Ilex Crenata Research Articles

Seasonal food habits of a sika deer population in the warm temperate forest of the westernmost part of Honshu, Japan

The rumen contents of 63 sika deer (Cervus nippon Temminck) shot in the westernmost part of Honshu were analyzed by the point‐frame method. The rumen contents were dominated by forbs and the majority of these were evergreen monocotyledonous plants, probably Ophiopogon spp. Evergreen browse leaves (woody leaves), such as Eurya japonica Thunb., Ilex crenata Thunb. and Trachelospermum asiaticum Nakai, were also important, constituting 20–40% of the rumen contents. Other categories accounted for only small proportions, although in summer, graminoids increased but twigs and bark decreased in importance and in fall and winter, fruits and seeds increased in importance. The diet of the deer was characterized by high‐quality foods even in winter and by a stability or less‐pronounced seasonality throughout the year than found in the northern deer. These results were compared with those from other populations, including a northern sika deer population in Japan.

227 Rate of Root Growth of Three Woody Ornamental Species

Root growth is a critical factor in landscape establishment of container-grown woody ornamental species. Kalmia latifolia (mountain laurel) often does not survive transplanting from containers into the landscape. The objective of this experiment was to compare rate of root growth of mountain laurel to that of Ilex crenata `Compacta' (`Compacta' holly) and Oxydendrum arboreum (sourwood). Six-month-old tissue-cultured liners (substrate intact) of mountain laurel, 1-year-old rooted cutting liners (substrate intact) of `Compacta' holly (liner holly), 6-inch bare root seedling liners of sourwood, and 3-month-old bare-root rooted cuttings of `Compacta' holly were potted in containers in Turface™. Prior to potting, roots of all plants were dyed with a solution of 0.5% (w/v) methylene blue. Plants were greenhouse-grown. Destructive harvests were conducted every 2 to 3 weeks (six total harvests). Length, area, and dry weight of roots produced since the start of the experiment, leaf area, and dry weight of shoots were measured. Sourwood and liner holly had greater rate of increase in root length and root dry weight than mountain laurel and bare root holly. Rate of increase in root area was greatest for sourwood, followed by (in decreasing order) liner holly, mountain laurel, and bare-root holly. Increase in root length and root area per increase in leaf area was highest for liner holly, possibly indicating why this species routinely establishes successfully in the landscape. Increase in root dry weight per increase in shoot dry weight was lowest for mountain laurel. The slow rate of root growth of mountain laurel (compared to sourwood and liner holly) may suggest why this species often does not survive transplanting.

First Report of Armillaria mellea on a Fern from Italy.

Several perennial species of rhizomatous herbaceous ferns are cultivated as ornamental foliage plants. During late summer 1999, in a garden at the foot of Mount Etna, eastern Sicily (Italy), we noted a fern hedge showing patches of withered or stunted plants. The fern was identified as Cyrtomium falcatum (L.f.) C. Presl. (=Polystichum falcatum (L.f.) Diels), a house holly fern or Japanese holly fern, which is an ornamental fern native to East and South Asia. Other woody plants in the immediate vicinity had died over the last few years, including apricot and cedar trees whose stumps had not been removed. A close examination of uprooted ferns revealed the presence of creamy white fan-shaped mycelial mats with an odor typical of Armillaria species that were intermixed with the felt-like tangle formed by the rhizomes and roots of the ferns. In autumn, clumps of honey mushrooms with an annulus grew around patches of the withered fern hedge and in other parts of the same garden. The spore print of the basidiocarp was light cream. Basidiospores (8 to 9 × 5 to 6.5 µm) examined under a microscope were hyaline and apiculate. The fungus was isolated in pure culture from infected rhizomes with the selective medium of Kulman and Hendrix (3). In pure culture on 2% malt agar, the fungus formed ribbon-shaped, contorted, fast-growing rhizomorphs that branched profusely. Mycelial proteins of the isolate were analyzed by both polyacrylamide slab gel and starch gel electrophoreses, as described by Bragaloni et al. (1). The electrophoretic patterns of five isozymes (esterase, glutamic oxalacetic transaminase, phospho-glucomutase, alcohol dehydrogenase, and polygalacturonase) of the isolate from fern were identical to those of the reference isolate of A. mellea (Vahl:Fr.) Kumm. from grapevine. Conversely, the patterns were clearly distinct from those of reference isolates from other species, including A. ostoyae (Romagnesi) Herink, A. bulbosa (Barla) Kile et Watling, and A. cepistipes Velenovsky. Thus, on the basis of cultural, morphological, and biochemical characteristics, the species infecting the fern was identified as A. mellea. This pathogen, very common and widespread on wooded or previously wooded sites, has an extremely wide host range, encompassing both woody and herbaceous plants (2,4). However, this is the first report of A. mellea on a fern in Italy.

Yellow Nutsedge Control and Nursery Crop Tolerance with Manage as Affected by Adjuvant Choice

Abstract Adjuvants combined with one-half rate (18 g ai/ha, 0.26 oz ai/A) of Manage (MON 12051, halosulfuron) were evaluated for phytotoxicity on five species of landscape plants grown in containers and for effectiveness of yellow nutsedge (Cyperus esculentus L.) control. Adjuvants tested at 0.25 and 0.5% (v/v) were: X-77 (non-ionic), Scoil (methylated soybean seed oil), Sun-It II (methylated sunflower seed oil), Agri-Dex (paraffin crop oil concentrate), and Action “99” (non-ionic organosilicone). Manage combined with each adjuvant injured Japanese holly (I. crenata Thunb. ‘Bennett's Compacta’), forsythia (Forsythia x intermedia Zab. ‘Lynwood Gold’), green liriope (Liriope muscari Bailey ‘Big Blue’), and weigela (Weigela florida Bunge ‘Pink Lady’), but not ‘Blue Girl’ holly (Ilex x meserveae S.Y. Hu ‘Blue Girl’). Manage with Scoil produced moderate phytotoxicity on forsythia and weigela and reduced growth of all landscape plants. Manage plus Action “99” caused severe phytotoxicity to weigela and reduced growth on all plants tested. Manage plus Agri-Dex treatment resulted in moderate to severe growth reduction to all plants, with severe marginal necrosis of foliage on forsythia and weigela. Manage with Sun-It II resulted in less growth reduction and fewer phytotoxic symptoms of the test species, compared to other adjuvant plus Manage combinations. Initially, foliar chlorosis was observed on all species except ‘Blue Girl’ holly with the Manage plus Sun-It II treatment, but most plants had recovered by 8 weeks after treatment (WAT). Yellow nutsedge control at 4WAT was greater when Manage (18 g ai/ha, 0.26 oz/A) was combined with Scoil, Sun-It II, Agri-Dex, or Action “99” adjuvants. By 8WAT, Manage combined with Sun-It II resulted in 98–100% control of nutsedge. Manage plus the adjuvants Scoil or Sun-It II resulted in superior yellow nutsedge control compared to X-77, Action “99”, or Agri-Dex and had little effect on growth of these landscape plants.

017 Influence of Surfactants on Manage Herbicide Control of Nutsedge and Nursery Crop Tolerance

Research was conducted to compare non-ionic, paraffin-based crop oil, soybean oil, sunflower oil, and organosilicone surfactants combined with Manage (MON 12051, holosulfuron) applied at a reduced rate for yellow nutsedge (Cyperus esculentus) control efficiency and evaluation of phytotoxicity to five container-grown ornamental species. Manage at 0.018 kg a.i./ha was combined with 0.25% or 0.5% (v/v) of the following surfactants: X-77, Scoil, Action “99”, Sun It II, or Agri-Dex. Yellow nutsedge tubers (10 per 3.8-L container) were planted into containers along with the following nursery crops: `Lynnwood Gold' forsythia, `Big Blue' liriope, `Pink Lady' weigela, `Blue Girl' Chinese holly, and `Bennett's Compacta' Japanese holly. Treatments were applied 5 weeks after potting on 13 June 1998 and phytotoxicity ratings taken 4 and 8 weeks later and growth measured after 8 weeks. Sun It II provided the most-effective nutsedge control without reducing growth and causing minimal phytotoxicity to the ornamental plants tested. X-77 (the recommended surfactant for Manage) provided only moderate nutsedge control. Efficient nutsedge control can be accomplished with Manage at one-half the recommended rate when combined with the correct surfactant. Some temporary phytotoxicity symptoms can be expected and a slight overall growth reduction is possible, depending on the surfactant selected.

610 Evaluation of Sawmill Residue as a Component of Nursery Potting Mix

The standard mix used by most nurseries consist of a 9 pine bark: 1 sand. With the ever-increasing cost of bark, nurseries are looking for an alternative. Sawmill residue may hold potential utility as part of a potting mix. Although sawmill residue is highly variable, it can serve as soil bulk as well as an organic medium. The purpose of this study was to determine if old sawmill residue not treated by pathogen-free requirement procedures could be used “as is” as part of a nursery soil mix. For this study, a sample, a typical conglomerate of undetermined wood chips, bark, and soil particles, was obtained from an “old pile” (just how old is not known) of sawmill residue. To determine how this sample would function in a nursery bark/sand mix, tests were run on its physical properties of pore space and water-holding capacity. The sawmill residue had the following characteristics: a mean 44.2% porosity capacity, 23.4% air space, and 20.8% water holding capacity. A standard fertilizer and lime amendment package was added to the sawmill residue in the same rates as a regular nursery mix. The sawmill residue and the standard nursery mix were then blended according to the treatment percentages. The treatments were sawmill residue/standard nursery mix 0/100, 10/90, 30/70, 60/40, and 100/0. The Ilex crenata `Compacta' liners were planted into standard 1-gallon nursery pots filling to just below the rim. The pots were randomly placed on a well-drained rock surface in full sun. No additional fertilizer was used and watering was done as needed. Plants were grown for 1 year. Visual assessments were made throughout the growing period and at harvest. There was no visible difference in any of the treatments as far as overall growth was discerned. The plants were of uniform height and width showing consistent, even growth and good leaf color. Root system growth and development were evaluated visually and over all treatments were uniformly good. No root problems were noted. There was not any plant loss in any treatment over the entire study. Each plant was cut at the soil line and dried for 24 hours at 1150 °C. Dry weights were taken after the plant material had cooled for 4 hours. Results were based on four plants per treatment times four replications for a total of 16 plants per treatment. There was not any measurable growth difference in dry weight among treatments 1, 2, 3, and 4 [sawmill residue/standard nursery mix 0/100 (41.03 g dry weight), 10/90 (39.83 g dry weight), 30/70 (38.98 g dry weight), 60/40 (37.42 g dry weight)]. However, treatment 5 [100/0 (31.03 g dry weight)] was significantly lower when compared to the remaining four treatments. The lower dry weight may be attributed to the 100% sawmill residue being too heavy and not well-drained enough. However, the roots did not show any damage from being too wet. Further work is being done with the sawmill residue.

121 Fertilizer Formulation, Placement, and Tex-R Geodiscs Influence the Growth of `Compacta' Holly

A study was conducted to compare four different controlled-release fertilizers when used in conjunction with Tex-R Geodiscs on the growth of Ilex crenata Thunb. ex J.A. Murray `Compacta' in 3.8 L (#1) containers. The fertilizers used were Osmocote Plus Southern Formula (18N-3.9P-10K), Osmocote Plus Northern Formula (18N-3.9P-10K), Wilbro (15N-1.7P-7.5K), and Nutricote T-360 (17N-2.6P-6.6K) all applied at the rate of 1.8 kg N/m3. Geodisc treatments were: 1) no disc, 2) fertilizer placed on top of the disc, and 3) fertilizer placed beneath the disc. At 2 and 4 months after the initiation of the study, the growth indices for plants grown with both Osmocote Plus fertilizers were larger than for either of the other two fertilizers. After 7 months, final growth indices were greater for the Osmocote Plus and Wilbro treatments compared to Nutricote. Final leaf, stem, and root dry masses were all greater for the Osmocote Plus fertilizers compared to the other two, as was final plant quality. Plants with fertilizer placed on top of the disc were smaller compared to the no disc or beneath the disc treatments. Geodisc treatment had no influence on shoot dry mass or final plant quality. Data for leachate nutrient analysis and evapotranspiration will also be presented.

Consumer Perceptions of Plant Quality

Plant quality has been identified as one of the most important factors in determining where retail customers shop and which plants they buy. A better understanding of what customers actually mean by “plant quality” can enhance the industry's ability to give customers what they want, and improve the competitive position of individual nursery/garden center businesses. Five common woody ornamentals—flowering dogwood (Cornus florida), red maple (Acer rubrum), azalea (Rhododendron spp.), nandina (Nandina domestica) and `Compacta' holly (Ilex crenata `Compacta')—were selected for a three-part study of consumer perceptions of plant quality. The first component of the study was comprised of three focus groups, conducted during Summer 1995 in New Bern, N.C., and Fall 1996 in Raleigh, N.C. The purpose of the focus groups was to learn more about the specific quality attributes customers use in evaluating trees and shrubs in the garden center. The second component consisted of five different intercept surveys conducted in 1997 and 1998 in Virginia, North Carolina, South Carolina, Florida, Georgia, Alabama, and Tennessee. Purchase intent, rank order, paired comparison, dollar metric and constant sum scales, accompanied by photographs of plant material, were used to interview retail customers in independently-owned garden centers. These studies focused primarily on azaleas and dogwoods. The third component was a hedonic study focusing on azaleas and `Compacta' holly, conducted in the Raleigh, N.C., area in Apr. 1998. Using standard regression analysis techniques, hedonics examines prices and levels of selected attributes to provide an estimate of the marginal implicit price a consumer is willing to pay for an additional unit of a particular attribute.

Diurnal hystereses of stomatal and bulk surface conductances in relation to vapor pressure deficit in a cool-temperate wetland

In order to evaluate the stomatal control on the canopy evapotranspiration, diurnal variations in stomatal conductance ( g s) of individual plants and bulk surface conductance ( G s) of the canopy were measured independently in the Sarobetsu mire of northern Japan. During July–August 1993 and 1994, g s was measured for four species ( Sasa palmata, Moliniopsis japonica, Myrica gale L. var. tomentosa and Ilex crenata var. paludosa) growing in the mire. In July and August 1995, G s was determined using Penman–Monteith equation. In this equation, evapotranspiration rate was determined by the Bowen ratio/energy balance method. Diurnal hysteresis curves of g s in relation to leaf-to-air vapor pressure deficit ( ν) followed different courses from day to day according to the magnitude of ν, and daily maximum g s was correlated negatively with daily maximum ν except for Ilex crenata var. paludosa. Similar clockwise hysteresis curves were observed between G s and vapor pressure deficit at the mean evaporative surface ( D 0), and daily maximum G s decreased with daily maximum D 0 in mid-summer. In particular, on days when daily maximum D 0 increased up to 1.9 kPa, the large decrease in G s decreased the evapotranspiration rate, despite high irradiance levels. Thus, stomatal control by individual plant leaves strongly affects evapotranspiration from the canopy and prevents excessive water loss on days when vapor pressure deficit is high, even when soil water is plentiful. On the rising limb of the diurnal course of the transpiration rate ( T r), increases in T r with change in ν, Δ T r/Δ ν varied from day to day, in particular for M. gale L. var. tomentosa. Further, a negative relationship was found between Δ T r/Δ ν and the rate of increase of ν for unit change in time. We believe that the change of the daily course of g s and T r was caused by the response of stomata to the increased rate of change of ν. Thus, in order to predict the diurnal variation of g s, the magnitude and tendency of ν for each day must be considered.

Biocontrol of Phytophthora capsici by Serratia marcescens F-1-1 and Analysis of Biocontrol Mechanisms Using Transposon-insertion Mutants.

An antagonistic bacterium against Phytophthora capsici, the pathogen of damping-off of cucumber, was isolated from the rhizosphere of scarlet sage (Salvia splendens F. Sellow ex Roem. et Schult.) in Fukui Prefecture. The red-pigmented strain F-1-1 was identified as Serratia marcescens based on its bacteriological properties. The strain F-1-1 strongly inhibited the germination of cystospores and zoosporangia of P. capsici P-9-2 in in vitro tests, and also it suppressed the damping-off of cucumber seedlings inoculated with a cystospore suspension of P. capsici P-9-2 in pot tests. Moreover, all the other red-pigmented S. marcescens strains isolated from the rhizosphere of Japanese holly (Ilex crenata Thunb.) were antagonistic, unlike six non-pigmented Serratia spp. strains. Four mutants defective red pigment biosynthesis were obtained by transposon (Tn7) mutagenesis among 5967 transconjugant clones. These mutants simultaneously lost their antagonistic ability in in vitro and in pot tests. Thus, S. marcescens F-1-1 was found to be a potential biocontrol agent for damping-off of cucumber seedlings and its antagonistic ability was based on the production of antibiotic red pigments.

Growth of Containerized Landscape Plants Is Influenced by Herbicides Residues in Irrigation Water

Herbicides play an important role in the production of nursery crops by reducing weed problems and improving production efficiency. Herbicides applied to nursery crops may move in runoff water into retention basins, which are used to irrigate container plants. Studies investigated the growth and development of containerized landscape plants subjected to irrigation water containing herbicide residues. Containerized dwarf gardenia, Snow azalea, Buccaneer azalea, Hellers Japanese holly, fountain grass, and daylily were grown in fine pine bark medium in the greenhouse and were irrigated with water containing 1 mg/L and 10 mg/L of oryzalin, oxyfluorfen, and isoxaben. Fountain grass and daylily were the most sensitive to herbicide application with reduced root and shoot growth. Oryzalin was the most phytotoxic to fountain grass followed by oxyfluorfen and isoxaben. Oryzalin and oxyfluorfen at 10 mg/L reduced the growth index of fountain grass. Oryzalin was the most phytotoxic herbicide to daylily, followed by isoxaben and oxyfluorfen. Only the high rate (10 mg/L) of oryzalin reduced the growth index of daylily. Among woody species, the root weights of Hellers holly were reduced by 10 mg/L of isoxaben. The growth of other woody species was not affected by the herbicides.

Dolomitic Limestone Form and Rate in Container Production of Woody Ornamentals

Uniform liners of Soft Touch Holly (Ilex crenata 'Soft Touch') and Fashion azalea {Rhododendron 'Fashion') were potted into trade gallon containers of a 3: 1 by volume pinebark: peat moss medium amended with 8.3 kg of 17-7-12 Osmocote and 0.9 kg of Micromax per m3. Dolomitic limestone rates were 0,3, and 6 kg per m3 of medium applied as a finely ground or pelletized product. Medium solution pH increased with increasing rate of dolomitic limestone. Ground dolomitic limestone had a greater impact on medium solution pH than pelletized dolomitic limestone and differences increased as rate increased. Addition of ground dolomitic limestone at 6 kg per m3 reduced foliar color and growth of azalea. Amending with dolomitic limestone had little or no effect on holly foliar color or growth, regardless of rate.

Ozone Sensitivity of Selected Southeastern Landscape Plants

Abstract Twenty-six species and/or cultivars commonly used in landscapes of the southeastern United States were exposed to three ozone (O3) levels for 3-week periods during spring and summer 1994. Thirteen species or cultivars exhibited visible foliar injury at the highest rate, 2.5× ambient, and two cultivars exhibited foliar injury with ambient O3 concentrations. The most sensitive were two cultivars of buddleia or butterfly bush (Buddleia davidii Franch. ‘Black Knight’ and ‘Royal Red’), with visible injury under ambient and 2.5× ambient O3 levels, and ‘White Star’ zinnia (Zinnia angustifolia HBK ‘White Star’) with visible injury observed under 2.5× ambient O3 levels. Seven other cultivars of buddleia and three cultivars of red maple (Acer rubrum L. ‘Autumn Flame’, ‘October Glory’, and ‘Franksred’ (Red SunsetTM)) exhibited minor foliar injury under 2.5× ambient O3 levels. Visible injury was not present on flowering dogwood (Cornus florida L. ‘Stokes Pink’), hollies (Ilex crenata Thunb. ‘Green Luster’, I. cornuta Lindl. & Paxt. ‘Carissa’, I. x attenuate Ashe ‘Fosteri #2’), cultivars of crapemyrtle (Lagerstroemia indica L. ‘Byers Wonderful White’ and ‘Carolina Beauty’), glossy abelia (Abelia x grandiflora (Andre) Rehd.), southern waxmyrtle (Myrica cerifera L.), sawtooth oak (Quercus acutissima Carruth), begonia (Begonia semperflorens-cultorum Hort. ‘Pizzazz Red’), petunia (Petunia x hybrida Hort. Vilm.-Andr. ‘Celebrity Red’), salvia (Salvia splendens Sello. ‘Hotline’), or gomphrena (Gomphrena globosa L. ‘Strawberry Fields’).

Differences in ecological and genetic traits between Panonychus citri (Acari: Tetranychidae) populations infesting citrus and Osmant hus

Comparative studies of the ecological and genetic traits of Panonychus citri (McGregor) populations on citrus and other host plants were conducted. Panonychus citri on Osmanthus trees has a unique esterase allele and host range in comparison with populations on other host plants, for example Citrus unshiu and Ilex crenata. Reproductive incompatibility between P. citri populations on C. unshiu and Osmanthus fragrans was found. Therefore, in Japan, P. citri differentiates into two groups one of which associates with Osmanthus, and the other with other host plants.

Response of ‘Helleri’ holly to nitrogen form and aluminum in solution culture

Rooted cuttings of ‘Helleri’ holly (Ilex crenata Thunb. ‘Helleri') were grown in solution culture for 101 days. On day 31, plants were exposed to 0 and 54 mg‐l‐1 aluminum (Al) and five nitrogen (N)‐form treatments of varying ammonium:nitrate (NH4 +:NO3 ‐) ratios (0:100, 25:75, 50:50, 75:25, and 100:0, percent basis) at pH ≤4.O. Root growth decreased with increasing NH4 + concentration in solution. Uptake of phosphorus (P) was increased by Al. Manganese (Mn) and iron (Fe) uptake were reduced by Al. No significant N‐form effects were determined for nutrient uptake data. Calcium (Ca), magnesium (Mg), potassium (K), Fe, Mn, copper (Cu), zinc (Zn), and boron (B) tissue concentrations decreased in solutions containing 54 mg‐L‐1 Al; while tissue P concentrations increased. Nitrogen source exerted less influence on growth and nutrition of ‘Helleri’ holly than Al.

Population dynamics of the citrus red mite, Panonychus citri (McGregor) (Acari: Tetranychidae) in Japanese pear orchards

In spring a population of the citrus red mite (Panonychus citri),a non-diapausing species, migrated to a Japanese pear orchard, mainly from nearby Japanese holly trees, but in autumn most of the mites starved to death while the rest returned to the holly trees. In the Japanese holly trees, the population of mites reached their maximum density in late May1993 and in mid-June 1994 on overwintered leaves and moved to newly opened leaves in mid-June 1993 and late June 1994. The mites tended to disperse abruptly in early June or mid-June and again towards the end of June. The mites inhabiting the holly trees appeared to migrate to the Japanese pear trees in June but their densities on pear leaves remained low until mid-August. In the pear orchard, the mites initially tended to increase on pear leaves near the holly trees and then gradually spread to other leaves farther away from the holly trees. Their highest density in the pear orchard occurred in mid-October. When pear leaves were inoculated with two or five female adults at different times from May to September, the leaves inoculated before mid-August showed no increase in the number of mites. A possible cause for the suppression of the population increase on pear leaves from June to mid-August is discussed.

Preemergence Herbicide Effects on Nursery Crop Root and Shoot Growth

Abstract The effects of preemergence herbicides on root and shoot growth of redtip photinia (Photinia × fraseri Lindl.), abelia (Abelia× grandiflora × A. Schumannii Rehd.), azalea (Rhododendron obtusum Planch. ‘Tradition’) and Japanese holly (Ilex crenata Thunb.‘Helleri’) were evaluated in container studies. Experimental design was a randomized complete block with four replications and five containers of each species per plot. Root and shoot weights were recorded five weeks after either one, two or three herbicide applications. Ronstar (oxadiazon) and Ornamental Herbicide II [OH2 (oxyfluorfen plus pendimethalin)] had essentially no adverse effect on shoot or root development of the four species. Rout (oxyfluorfen plus oryzalin), Surflan (oryzalin), Gallery (isoxaben), and Factor (prodiamine) decreased root and/or shoot development of certain species, especially at the first two harvests. Plant size at treatment may be a factor in the extent of stunting caused by preemergence herbicides, with larger plants being more tolerant. Stunting of shoot and root growth appeared to be temporary.

Aluminum tolerance, mineral nutrition, and growth of 'Helleri' holly in solution culture

Abstract ‘Helleri’ holly (Ilex crenata Thunb. ‘Helleri') plants were grown in solution culture at aluminum (Al) concentrations of 0, 6, 12, 24, and 48 mg.L‐1 for 116 days. Aluminum did not affect root or crown index, stem length growth, plant dry weight, or leaf area. Aluminum treatments significantly increased Al uptake and reduced nutrient uptake of magnesium (Mg), calcium (Ca), zinc (Zn), and copper (Cu) on some sampling dates. Iron (Fe) and manganese (Mn) uptake decreased on most sampling dates but increased on some with Al treatments. Potassium (K), phosphorus (P), and boron (B) uptake were significantly affected by Al, decreasing and increasing at different sampling dates. Although plants preferentially took up ammonium‐nitrogen (NH4 +‐N) in all treatments (including 0 Al controls), neither NH4 +‐N nor nitrate‐nitrogen (NO3 ‐N) uptake were affected by Al. Tissue concentrations of P, K, B, Zn, and Al increased with Al treatment; whereas tissue Ca, Mg, and Cu concentrations decreased with increasing A...

WATER CONSERVATION IN CONTAINER PRODUCTION NURSERIES—IRRIGATION SCHEDULING

Applying only the amount of water needed by a plant, when it needs it, is a simple concept that can conserve water and reduce runoff. Simple, that is, when managing a single crop that covers an extensive area under several irrigation zones. Container production nurseries grow a large number of plants and each irrigation zone usually has a diverse grouping of taxa in various stages of development. In 1989, a nursery crop project at Oregon State University began to investigate irrigation scheduling for container-grown woody landscape plants. Crop coefficients (kc), used to adjust irrigation to specific production practices and crop characteristics, vary greatly for woody landscape plants. Woody plant kc values range from <1.0 to >5.0 during the production cycle. Plant taxa, growth stage, spacing, and pruning significantly influence kc of container-grown plants. Ilex crenata `Green Island' showed a reduction in water use (40%) immediately after pruning, but had similar kc values 60 days later. Grouping plants with similar kc values under the same irrigation zone is a very difficult task for a production nursery. It might be more practical to schedule irrigation for daily evapotranspiration, avoid placing new plantings next to mature crops, and only separate-out plants with very high or very low crop water requirements.

Plastic Bed Surface Decreases Water Drainage from Container-grown Plants

Growers report that plants on gravel bed surfaces require more frequent irrigation compared to plastic surfaces. The objective of Expt. 1 was to determine if bed surface type influenced container environment and plant growth of azalea and Japanese holly plants on plastic- or gravel-covered beds. Measurements included bed, substrate, and plant canopy temperatures; evapotranspiration (ET), stem water potential, and plant widths also were determined. The objective of Expt. 2 was to determine the amount of water retained following irrigation and drainage for four pre-irrigation substrate water contents (230%, 208%, 185%, 162%; mass basis) on gravel or plastic bed surfaces. Containers on plastic or gravel beds were irrigated, drained for 1 hour, and the amount of water retained in the container substrate was determined. In Expt. 1, plastic bed surface temperatures (0730 to 1930 hr) were higher than for gravel. Container substrate temperatures on plastic were 1°C higher than gravel from 2300 to 0400 hr with no temperature differences from 0500 to 2300 hr. There were no treatment differences for other characteristics. In Expt. 2, containers on plastic retained 21%, 15%, 23%, and 16% more water than on gravel for the 230%, 208%, 185%, 162% pre-irrigation water content treatments, respectively. When containers are seated on plastic, the bottom drainage hole is sealed resulting in more water retention compared to gravel.