Distinct differences in freezing tolerance among a cold-hardy wild rose species Rosa fedtschenkoana Regel., a garden rose, `Jack Frost', and their hybrid could be detected under laboratory conditions using 2-cm-long shoot segments with buds. The garden rose did not survive - SC, but the cold-hardy species survived freezing to -10C and the hybrid to –5C. One week of acclimation at 4C was adequate for R. fedtschenkoana; longer periods did not improve the rate of survival. Immersing tissue in 5%, 10%, or 20% sucrose during acclimation improved the rate of survival of R. fedtschenkoana but not of `Jack Frost'. Applications to rose breeding are discussed.
During the past three decades, ecologically friendly landscaping has strived to implement plants that not only require less water and other inputs but also create esthetic value and biodiversity in gardens ( Brzuszek et al. 2010 ; Potts et
Roses are likely the most popular garden plant in the United States, and cultivars are also used as landscape plant materials. Three herbicide trials with two main objectives were conducted with rose plants. The first objective was to evaluate injury to the roses when over-sprayed at various stages of growth. The second objective was to evaluate the efficacy of the herbicides. All herbicides were used at label rates and applied over the top of rose plants. In the first trial, the pre-emergent herbicides pendimethalin, oryzalin, trifluralin, metolachlor, napropamide, and oxyfluorfen were applied to plots containing dormant roses with ≈1-cm shoots just pushing. Evaluations of shoot length taken over the next 6 weeks showed no differences in growth of rose plants, but weed populations were reduced. In the second trial, five post-emergent herbicides were applied to plots containing dormant roses. Herbicides evaluated included the grass herbicides fluazifop-p-butyl, sethoxydim, and clethodim. The nonselective herbicide glyphosate was included in the trial, as was a combination herbicide containing 2,4-D, mecoprop, and dicamba. There was no visible injury to rose plants until 6 weeks after treatment. At that time, roses treated with glyphosate had shorter shoots. Recovery from glyphosate appeared more rapidly than recovery from the combination herbicide. Weed control varied with each herbicide. The third trial evaluated the same five herbicides for control of bermudagrass in late spring. Injury to roses was noted immediately from the combination herbicide and glyphosate. All the grass herbicides and glyphosate were effective in controlling bermudagrass.
Cleome hassleriana is an ornamental garden plant introduced from South America and naturalized in eastern United States with tendencies to reseed primarily in gardens. The objectives of this research were to determine (1) if C. hassleriana cultivars can germinate in Minnesota prairies and roadsides, (2) if germination in cultivated environments reflect germination in non-cultivated environments, and (3) if there are differences among cultivars across environments, with some cultivars germinating well in cultivated habitats and poorly in non-cultivated habitats. In June 2003, 135 seeds from each of four cultivars (Queen Rose, Queen White, Sparkler Rose and Sparkler White) were planted in each of 4 gardens and 8 non-cultivated habitats (4 prairies and 4 roadsides). Germination and survival was recorded once weekly for four weeks. Cleome seeds germinated in Minnesota gardens, prairies and roadsides. By day 14, the proportion of germinated seedlings was significantly greater in gardens (30.5%) than in prairies (1.4%) and roadsides (0.9%). Sparklers had significantly greater germination than Queens in the prairies. The best performing cultivar in the garden (Queen White, 29%) was different than the best performing cultivar in the prairies and roadsides (Sparkler Rose, 1.4% and 1.2% respectively), suggesting that germination in non-cultivated habitats may not reflect germination in the field. Cultivars varied in their ability to germinate in cultivated and non-cultivated environments.
175 ORAL SESSION 51 (Abstr. 360-366) Rose and Tree Fruits (Citrus and Papaya): Breeding and Genetics
Abstract
‘Enric Bague’ is a new, compact rose with high yield of flowers, a prolonged flowering season (April-December outdoors and all year in the greenhouse for cut flowers; especially fine from November to May). ‘Enric Bague’ was developed especially for growing in small containers but is suitable for cultivation in the garden or greenhouse.
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.
Abstract
Present garden roses lack winter hardiness and are more or less susceptible to Blackspot. Winterhardy and disease resistant cultivars and species of Rosa are available but these have generally a short flowering season and they do not have the flower quality of present garden cultivars. Breeding programs were devised with diploid and tetraploid cultivars and species to obtain winterhardy, remontant roses with resistance to blackspot, Diplocarpon rosae Wolf., and to powdery mildew, Sphaerotheca pannosa Wall. ex. Fr./Lev. For the program at the diploid level, cultivars of R. rugosa Thunb. were used as source for hardiness and disease resistance and cultivars of R. chinensis Jacq. as source for the everblooming habit and flower quality. For the program at the tetraploid level, unnamed seedlings of different hybrid origin were used as source for hardiness and disease resistance and garden rose cultivars as source for the everblooming habit and flower quality. The desired results have been partially obtained from both breeding programs but the program with tetraploid roses produced the first tangible results.
Abstract
The pink-flowered ‘Aphrodite’ is the fourth U.S. National Arboretum triploid cultivar of Hibiscus syriacus L., commonly known as rose of sharon. In the past, rose of sharon, although it flowered heavily in early summer when few other shrubs bloom, produced abundant seed and, subsequently, weed seedlings in the garden. The development of nearly sterile triploid cultivars eliminated the source of weed seedlings and elevated the plant to an elite summer flowering shrub. Triploid cultivars previously introduced are ‘Diana’, NA 32224 (1), with pure white flowers; ‘Helene’, NA 41786 (2), with white flowers and a prominent dark red eye spot; and ‘Minerva’, NA 54984 (3), with lavender flowers.
Abstract
‘Charles Albanel’ and ‘Champlain’ roses are new releases which are valuable because of winterhardiness not found in present garden roses. ‘Charles Albanel’ is a R. rugosa Thunb. hybrid. It combines hardiness with a long flowering season and is highly resistant to both blackspot and mildew. The vigorous, low shrub makes it suitable as a ground cover. ‘Champlain’ is a complex hybrid of R. kordesii Wulff, R. laxa Retz., and R. spinosissima L. It combines hardiness with prolific flower production throughout the growing season, and is a medium high shrub with attractive red flowers.