Patmore green ash (Fraxinus pennsylvanica `Patmore'), Bur oak (Quercus macrocarpa), and Austrian pine (Pinus nigra), were used to measure growth differences of trees produced using three different production methods: balled and burlapped, plastic container, and fabric container (grow bag). Two irrigation frequencies were also established. A pressure chamber was used to measure the xylem water potential and to determine tree water requirements and irrigation scheduling. The balled and burlapped trees showed the least new growth of the three production methods across all three tree types. The production method showing the most new growth varied by genera. Plastic container ash trees grew considerably more than the fabric container ash; fabric container oak grew significantly more than plastic container oak; and there was no measurable difference between the new growth of the plastic container and fabric container pines. The fabric container transplants required more frequent irrigation than did the balled and burlapped trees. Under high temperature and drought conditions, fabric container trees showed stress earlier than did the balled and burlapped or plastic container trees.
Roberta J. Tolan and James E. Klett
Scott G. Reeves and James E. Klett
Three commonly used nursery media were packed into 10×40 cm long PVC plastic columns. Two treatments of aqueous applied napropamide [2-(αnapthoxy)-N,N diethyl propionamide] were used including: 1) 13.44 kg/ha, 2) 20.16 kg/ha. Two water treatments were applied to the columns: 1) 2.54 cm/.405 ha, 2) 5.08 cm/.405 ha. Leachate from the columns was collected every three days for a period of two weeks. Quantitative bioassay testing using a napropamide sensitive plant species Hordeum vulgare L. (barley) have indicated a downward linear trend in the growth of roots and shoots when exposed to increasing concentrations of napropamide in controlled petri dish experiments. Preliminary leachate studies indicate that napropamide concentrations in the leachate collected are below levels detectable by the barley bioassay (< .25 ppm) at the label recommended rate of 6.72 kg/ha. Gas chromatography studies will be conducted to confirm napropamide concentrations in the collected leachate.
Scott Dunn, David Staats, and James E. Klett
During the 1996 season, pre-emergent herbicides were applied to container-grown herbaceous perennials and evaluated on the basis of weed control, phytotoxicity, and effect on plant growth. The herbicides and rates were: Napropamide (Devrinol 10G), 0.72 and 1.44 kg a.i./ha; Oryzalin (Surflan 40AS), 0.36 and 0.72 kg a.i./ha; Oxadiazon (Ronstar 2G), 0.72 and 1.44 kg a.i./ha; Oxyfluorfen + Oryzalin (Rout 3G), 0.54 and 2.16 kg/ha; Oxyfluorfen + Pendimethalin (Scott's OH II),0.54 kg a.i./ha; and Trifluralin (Treflan 5G), 0.72 and 1.44 kg a.i./ha. Herbicides were applied to Campanula carpatica, Dianthus gratianopolitanus, Gaillardia × `Baby Cole', Penstemon × `Husker's Red', and Phlox subulata `Emerald Blue'. Phytotoxicity symptoms (visual defects and less height) were apparent with Oryzalin on Penstemon (at both rates) and on Phlox (0.72 kg a.i./ha). Weed control was significantly less with Trifluralin and Napropamide when compared to the other herbicides.
James E. Klett, David Staats, and Matt Rogoyski
During the 2004 season, preemergence herbicide was applied to 12 container-grown herbaceous perennials and woody plants and evaluated for weed control, phytotoxicity, and effect on plant growth. The herbicide and rates were: pendimethalin (Pendulum 2G) 908 g (label rate), 1816 g, and 3632 g/acre a.i. Herbicides were applied to lady's mantle (Alchemilla mollis), purple rock cress (Aubretia species), blue wild indigo (Baptisia australis), pink pussytoes (Antennaria dioica var. rosea), common sneezeweed (Helenium autumnale), redhot poker (Kniphofia uvaria), showy goldenrod (Solidago speciosa), heartleaf foamflower (Tiarella cordifolia), lavender (Lavendula angustifolia), blue flax (Linum perenne), catmint (Nepeta ×faassenii), and hen and chicks (Sempervivum tectorum). At 32 and 117 days after application, plants were evaluated for phytotoxicity. No phytotoxicity symptoms were apparent on any of the plants tested. Weed control was good in most cases with this herbicide but it did not control all weeds. Increasing the rates from 1× (label rate) did not significantly improve weed control.
James E. Klett, David Staats, and David Hillock
During the 1992 season six preemergent herbicides (Devrinol) at 4.5 and 9.1 kg/ha, Metolachlor (Pennant) at 4.5 and 9.1 kg/ha, Isoxaben (Gallery) at 1.1 and 2.3 kg/ha, Oxyfluorfen + Oryzalin (Rout) at 3.4 and 13.6 kg/ha, Oryzalin (Surflan) at 2.8 and 4.5 kg/ha and Trifluralin (Treflan) at 4.5 and 9.1 kg/ha, were tested on Rudbeckia fulgida “Goldstrum”, Digitalis purpurea “Excelsior”, Chrysanthemum maximum “Alaska”, Stokesia laevis “Blue Danube”, and Geum hybrids “Mrs. Bradshaw”. Gallery at both rates resulted in visual phytotoxicity on Chrysanthemum, Digitalis and stunting in Rudbeckia at the 2.3 kg/ha rate. During the 1993 season the same herbicides plus Oxadiazon (Ronstar) at 4.5 and 9.1 kg/ha, were tested on Achillea tomentosa, and Thymus pseudolanuginosus. Gallery and Pennent at both rates resulted in visual phytotoxicity and stunted growth on Thymus pseudolanuginosus. Rout at the 13.6 kg/ha rate resulted in visual phytotoxicity on Achilles tomentosa.
Harrison G. Hughes and James E. Klett
The Dept. of Horticulture and Landscape Architecture offers majors in Horticulture with four concentrations (Floriculture, Horticultural Business Management, Horticultural Food Crops, and Horticultural Science) and Landscape Horticulture with three concentrations (Landscape Design and Construction, Nursery and Landscape Management, and Turf Management). A third major in Landscape Architecture is also offered. The department maintained the concentrations in past years of low enrollment by switching courses to alternate years, dropping nonmajor courses, and through hiring part-time staff. Currently, increasing enrollments, with limited additional funding and the need for broadened general requirements, increased career guidance, and capstone courses have increased pressures on consolidation of concentrations. Faculty have refocused senior courses to create capstone courses in several concentrations, moved the senior seminar to sophomore status for career enhancement, and are currently discussing other options.
James E. Klett, David Hillock, and David Staats
Herbicides were applied to container-grown herbaceous perennials and evaluated on the basis of weed control, phytotoxicity, and effect on plant growth. During the 1995 season six preemergent herbicides [(in kg·ha–1) Napropamide (Devrinol 10G), 4.5 and 9.1; Isoxaben (Gallery 75DF), 1.1 and 2.3; Oxadiazon (Ronstar 2G), 4.5 and 9.1; Oxyfluorfen + Oryzalin (Rout 3G), 3.4 and 13.6; Oryzalin (Surflan AS), 2.8 and 4.5; and Trifluralin (Treflan 5G) 4.5 and 9.1, were tested on Callirhoe involucrata, Delosperma nubigenum, Dendranthemum ×morifolium `Jennifer', Festuca cinerea `Sea Urchin', and Gypsophila paniculata `Fairy's Pink'. Isoxaben (both rates) resulted in visual phytotoxicity symptoms and sometimes death to Dendranthemum. Oxadiazon (9.1 kg·ha–1) and Oxyfluorfen + Oryzalin (both rates) resulted in plant chlorosis and necrosis to Delosperma soon after herbicide application, but plants outgrew herbicide damage. Napropamide (both rates), applied to Delosperma, resulted in less dry weight when compared to some of the other herbicide treatments. Oryzalin (4.5 kg·ha–1) resulted in visual phytotoxicity and less plant dry weight to Festuca. Data analysis revealed no significant differences in Callirhoe and Gypsophila. In general, most herbicides controlled weeds effectively.
Sean J. Markovic and James E. Klett
The objective of these experiments was to evaluate the reaction of ‘Snow Angel’ coral bells (Heuchera sanguinea) and Orange Carpet hummingbird trumpet (Epilobium canum ssp. garrettii ‘PWWG01S’) to repeated foliar applications of three plant growth regulators at two application rates. The plant growth regulators applied during a stock plant study and followed by a propagation study were 200 and 400 ppm ethephon, 250 and 500 ppm benzyladenine, and 50 and 100 ppm gibberellic acid 4 and 7 (GA4+7) + benzyladenine. The stock plant study was conducted to assess the efficacy of plant growth regulators, vegetative growth (height and width growth index), the number of vegetative cuttings, as well as the fresh weight (FW) and dry weight (DW) of the harvested vegetative cuttings. The propagation study was conducted to determine the effects of the plant growth regulator treatments on the rooting of the vegetative cuttings. The stock plant study showed that GA4+7 + benzyladenine (50 and 100 ppm) significantly increased production of ‘Snow Angel’ coral bells cuttings compared with all other treatments. However, no significant differences in FW or DW were observed with ‘Snow Angel’ coral bells between treatments. In the propagation study, no significant difference in rooting percentage was observed after 4 weeks. The Orange Carpet hummingbird trumpet stock plant study resulted in a greater number of vegetative cuttings with GA4+7 + benzyladenine (50 and 100 ppm) and benzyladenine (250 ppm) treatments. Fresh weight of vegetative cuttings harvested from plants treated with GA4+7 + benzyladenine (50 or 100 ppm) were the lowest. The only treatment that showed increased vegetative cutting production with no effect on FW was benzyladenine (250 ppm) on Orange Carpet hummingbird trumpet.
Sean J. Markovic and James E. Klett
This study aimed to assess the effects of plant growth regulators (PGRs) on stock plant production of mojave sage (Salvia pachyphylla) and ‘Avalanche’ cape daisy (Osteospermum hybrid) that received foliar sprays of the following three PGRs: 200 and 400 ppm ethephon; 250 and 500 ppm benzyladenine; and 50 and 100 ppm gibberellic acid 4 and 7 (GA4+7) plus benzyladenine. Vegetative growth [height and width growth index (GI)], the number of vegetative cuttings, and fresh weight (FW) and dry weight (DW) of the harvested vegetative cuttings data were collected. A propagation study was conducted concurrently to determine the effects of the PGR treatments on rooting vegetative cuttings. GA4+7 plus benzyladenine (50 and 100 ppm) increased the production of both mojave sage and ‘Avalanche’ cape daisy cuttings by ≥18% more than the other treatments. The GI, FW, and DW results showed similar trends across experiments 1 and 2 for each perennial. In the propagation study, the rooting percentage did not differ after 4 weeks, indicating that the use of GA4+7 plus benzyladenine in production protocols could benefit producers of both perennials.
Jennifer M. Bousselot, James E. Klett, and Ronda D. Koski
This research examined plant area covered (plant cover) for six plant species on an existing modular extensive green roof in a semiarid climate. Species evaluated were Antennaria parvifolia Nutt., Bouteloua gracilis (Kunth) Lag., Delosperma cooperi (Hook. f.) L. Bol., Eriogonum umbellatum Torr. aureum ‘Psdowns’, Opuntia fragilis Nutt., and Sedum lanceolatum Torr. Many methods for measuring plant cover are subjective and based on semiquantitative measurements. This study compared digital image analysis data (DIA) with manually collected converted two-dimensional data (C2D) for plants grown on an extensive green roof. For each plant in the study, digital images and manual two-dimensional measurements were taken on four dates (at 6-week intervals) in 2008 and on four dates (at 6-week intervals) in 2009. Additionally, comparisons between DIA data and final biomass, and C2D and final biomass, were performed. Plant cover increased for all six species during the 2008 growing season. However, E. umbellatum aureum ‘Psdowns’ had a low overwintering rate (12.5%) and was removed from analysis in 2009. In the spring of 2009, four of the five remaining species exhibited decreased plant cover as a result of winter dieback; the one exception was O. fragilis. In terms of plant cover, both quantification methods (C2D and DIA) revealed that B. gracilis and D. cooperi had more plant cover than A. parvifolia, O. fragilis, and S. lanceolatum by the end of the study. Thus, five of the six species evaluated in this study are appropriate for use in extensive green roof applications in semiarid regions. High levels of correlation were found between the DIA and C2D data sets (r = 0.77) averaged over the five species on all eight data collection dates. The groundcover species (A. parvifolia, D. cooperi, and S. lanceolatum) had a higher correlation on average (r = 0.83) than the upright (B. gracilis, r = 0.70) and decumbent (O. fragilis, r = 0.65) species. Additionally, DIA and final biomass correlations showed parallel trends with groundcovers averaging r = 0.83, upright r = 0.64, and decumbent r = 0.41. Therefore, using DIA to evaluate plant cover and biomass accumulation is especially appropriate for groundcover species.