Ligustrum japonicum, Rhododendron indica `Southern Charm' and Viburnum odoratissimum in 10-L containers were placed in a square grid pattern and overhead irrigated using impact sprinklers (30.3 L/min). Plants were irrigated with 12.5 mm with containers touching and, at 5 cm spacings, up to 50 cm between containers. Irrigation water reaching container surfaces (percent capture) increased for all species as container spacing increased. However, the increase in percent capture did not increase irrigation application efficiency because the percent of production area covered by the containers declined as spacing increased. Application efficiency declined with each increase in spacing to a low of 7%. The effects of intraand inter-canopy interference are discussed.
Richard C. Beeson and Thomas H. Yeager
Michael P. Crotser, Leslie A. Weston, and Robert McNiel
Sulfentrazone is a promising new herbicide now under evaluation for use in agronomic and ornamental cropping systems. Sulfentrazone selectively controls yellow nutsedge, morningglories, and other annual grasses and broadleaf weeds. Research was conducted to evaluate the efficacy of sulfentrazone in combination with other labeled products for preemergence weed control in nursery crops. Treatments included sulfentrazone at 0.56 and 1.12 kg a.i./ha and sulfentrazone at 0.37 kg a.i./ha in combination with the following; dithiopyr at 0.37 kg, oxyfluorfen at 0.56 kg, metolachlor at 3.36 kg, isoxaben at 0.56 kg, norfluorazon at 2.64 kg, and isoxaben plus oryzalin at 2.24 kg a.i./ha. Combinations of sulfentrazone with isoxaben or metolachlor provided superior control of morningglory spp., honeyvine milkweed, Carolina horsenettle, and yellow nutsedge. Sulfentrazone plus oxyfluorfen or isoxaben plus oryzalin also provided good control. Poorest overall control was obtained with sulfentrazone plus dithiopyr. Viburnum and deciduous holly were slightly injured 4 WAT with sulfentrazone plus metolachlor. Sulfentrazone plus dithiopyr treatments resulted in serious injury to burning bush 4 WAT and slight injury at 8 WAT.
David L. Creech
The SFA Arboretum is evidence that small horticulture programs can capitalize on what's right outside the back door of the building. Initiated in 1985 as a lab project in a landscape plant materials course on the south side of the Agriculture building, the collection has grown to over 3000 taxa displayed in a ten-acre public garden setting. The Arboretum's mission is to 1) promote the conservation and use of native plants, 2) evaluate “new” landscape plant materials, and 3) serve as a living laboratory for students in Horticulture, Agriculture, Biology and Forestry. Funding improvements in the last two years and the creation of a Board of Advisors and a Volunteer Corps organization has addressed problems in routine landscape maintenance and getting “new” garden developments off the ground. A “Plants with Promise” program acquires, tests, propagates, distributes and promotes superior “new” woody plants. Outstanding performers include Bignonia capreolata 'atrosangainea', Campsis grandiflora, Cinnamomum chekingensis, Euschapis japonica, Scuttelaria suffretescens 'pink', Sinojackia rehderiana, Taxodium mucronatum, Viburnum propinquum, various Styrax species and varieties, several Michelia species, Illicium henryi, three Mexico oaks, and many others. AutoCAD maps and a plant inventory database tracks plant location and acquisition data. A just-completed GIS-based analysis of the university forest paves the way for a campus-as-arboretum effort. The premise of this paper is that high-visibility, easy-access display/evaluation gardens offer Horticulture Departments the opportunity for enhanced student recruitment, community involvement, external funding, environmental education, and the potential for significant contributions to the nursery industry.
Jyotsna Sharma and Jim Rich
Plants infected with Meloidogyne spp. (root-knot nematodes) often are stunted and lose aesthetic value due to chlorosis, wilting, and leaf margin necrosis. We assessed reproduction of three root-knot nematode species, Meloidogyne arenaria, M. incognita, and M. javanica, on five plant taxa native to the southeastern U.S. The plant taxa included were: Hydrangea quercifolia `Oakleaf', Viburnum obovatum `Densa', Itea virginica `Little Henry', Illicium parviflorum, and Clethra alnifolia `Ruby Spice'. Three commonly grown non-native shrubs, Ligustrum japonicum `Texanum', Ilexcrenata `Compacta', and Buxus microphylla `Wintergem', also were included in the study to serve as susceptible, positive controls. Highest gall rating (10) was observed on roots of I. crenata `Compacta' infected with M. incognita, but highest number of eggs (6397 eggs/g of roots) was observed in plants of this cultivar inoculated with M. javanica. Few or no galls were observed on roots of the five native plant taxa, and nematode eggs were recovered only from roots of I. virginica `Little Henry' inoculated with M. arenaria and M. javanica (13 and 20 eggs/g of roots, respectively). Fresh weights of shoots or roots were not affected by nematode inoculation. Due to lack of root gall development and little or no reproduction on the native taxa, we conclude that these are resistant or immune to the three species of Meloidogyne and might be suitable for planting in infested soil.
Robert F. Gorman and Julie Roller
Ten plant species native to southeast Alaska and surrounding regions were selected based on their value as ornamentals, food crops, disturbed site revegetation, and traditional Native American uses. Between 2003–05, seeds, cuttings, rhizomes, and bulbs from the 10 native plant species were collected in Sitka, Alaska, and propagated according to existing plant propagation protocol for each species. The most successful propagation method for each species was determined from field trials. This information was provided through workshops and Extension publications to gardeners in southeast Alaska and other parts of Alaska. The purpose of this project was to enhance growing local native plants as ornamentals, food crops, in disturbed site revegetation and for traditional Native American uses, particularly among native elders unable to collect these plants in the wild. A secondary purpose was to create a market for native plants in southeast Alaska and spawn a cadre of local cottage market gardeners to grow native plants for existing small nurseries. The 10 species selected included: Cornus canadensis, C. stolonifera, Empetrum nigrum, Fritillaria camschatcensis, Linnaea borealis, Oplopanax horridus, Rubus chamaemorus, Vaccinium parvifolium, Vaccinium ovalifolium, and Viburnum edule.
Robert H. Stamps and Daniel W. McColley
Five preemergence herbicides (prodiamine 0.5 G, prodiamine 65 WDG, dithiopyr 0.27 G, thiazopyr 2.5 G, and oxyfluorfen + pendimethalin 3 G) were evaluated for weed control and crop safety on 18 plants (Acer rubrum, Agapanthus africanus, Asparagus densiflorus, Camellia sasanqua, × Cupressocyparis leylandii, Cycas revoluta, Galphimia gracillis, Gelsemium sempervirens, Illicium parviflorum, Lantana camara, Loropetalum chinense, Myrtis communis, Ophiopogon jaburan, Plumbago, Quercus virginiana, Rhododendron, Viburnum suspensum, and Zamia floridana. Herbicides were applied at 1.7 kg a.i./ha, except for oxyfluorfern + pendimethalin, which was applied at 3.4 kg a.i./ha. Treatments were applied twice at 4-month intervals. Untreated and weed-free controls were used to determine herbicide effects on weeds and crops, respectively. All herbicide treatments reduced weed growth (dry-weight basis) and weeding times. Major weeds were dogfennel [Eupatorium capillifolium (Lam.) Small], southern crabgrass [Digitaria ciliaris (Retz.) Koeler], yellow woodsorrel (Oxalis stricta L.), tasselflower (Emilia spp.), and hairy crabweed [Fatoua villosa (Thumb.) Nakai]. Based on weed dry weights, overall weed control for the first 4 months was higher for diazopyr, thiazopyr, and prodiamine G than for the combination treatment. At 8 months, weed growth was similar for all herbicide treatments. The combination treatment was acutely phytotoxicity to more crops than the other treatments; however, phytotoxicity varied with crop, active ingredient, and formulation.
Breeding, selection and evaluation of woody landscape plants has been an active project at the Univ. of Minnesota for many years. The goal of the project is to develop and or identify superior plants that are well adapted to the climatic conditions of Minnesota and other northern areas. About 20 cultivars of many species have been introduced to the nursery trade through this program in the past 20 years. These introductions result from selections made from populations arising from controlled crosses and from open-pollinated populations and native plant populations. One of the primary efforts has been development of the cold hardy, “lights series” of deciduous azaleas. These possess flower bud hardiness of from –35 to –40 °C. Other current breeding activities include efforts with Viburnum, Acer rubrum, Rosa, and intergeneric hybridization in the Pomoidaea subfamily of Rosaceae. An integral part of the project is development and use of techniques to screen for tolerances to various environmental stresses. Approaches used will be discussed and plants currently under evaluation will be described and illustrated with slides.
Katie L. Dylewski, Amy N. Wright, Kenneth M. Tilt, and Charlene LeBleu
The effect of short interval cyclic flooding on root and shoot growth of ‘Shamrock’ inkberry holly (Ilex glabra), ‘Henry's Garnet’ sweetspire (Itea virginica), and ‘Winterthur’ possumhaw (Viburnum nudum) was studied in a greenhouse in Auburn, AL. Liners (4.4 inches long) of each species were planted into trade 1-gal pots in 1 pine bark:1 peat by volume (PB:P) or fine textured calcined clay (CC). ‘Shamrock’ inkberry holly and ‘Henry's Garnet’ sweetspire were planted 18 Apr. 2008; the experiment was repeated with the addition of ‘Winterthur’ possumhaw on 16 June 2008. Plants were flooded to substrate level for 0 (non-flooded), 3, or 7 days. Flooding cycles were repeated at least five times with 7 days of draining between each flood cycle. During draining, plants received no irrigation. Non-flooded plants were watered as needed. Flooded plants for all species except ‘Winterthur’ possumhaw showed decreased root dry weight, shoot dry weight, and final growth index when compared with non-flooded plants. Survival was higher in CC than PB:P for both experiments. All plants maintained good visual quality and shoot growth. As a result, overall, these plants seemed tolerant of flooding despite differences in growth.
R.C. Beeson Jr.
Three species of woody ornamentals, Viburnum odoratissimum Ker Gawl, Ligustrum japonicum Thunb., and Rhaphiolepis indica Lindl. were transplanted from 3.8-L into 11.4-L containers and grown for 6 months while irrigated with overhead sprinkler irrigation. Irrigation regimes imposed consisted of an 18-mm-daily control and irrigation to saturation based on 20%, 40%, 60%, and 80% deficits in plant available water [management allowed deficits (MAD)]. Based on different evaluation methods, recommendations of 20%, 20%, and 40% MAD are supported for V. odoratissimum, L. japonica, and R. indica, respectively, for commercial production. Comparisons of plant growth rates, supplied water, and conversion of transpiration to shoot biomass are discussed among irrigation regimes within each species. Comparisons of cumulative actual evapotranspiration (ETA) to either shoot dry mass or canopy volume were linear and highly correlated. Results indicated there were minimum cumulative ETA volumes required for plants to obtain a specific size. This suggests that irrigation regimes that restrict daily ETA will prolong production times and may increase supplemental irrigation requirements. Thus the hypothesis that restrictive irrigation regimes will reduce irrigation requirements to produce container plants is false due to the strong relationship between cumulative ETA and plant size.
Jeff B. Million*, Thomas H. Yeager, and Joseph P. Albano
The influence of production practices on runoff from container nurseries was investigated in Spring 2003 (March to July) and Fall 2003 (August to January). Viburnum odoratissimum (Ker-Gawl.) liners were planted in 3.8-L containers with a 2 pine bark: 1 sand: 1 Canadian peat substrate and placed on 1.5 m2-platforms at one of two plant spacing densities: 16 or 32 plants/m2 [spaced to 16 plants/m2 after 13 weeks (spring) or 14 weeks (fall)]. Overhead sprinkler irrigation was applied daily (1 cm) and runoff collected weekly. Osmocote 18 N-2.6 P-10 K was surface-applied to each container (15 g) in the spring and surface-applied or incorporated in the fall. Cumulative runoff averaged 1240 L·m-1; in spring (19 weeks) and 1050 L·m-1; in fall (20 weeks), which represented 72% and 66% of applied irrigation plus rainfall, respectively. The lower density spacing resulted in a 19% increase in cumulative runoff in spring (1340 vs. 1130 L·m-1) but had no effect in fall (970 vs. 890 L·m-1). Weighted average ECwa of runoff decreased 10% (0.436 vs. 0.485 dS·m-1) and 12% (0.420 vs. 0.476 dS·m-1) with the lower density spacing in spring and fall, respectively. ECwa in fall was not affected by fertilizer method. Plant size index [(height + width)/2] was reduced 22% in both spring (38.7 vs. 49.7 cm) and fall (26.9 vs. 34.4 cm) when plants were grown at the lower density spacing throughout production. This reduction in plant size was attributed to container heat stress. Plant size was unaffected by fertilizer application method (fall) but fertilizer incorporation resulted in greener plants than surface-applied fertilizer (60 vs. 53 SPAD readings).