Conifers represent a sizeable portion of nursery and landscape sales in the upper midwestern U.S. Several conifer species have been overplanted to the point where disease problems and insect pressures have developed. Although more than 40 true fir (Abies Mill.) exist throughout the northern hemisphere, use of firs in the landscape and Christmas tree industry has been limited to relatively few species. This is largely due to perceived intolerance of many site conditions. However, recent research suggests Abies are more tolerant of varying site conditions than originally thought. Successful introduction of new exotic fir species for landscape use will require a systematic approach to identify species that are adapted to environmental stresses. In this article we review the extent and nature of inter-specific variation among Abies species in traits commonly associated with tolerance of stresses found in the upper midwestern U.S. Specifically, we focus on cold hardiness, budbreak, photosynthetic gas exchange and water relations, and response to soil pH. It is important to match plants possessing necessary adaptive characteristics with the existing site conditions. Therefore, multiple screening factors should be met when identifying species or trees from different provenances for future introduction.
G.E. Jones and B.M. Cregg
M.W. Duck, B.M. Cregg, R.T. Fernandez, R.D. Heins, and F.F. Cardoso
Tabletop Christmas tree growers whose greenhouse-grown conifers have undesirable shoot growth may alleviate this problem by applying plant growth retardants (PGRs). Some of the most common PGRs in the horticulture industry were evaluated to determine their effectiveness in controlling plant height: ancymidol at 100 μL·L-1 (ppm), daminozide at 5000 μL·L-1, paclobutrazol at 60 μL·L-1, chlormequat at 1500 μL·L-1, uniconazole at 15 μL·L-1, and ethephon at 500 μL·L-1 compared to a nontreated control. The following conifer species were used: colorado blue spruce (Picea pungens), black hills spruce (P. glauca var. densata), serbian spruce (P. omorika), noble fir (Abies procera), grand fir (A. grandis), fraser fir (A. fraseri), concolor fir (A. concolor), arborvitae (Thuja occidentalis), port orford cedar (Chamaecyparis lawsoniana), and douglas-fir (Pseudotsuga menziesii). Chlormequat was the only PGR that caused phytotoxicity and damage to the foliage was minimal. Noble fir, douglas-fir, colorado blue spruce, and arborvitae were unaffected by any PGR treatment. Daminozide reduced growth of port orford cedar and concolor fir; uniconazole reduced growth of black hills spruce and serbian spruce; paclobutrazol reduced growth of fraser fir; and ethephon reduced growth of grand fir.
Bruce A. Kimball, Dale L. Nolte, and Kelly B. Perry
Hydrolyzed casein (HC) and retail products that contain HC are evaluated as repellents to minimize deer damage to trees and shrubs. Three different experiments demonstrate that HC is an effective deer repellent. Technical-grade HC completely eliminated browse damage to evergreen shrubs (Gaultheria shallon Pursh.) and conifers (Thuja plicata Donn.) during the test periods. Retail sources of HC (concentrated baby formula powders) are not as effective as pure hydrolyzed protein, but do offer browse protection when alternative sources of browse are available. For nursery, orchard, and reforestation applications, HC is a promising deer repellent to minimize losses due to browse. For the private homeowner, a simple repellent formulated with glue and a HC-containing baby formula may offer considerable browse protection when alternative forage is available.
Karen E. Burr and Rudy M. King
Cold hardiness testing is an important tool used at US Forest Service nurseries for evaluating the physiological quality of conifer stock. Three tests were compared. A whole-plant freeze test without root system insulation permitted evaluation of cold injury without complication by drought symptoms if plants were misted. A cutting freeze test underestimated expected field foliar injury due to high humidity used to maintain the cuttings. An electrolyte leakage test failed to detect economically important bud mortality when buds were less hardy than other tissues.
Data from all three testing methods were analyzed with an original software package consisting of standardized input files and a step-by-step series of fortran programs and command files for use with commercially available non-linear modelling programs. Injury (y) versus temperature (x) data were modelled with the versatile, 4-parameter Weibull sigmoid model. Injury estimates at specific temperatures (Ix) or temperature estimates causing specific injury levels (LTy) were calculated with confidence and calibration intervals, respectively. The statistical significance of differences between Ix or LTy estimates was then determined.
Mondher Bouden, Jaaues-Andre Rioux, and Isabelle Duchesne
The agricultural valorization of waste, rich in organic matter and minerals, is one of the best economical and ecological methods of disposal. This study was carried out to evaluate the release of mineral elements restrained in fresh bio-filters, composted sewage sludges, and composted de-inking sludges, and their effects on growth of Physocarpus opulifolius `Nanus' produced in containers. The physical and chemical analysis of the organic residues proved that the fertilization value of composted sewage sludges was greater than the other residues. Moreover, the granular characteristics of fresh biofilters and composted de-inking sludges were finer than composted sewage sludges. Each organic residue was combined, in proportion of 10%, with peatmoss, composted conifer bark, and fine crushed gravel. The regular leaching of container medium showed that the composted sewage sludges release a higher quantity of major mineral elements. Physocarpus opulifolius `Nanus' plants were larger than those plants grown in the control substrate (without residue). The results obtained in media containing fresh bio-filters or composted de-inking sludges were similar to those obtained in the control substrate.
Mondher Bouden, Jacques-Andre Rioux, and Isabelle Duchesne
Three ornamental species (Spiraea japonica `Little Princess', Physocarpus opulifolius `Nanus', and Prunus × cistena) were potted in seven different substrates. The control substrate contained peatmoss, composted conifer bark, and fine crushed gravel (5:4:1, by volume). In the other six substrates, peatmoss was partially or completely substituted by different proportions of three organic residues (10% or 50% of the mixture made up of fresh bio-filters, 5% or 10% in composted sewage sludges, and 10% or 40% in composted deinking sludges). Four fertilization regimes (0, 200, 400, and 600 mg N/liter in the form of soluble fertilizer 20–20–20) were applied weekly onto containers. The experimental design was a split-plot with six replications. Physical and chemical analysis of the organic residues proved that the composted sewage sludges were richer in minerals than the other residues. Moreover, fresh bio-filters and composted deinking sludges were less granular than composted sewage sludges. The 10% proportion of each organic residue, combined with the other materials, was the most-adequate proportion and did not reduce the growth of plants (height, aerial and root dry matter). In addition, a dose of 400 mg·liter–1 generally gave good results, especially for fresh bio-filters and for composted sewage sludges. However, it is preferable to use a higher dose (600 mg·liter–1 if composted deinking sludges are used.
B. Dehgan, F. C. Almira, and T. H. Yeager
Rooted cuttings of Photinia X fraseri and Podocarpus macrophyllus were grown in Metro-mix 500 amended with 0.0, 0.25, 0.50, 0.75, or 1.0% (w/w) Stockosorb 300, a K-based superabsorbent polymer. All 3-liter containers were irrigated with 500 ml of 100, 200, 300, or 400 ppm 20N-8.7P-16.72K Peters fertilizer solution once every 3, 6, 9, or 12 days, respectively. In comparison with the unamended media, P. X fraseri had equal or better growth (shoot and root fresh and dry weights, increased height, and branch and leaf numbers) with 3, 6, and 9 day irrigation in all but the 1 % amended medium. Growth of P. macrophyllus was not noticeably affected by the polymer amendment. This is not unexpected since P. X fraseri is a broad-leaf plant while P. macrophyllus is a slow growing, narrow-leaf conifer. Nitrogen, P, and K tissue levels for Photinia and Podocarpus decreased for the 12 day irrigation treatment regardless of amendment rate. Except for Fe, which was highest at nine day irrigation intervals, micronutrients remained more or less constant in both species. The amended media had a greater water holding capacity at termination of the project (144 and 192 days for Photinia and Podocarpus, respectively) than at the start. Thus, K-based superabsorbents may be used successfully to reduce irrigation frequency.
Farrell C. Wise, Laura L. Greenwood, and D. Bradley Rowe
Clonal propagation of recalcitrant conifers like loblolly pine depends on producing juvenile cuttings on hedges sheared several times annually. Although dormant cuttings root well, it will be economically important to also root softwood shoots produced between shearings. Several variables were therefore evaluated in a factorial experiment to enhance rooting and handling of summer cuttings. Rooting percentages were equivalent for 3 media after a 5-week hardening period (56% overall), but open flats of 1 perlite:1 vermiculite induced larger root systems at the end of rooting and hardening phases. Extending the rooting period from 10 to 14 weeks increased rooting from about 45% to 58% by the end of hardening. Primary root length per cutting increased 12-63% during hardening, depending on medium. After transplanting, overwintering survival was 98%. Foam rooting wedges produced smallest root systems, and resulting plants were consistently shortest through the following growing season. Weekly applications of soluble fertilizer during the last 6 weeks of rooting did not improve rooting or subsequent growth
David Creech, Greg Grant, and Dawn Parish
The SFA Mast Arboretum began as a landscape plant materials class project on the south side of the Agriculture building in 1985. In 2000, over 20 theme gardens now occupy 18 acres. The garden is computer mapped and an accessioning system is in place. Theme garden developments include daylilies, herbs, a rock garden, a xeriscape, plants for shade, wetland, and bog conditions, a line of vines, an Asian Valley, conifers and hollies, and numerous gardens that trial and display herbaceous perennials. Recent developments include a children's garden and, the biggest project to date, an 8-acre SFA Ruby Mize Azalea garden, with a grand opening in Apr. 2000. Theme gardens are utilized to display collections. Significant assemblages include Rhododendron (400 cultivars and selections), Acer (168 cultivars), Camellia (210 cultivars), Loropetalum (18 taxa), Cephalotaxus (43 taxa), Magnolia (47 taxa), Abelia (37 taxa), Ilex (73 taxa), and others. Plant performance and observational information is recorded. Second author Grant has numerous plant introductions in the past 5 years, many that are well represented in the nursery industry and recognized by TAMU's Coordinated Educational and Marketing Assistance Program (CEMAP) as “Texas Superstar” promotions (trademarked). SFA Mast Arboretum plants are promoted via distributions, trade articles, and the Arboretum's website: www.sfasu.edu/ag/arboretum.
Kenneth R. Schroeder and Janet E. Schroeder
According to brain-based learning theory, learning is enhanced by challenge and inhibited by threat. Effective learning occurs when students are immersed in the educational experience, challenged yet not threatened, and encouraged to actively process information. All of these components are part of simulation or role-play games. With these basic concepts in mind, we approached the challenge of enhancing student learning in a plant identification course taught in a large class setting. Considering that plant identification requires some basic detective skills, and the popularity of criminal investigation television programming, we designed a role-play exercise involving case files, investigation zones, and detective teams. As a spin-off from the television shows “CSI: Crime Scene Investigation” and “CSI: Miami,” the exercise was coined “CSI: Manhattan, Conifer Site Investigation in Manhattan, Kansas.” It was designed to fit into a 50-minute class period. Throughout the exercise, detective teams (students) needed to collectively locate and identify plants based on previous knowledge and clues within the case files and at the sites. Upon completion, plant specimens were checked in and identification logs discussed in order to provide immediate feedback and reinforcement of learning. Students enjoyed the exercise, offering positive feedback and conversations about the exercise throughout the balance of the semester. Six months later, while walking past one of the investigation sites, students remembered the site, exercises performed, and the plant name. The exercise includes both interactive and experiential learning components. This session will discuss the “CSI” exercise and its value in linking action to information.