major issue and specific issues have been addressed. This is one way that publishable data can be generated by these trials. The garden phase consists of assessing garden performance in a replicated field setting at the Overton site. Garden performance is also assessed for many of the entries at sites at the Dallas Arboretum and Botanical Garden and the Texas A&M Univ. Agricultural Research and Extension Center at Dallas. An integral part of the trials are the volunteers who, as members of the Smith County Master Gardener Association, donate hundreds of hours of labor to the seeding, transplanting, and garden establishment phases of the trials. In addition, a web site has been initiated as the only practical way to share the data and hundreds of images that are generated each trial season.
The East Texas Bedding Plant Pack and Garden Performance Trials began several years ago at the Texas A&M University Agricultural Research and Extension Center at Overton (Overton Center) with the goal of providing information on greenhouse and field performance of bedding plant varieties to the local bedding plant industry and consumers of these products. The program began with local trials that have now expanded in scope with the Smith County Master Gardeners Association playing an integral role in performing the trials. Entries are received from most of the major ornamental seed companies doing business in the United States giving the regional industry access to the only comprehensive greenhouse performance trials in this part of the country. Performance evaluation data is important to this industry since it has a wholesale value of over $500 million in the northeast Texas region, of which over $100 million is bedding plant production. The field performance trials are now replicated at the Overton Center, the Dallas Arboretum and Botanical Garden (Dallas Arboretum) and the Texas A&M University Agricultural Research and Extension Center at Dallas (Dallas Center), giving over 5 million consumers in the northeast Texas region the opportunity to see how promising new plants from all over the world perform in the local climate. Plants that grow well in this climate have the potential to reduce inputs needed for production and use in the home or commercial landscape. Many of the top performing varieties from the bedding plant trials are also chosen to be part of the Coordinated Education and Marketing Assistance Program (CEMAP), a statewide testing program headquartered at the Dallas Center in which entries vie for designation as Texas Superstar plants. The comprehensive benefit of the East Texas Bedding Plant Pack and Garden Performance Trials is the link between the rural bedding plant producers and the urban consumers which serves as a basis for improving the quality of life for the citizens of Texas.
To determine the efficacy of cyproconazole for control of black spot [Marssonina rosae (Lib.) Lind] when applied as a drench, treatments of 0, 32.5, 65, 97.5 and 130 g a.i./ha were initiated 9 May 1994 on individual Rosa `Peace' plants in a randomized complete-block design. Treatments were applied once per month until 18 Oct. 1994. Data were taken in July, Sept., and Nov. 1994 when separate disease and defoliation ratings were assigned. By July, the controls were heavily infected; the higher treatment rates resulted in significant control. By September, the disease and defoliation ratings exhibited a linear response with cyproconazole rate, with the highest treatment rate giving the best control. The relationship between disease and defoliation ratings and treatment rate remained the same in November, although there was increased disease incidence overall. No phytotoxicity was observed. These results indicate that soil applied treatments of cyproconazole can control black spot effectively on roses.
The effect of exogenous ethylene was investigated on single-stemmed plants of Rosa L. `RUIdodo', `RUIrosora', `RUIjef', `MEIferjac', `MEIshulo', `MEIghivon' and `MEIgagul' grown in controlled environment growth chambers simulating summer-like and winter-like conditions. When the flower on each plant reached developmental stage 2 (showing color, calyx reflexing, no petals reflexed), the plants were placed for 18 h in plexiglass chambers with ethylene at 0, 0.1, 0.5, 1.0 and 5.0 μL·L-1 under a simulated interior environment at 21 °C with 14 μmol·m-2·s-1 fluorescent light. Under the same interior environment, the plants were kept for postharvest evaluation. Response to ethylene of all cultivars was not affected by the difference in growing conditions. As shown previously by other authors, however, the ethylene reduced flower longevity. Treatment with 0.1 μL·L-1 of ethylene reduced flower longevity by 1 day in comparison to the control (0 μL·L-1). The ethylene concentrations of 1.0 μL·L-1 and 5.0 μL·L-1 reduced flower longevity by 3 days. Regardless of ethylene concentration or growing conditions, `RUIjef' and `MEIferjac' exhibited the longest flower longevity and `MEIghivon' and `MEIgagul' the shortest flower longevity. All cultivars, except `RUIrosora', exhibited the longest flower longevity under summer-like vs. winter-like conditions, with the difference ranging from 1.5 to 5 days. `RUIrosora' exhibited similar flower longevity regardless of growing conditions. Differences in flower longevity in response to seasonal growing conditions have been found by us and other authors, but the cultivars used in this study have not been previously studied. This difference in flower longevity as a response to growing conditions cannot be explained by differences in response to ethylene so that other factors must be involved.
Plants of field grown rose cultivars Blaze, Gold Glow, Queen Elizabeth, Mr. Lincoln, Montezuma, Don Juan, Chicago Peace, and Pink Peace endured two major freezes. Temperatures fell to -13°C on 16 December 1989 and as low as -20°C during an extended period from 17 to 28 December 1989 when the highest temperature reached was 5°. Grade 1 plants of each cultivar were harvested on 5 January 1990. At harvest, discoloration of the pith, xylem ray parenchyma and bud union tissue was assessed. Additional plants were then potted and forced in a glasshouse at 15° night temperalure with venting at 21° during the day. At the end of the initial flush of growth, which was defined as either the opening of the first flower or the determination that all new shoots were blind, new growth was rated and measured. Blaze exhibited minimal damage with only slight pith discoloration. The total number of flowering shoots (TNFS) for Blaze was 5.5 per plant which is an expected number from a grade 1 plant. Of the other cultivars. Gold Glow and Pink Peace exhibited pith, xylem, and bud union damage with up to 50% cane dieback, but produced flowering shoots from the graft union. However, only half the expected TNFS per plant were produced. The remaining cultivars also exhibited higher damage levels than Blaze which resulted in reduced shoot numbers and flowering. Only Blaze plants received an acceptable plant marketability rating.
A strain of Rhizoctonia solani was isolated from wax begonia (Begonia Semperflorens-Cultorum hybrids) plants in garden evaluation trial plots. This strain was then used to test for disease tolerance in a controlled environment experiment. Inoculated plants of 12 cultivars were evaluated for disease development and the area under the disease progress curve was calculated. No plants were disease free, but `Stara White', `Stara Pink', and three colors from the Party series exhibited greater disease tolerance than `Ambassador Coral', `Ambassador Deep Rose', and two experimental varieties. `Stara White', `Party Pink Bronze Leaf', and `Party White Bronze Leaf' were more tolerant than `Cocktail Vodka', an industry standard. When the same cultivars were grown in field garden evaluation plots, `Cocktail Vodka', four colors from the Stara series, and three colors from the Party series exhibited superior garden performance and flowering ratings to `Ambassador Coral' and an experimental `Rose' cultivar. For most cultivars, garden performance was correlated to disease tolerance. However, `Cocktail Vodka' exhibited good garden performance despite having a high level of disease in the inoculation experiment, indicating that other factors may be involved in determining garden performance.