bluuebunny/crossref_metadata_2025 huggingface dataset:
Growth Response and Mineral Uptake of Lettuce and Tomato Transplants Grown in Media Amended with Composted Sewage Sludge
Authors: Falahi-Ardakani A. , Bouwkamp J.C. , Gouin F.R. , Chaney R.L.
Published: August 2020

Lettuce, Lactuca sativa L. ‘Summer Bibb’ and tomato, Lycopersicon esculentum Mill. ‘Westover’ were grown 4 weeks in plastic market packs (MP) in 3 experimental media and a commercially available (Maryland Mix) control. The experimental media were prepared by combining equal parts, by volume of: 1) screened composted sewage sludge (CSS) (made from lime dewatered ferric chloride treated sewage sludge and wood chips), peat moss (PM), and perlite (PL) (CSS-PM-PL); 2) CSS, PM, and vermiculite (VL) (CSS-PM-VL); and 3) CSS-PL-VL. A commercially prepared medium, Maryland mix consisting of silt loam, peat, perlite, and vermiculite (1:2:1:1 by vol) was used as a control. The market packs containing 6 transplants each, were arranged in a completely randomized design and replicated 4 times. One set of seedlings were grown in Maryland mix and CSS-PM-PL and fertilized at the end of the 1st, 2nd, and 3rd week after transplanting with a commerical 20N-8.6P-16.6K (20-20-20) fertilizer. Another set of seedlings were grown for 4 weeks in the control mix and 3 experimental media and fertilized at 1st and 3rd week after transplanting with only N fertilizer.

For both lettuce and tomato plants, only 270 mg of N per MP per growing period produced marketable size transplants when grown in the CSS-PM-VL medium. These seedlings had no toxic levels of Zn, Cd, Pb, and Ni and contained adequate N, P, K, Ca, Mg, Mn, Fe, and Cu as compared to plants grown in the control medium.
Effect of Hydrophylic Polymer Amendment on Growth of Container Grown Landscape Plants
Authors: Keever G.J. , Cobb G.S. , Stephenson J.C. , Foster W.J.
Published: August 2020

Four experiments were conducted over 3 years to determine the influence of a water-absorbing polymer (hydrogel), Mizuace4, on the growth of container grown landscape plants. Amending the 100% pine bark growth medium with 0,0.9, 1.8, 2.7, or 3.6 kg/m3 (0, 1.5, 3.0, 4.5, 6.0 lb/yd3) hydrogel did not affect irrigation frequency. Foliar and growth medium nutrient levels were minimally affected, and shoot and root growth were reduced or not affected by increasing rates of hydrogel.
Chemical Growth Retardants Increase Seed Yield in Apple Trees
Authors: Struve Daniel K. , Miller Diane Doud , Ferree David C.
Published: August 2020

In two experiments the effects of trunk drenches with two gibberellin biosynthesis inhibitors on vegetative growth, seed yield and quality of ‘Delicious’ and ‘Golden Delicious’ apple trees were studied. In the first experiment trunk drenches of either paclobutrazol or uniconizole were applied to ‘Golden Delicious’ apple trees in spring 1984. Both chemicals significantly reduced shoot length in 1985 and 1986. In 1986, fruit number tended to be higher in treated trees, but was less than untreated trees in 1985 and 1984. The estimated number of sound seeds produced in 1986 on treated trees was increased. Neither chemical significantly affected seed quality or seedling growth. In a second similar experiment paclobutrazol, applied as a trunk drench in spring 1984 at rates of 2, 4 or 8 g active ingredient (ai)/tree, significantly reduced shoot growth in 1985 and 1986. The number of sound seed/tree was significantly increased in 1986 at all paclobutrazol levels due to an increase in the number of fruit/tree. Paclobutrazol application had no effect on seed quality, rate of germination, final percent germination, or on seedling growth. Potentially, both compounds could be used to control vegetative growth without affecting seed yield or quality in deciduous seed orchards.
Using a Programmable Calculator for Determining Potential Evapotranspiration Rates
Authors: Fitzpatrick George E. , Verkade Stephen D.
Published: August 2020

A program is presented allowing the computation of uncorrected potential evapotranspiration (ETp) rates using a low-cost (<$50) hand-held programmable calculator. This program requires the user to supply average local or on-site monthly temperatures. The first part of the program computes the annual heat index and the exponent necessary for ETp determination. The second part of the program computes monthly ETp rates by the Thornthwaite procedure as each average monthly temperature is keyed in. Comparisons of computed ETp rates with measured actual evapotranspiration (ETa) rates of various container-grown nursery crops show good correlation.
Space Allocation in Foliage Production Greenhouses
Authors: Krafka Brenda D.L. , Richard Shumway C. , Reed David W.
Published: August 2020

A profit-maximizing linear programming model of a typical Rio Grande Valley foliage plant operation was developed to allocate finish-house space among alternative combinations of plants. This model accounted for seasonal changes in both market prices and growth rates of foliage plants. It was written to permit solution by microcomputer. The model may also aid foliage producers in making marketing and capital budgeting decisions by providing marginal revenue and cost estimates under varying crop rotations and product mixes.
Response of Ligustrum × ibolium, Photinia × fraseri, and Pyracantha koidzumii ‘Wonderberry’ to XE-1019 and Pruning
Authors: Norcini Jeffrey G. , Knox Gary W.
Published: August 2020

The use of XE-1019 (uniconazole) [(E)-1-(4-chlorophenyl)-4, 4-dimethyl-2-(1,2,4-triazol-1-yl)-1-penten-3-ol] was investigated as an alternative to pruning of container-grown Ligustrum × ibolium, Photinia × fraseri, and Pyracantha koidzumii ‘Wonderberry’. A soil drench of 2.5, 5.0 or 10.0 mg/plant (in 100 ml tap water) was applied to unpruned and pruned plants on September 19, 1986. XE-1019 reduced plant growth, primarily through a reduction in plant height. Plants pruned at the time XE-1019 was applied had more desirable growth habits than unpruned growth-regulated plants. The maximum level of XE-1019 which caused acceptable growth retardation of Photinia was 5.0 mg/plant. A soil drench of 2.5 mg/plant resulted in excessive growth reduction of Ligustrum and Pyracantha.
Propagation of Osmanthus heterophyllus ‘llicifolius’ and ‘Rotundifolius’ by Stem Cuttings
Authors: Blazich Frank A. , Acedo Juan R.
Published: August 2020

Nontreated semihardwood and hardwood cuttings of Osmanthus heterophyllus ‘Ilicifolius’ rooted in high percentages (>80%) while comparable results for ‘Rotundifolius’ were only noted for hardwood cuttings. Response of both cultivars to indolebutyric acid (IBA) treatment [2500 to 10,000 ppm (0.25 to 1.0%)] was variable and often resulted in inhibition rather than stimulation of rooting.
Field Evaluation of Preemergence Herbicides for Weed Control In Container Grown Woody Landscape Plants
Authors: Duray Sharon A. , Davies Fred T.
Published: August 2020

Four preemergence herbicide combinations were evaluated for weed control and phytotoxicity on Silverberry (Elaeagnus pungens Thunb.), Spanish bayonet (Yucca aloifolia L.), and Heavenly bamboo (Nandina domestica Thunb.), grown in 3.8 1 (1 gal) containers under commercial nursery conditions. Combinations of Rout (oxytluorfen : oryzalin) and Rout GL (oxytluorfen : alachlor) were applied as granules at 1.12 : 0.56, 2.24 : 1.12 and 4.48 : 2.24 and 1.12 : 1.12, 2.24 : 2.24, and 4.48 : 4.48 kg ai/ha (1.0 : 05, 2.0 : 1.0, and 4.0 : 2.0 and 1.0 : 1.0, 2.0 : 2.0 and 4.0 : 4.0 lb ai/A), resp. Harness (acetochlor) was applied as a foliar spray at 1.68, 3.36 and 6.68 kg ai/ha (1.5, 3.0 and 6.0 lb ai/A) and Zorial (norflurazon) was applied at 1.12, 2.24 and 4.48 kg ai/ha (1.0, 2.0 and 4.0 lb ai/A) as a soil drench. Containers were overseeded with a weed mixture prior to herbicide application and six weeks later to induce extreme weed competition in containers. Harness, Rout GL and Rout provided 90–100% control for up to 14 weeks after application at the highest rates evaluated. Zorial resulted in unsatisfactory weed control. None of the herbicides caused any phytotoxic effects on any of the plants tested.
Influence of Mulches on Weed Control, Soil pH, Soil Nitrogen Content, and Growth of Ligustrum japonicum
Authors: Billeaud Lorraine A. , Zajicek Jayne M.
Published: August 2020

Four organic mulches, screened pinebark, hardwood (primarily oak), cypress and decorative pinebark nuggets, applied at depths of 0, 5, 10, and 15 cm (0, 2, 4, 6 in) with or without an inorganic weed barrier fabric, were tested in field and container studies to determine their effect on weed suppression, soil pH, soil nitrogen content, and growth of Ligustrum japonicum. Results indicated that mulch applied at shallower depths, in combination with a weed barrier, provided optimal weed control without tying up soil nitrogen or reducing plant growth. Coarser mulches out-performed finer-textured materials. Most effective weed control was obtained with decorative pinebark nuggets with weed barrier fabric at a 15 cm (6 in) depth of application when compared to unmulched controls. As the depth of mulch was increased, soil pH, soil nitrogen content, and visual rating of plant growth decreased. Mulches over 10 cm (4 in) deep tended to inhibit plant growth, although optimum depth was dependent on the mulch material used.
Root and Shoot Growth Response of Three Container-Grown Kalmia latifolia L. Cultivars at Two Locations to Growing Medium and Nitrogen Form
Authors: Hummel Rita L. , Johnson Charles R. , Lindstrom Orville M.
Published: August 2020

Rooted liners of Kalmia latifolia L. ‘Elf’, ‘Freckles’ and ‘Goodrich’ were shipped to Griffin, Georgia, and Puyallup, Washington and were potted into 3.8 liter (# 1) containers. Factorial combinations of growing media (1 bark: 1 peat, 4 bark: 1 peat), NO3/NH4 ratios (100% NO3/0% NH4, 60% NO3/40% NH4, 20% NO3/80% NH4), and rates of N (40, 80, and 120 mg N/pot; 0.0014, 0.0028, and 0.0042 oz N/pot, resp.) were applied at both locations. Results indicated that a combination of the nitrate/ammonium forms of nitrogen (60/40 NO3/NH4) and the 80 mg/pot N rate produced the best overall shoot and root growth on all 3 cultivars at both locations. Root and shoot growth was not affected by growing media at either location. With the exception of lower pH readings for the Georgia media, results for the two locations were remarkably consistent.
Evaluation of Composted Rice Hulls and a Lightweight Clay Aggregate as Components of Container-Plant Growth Media
Authors: Laiche Adolph J. , Nash V. E.
Published: August 2020

Four experiments were conducted with selected woody landscape plants in containers to compare container media consisting of composted rice hulls and a lightweight clay aggregate (Arkalite) to pine bark and sand. Plant growth in the inorganic components of sand and Arkalite was generally similar. Plant growth in organic components of 100% composted rice hulls or 50% composted rice hulls and 50% pine bark compared favorably with the growth obtained with 100% pine bark as the organic component. Excellent growth was obtained with composted rice hulls only when not amended or amended with small amounts of dolomitic limestone. Use of composted rice hulls should be based on costs and availability.
Effects of P-ITB and IBA on the Rooting Response of 19 Landscape Taxa
Authors: Dirr Michael A.
Published: August 2020

A new root promoting chemical, P-ITB (phenyl indole-3-thiolobutyrate) was compared with IBA (1H-indole-3-butanoic acid) for activity on 19 woody taxa. P-ITB at 0.5% was as effective as 0.5% IBA for the plants tested. For difficult-to-root taxa like Amelanchier arborea, Photinia × fraseri and Zelkova serrata, P-ITB promoted excellent rooting. The chemical is as effective as IBA and was not injurious at the 2.0% level.
Control of Rust of China Aster and Comments on the Name of the Pathogen
Authors: Raabe Robert D. , Pyeatt Lyle
Published: August 2020

Rust, Coleosporium asterum, of China aster, Callistephus chinensis, is a serious problem on plants grown for cut flowers in California. Control of the rust resulted from 3 applications of fungicides at 3-week intervals. Funginex® (triforine) gave the best control. Bayleton® (triadimefon) and Fore® (mancozeb) gave good control. Plantvax® (oxycarboxin) and Physan® (a quanternary ammonium chloride compound) failed to control the fungus satisfactorily. The use of the binomial Coleosporium asterum, formerly called C. solidaginis, is questioned.
Screening of Odor and Taste Repellents for Control of White-tailed Deer Browse to Apples or Apple Shoots
Authors: Byers R.E. , Carbaugh D.H. , Presley C.N.
Published: August 2020

A rapid method was developed for evaluating deer repellents using apples or apple shoots were placed on 1 m (3.3 ft) stakes in a highly populated white-tailed deer area. Big Game Repellent (BGR, Putrescent whole egg solids (37%)), Hot Sauce (Capsaicin (2.5%)), and Lifebouy soap (scented or unscented) were the most effective repellents, but they repelled deer for only very short periods of time (1 to 6 days). The perfume from Lifebuoy soap also showed some repellency. Dilution of any of the repellents reduced their effectiveness for inhibiting deer browse. Deer readily accepted apples placed on stakes, but they would not touch broccoli heads.
Growth and Root Penetration by Large Crabgrass and Bermudagrass Through Mulch and Fabric Barriers
Authors: Appleton Bonnie Lee , Derr Jeffrey F.
Published: August 2020

Four polypropylene fabrics and five polyethylene (plastic) films, covered with shredded pinebark mulch, were compared for suppression of large crabgrass (Digitaria sanguinalis (L.) Scop.) and bermudagrass (Cynodon dactylon (L.) Pers.) shoot and root growth, and root penetration. No covering completely controlled either grass, but significant differences existed between materials, with Weed-X giving the best overall shoot suppression. Penetration of both grasses' roots was less through Weed-X, Weed Control and brown polyethylene than through Weed Barrier, Duon, Typar, WeedBlock, Magic Mat and Weedstop. Weed growth in the mulch layers atop the fabrics and films are significant. Resistance to weed root penetration was possibly related to the percent of open versus closed areas of the fabrics and films. Fabrics or perforated films with greater root penetration resistance should generally provide greater overall landscape weed control than those allowing greater root penetration.
Weed Control In Field-Grown Holly
Authors: Wehtje Glenn , Gilliam Charles H.
Published: August 2020

Two separate experiments were conducted over a 3-year growing period to examine control of grass and broadleaf weeds in three cultivars of Ilex. The effect of application timing and number of applications of a tank mixture of Surflan (oryzalin) + Princep (simazine) [2.2 + 0.9 kg ai/ha (2.0 + 0.75 lb ai/A)] were examined in the first study. Maximum season-long control was obtained with any treatment that contained a minimum of two herbicide applications, with the first applied in March and the second in July. The performance of various 2-way combinations of Surflan, Princep and Goal was examined in the second experiment. Acceptable weed control was obtained with any combination that contained broadleaf and grass-active herbicides. Inspection of data across both studies indicates that timing of application is of greater importance than the specific herbicides used.
Tolerance of Selected Tree Seed to Combinations of Preemergent Herbicides
Authors: Geyer W. A. , Long C. E.
Published: August 2020

Black locust (Robinia pseudoacacia L.), honey locust (Gleditsia triacanthos L.), and Kentucky coffee tree (Gymnocladus dioica (L.) C. Koch) seed were planted in soil treated with various combinations of preemergent herbicides and grown in the greenhouse to determine herbicide effect on seedling survival and growth. Herbicides evaluated included Lasso (alachlor) alone at 2.2 a.i. kg/ha (2.0 a.i. lb/a), and in combination with Lorox (linuron) 1. 7 (1.5), Surflan (oryzalin) 2.2 (2.0), or Dacthal (DCPA) at 11.8 (10.5); Surflan (oryzalin) alone at 2.2 (2.0) and in combination with Dacthal (DCPA) 11.8 (10.5) or Lorox (linuron) 1.7 (1.5); Dacthal (DCPA) alone at 11.8 (10.5) and in combination with Lorox (linuron) 1.7 (1.5); and Lorox (linuron) at either 1.7 (1.5) or 3.3 (3.0). All treatment were acceptable on Kentucky coffee tree seed. Lasso (alachlor) or Dacthal (DCPA) alone or mixed together and applied to honey locust or black locust were acceptable in respect to height and/or dry weight growth. All other treatments were damaging to these two species.
Seed Germination of Leucothoe fontanesiana as Influenced by Light and Temperature
Authors: Blazich Frank A. , Warren Stuart L. , Acedo Juan R. , Whitehead Reid O.
Published: August 2020

Seeds of Leucothoe fontanesiana (Steud.) Sleum. were germinated at 25°C (77°F) and 25°/15°C (77°/59°F) with daily photoperiods of 0, 1/2, 1/2 twice daily, 1, 2, 4, 8, 12, or 24 hr. For both temperatures, no germination occurred during a 30-day period for seeds not subjected to light. At 25°C (77°F) increasing photoperiods increased germination with germination of 60 and 68% occurring by day 24 for the 12 and 24 hr photoperiods, respectively. The alternating temperature of 25°/15°C (77°/59°F) enhanced germination when light was limiting. At this temperature germination ≥85% was reached by day 27 for photoperiods ≥2 hr.
Buyer Perceptions of Foliage Trade Shows: Implications for Marketing
Authors: Haydu John J. , Meerow Alan W. , Sitaras Gina
Published: August 2020

A ten question survey was mailed to all registered buyers of the 1988 Foliage Expo trade show in Hallandale, Florida to seek their opinions on the performance of the show, to better understand the buyer profile, and gain insight into the effectiveness of these shows as marketing tools. Based on the results of this survey, it appears that an important target group, namely the retail trade sector, were not being drawn in sufficient numbers to this particular trade show. These findings indicate that sponsors may not have clearly identified the intended audience, determined unambiguously the preferences of this audience, nor effectively advertised and promoted the trade exhibition.
Effect of the Amount of Dormant Pruning on Growth and Water Use of Containerized Crape Myrtle (Lagerstroemia × Fauriei ‘Tuscarora’)
Authors: Zajicek Jayne M. , Steinberg Susan L. , McFarland M.J.
Published: August 2020

A study was conducted to determine the effects of different dormant pruning treatments on subsequent plant development and water use of crape myrtle (Lagerstroemia × Fauriei Koehne ‘Tuscarora’) transplanted into containers. Dormant, bare-root plants were pruned to the normal practice of a 30% reduction of existing shoot length by heading back and thinning of weak branches. Plants were randomly assigned to 3 pruning treatments including: 1) control—no further pruning, 2) shoot pruned—an additional 50% reduction of remaining shoot length for a total of 65% reduction in shoot length, or 3) a 50% reduction of root area in addition to the 30% reduction in shoot length. Fifty percent (50%) root pruning severely reduced earliness of bud-break and plant survival when compared to either the control or the 65% shoot pruning treatments. Earliest bud-break and highest plant survival were rated for plants in the 65% shoot pruned treatment. Plants in the 50% root pruned treatment had a significantly higher number of terminal shoots, but average shoot lengths were significantly shorter when compared to plants in the 65% shoot pruned treatment. At final harvest there were no significant differences in mean dry weights and leaf area, total shoot length, or average water use between treatments. However, a large plant to plant variation in growth and water use due to the pruning treatments was observed. Plants in the 50% root pruned treatment were less uniform in size and water use as compared to control plants or 65% shoot pruned plants which exhibited the greatest uniformity.
Manganese Binding by Municipal Waste Composts Used as Potting Media
Authors: Broschat Timothy K.
Published: August 2020

Queen palms (Syagrus romanzoffiana (Chamisso) Glassman) grown in several types of sewage sludge compost media developed severe Mn deficiency symptoms. Seventy of the symptoms was correlated with DTPA-extractable Mn levels in the media and with leaf Mn content, but not with total media Mn. Compost media tied up over 70% of Mn added to samples within one hour, versus 62% or less for a pine bark, sedge peat, and sand medium. Analysis of autoclaved media samples suggested that some of the Mn tie up in garbage and yard trash composts is caused by microorganisms, but microorganisms had little effect on the binding potential of sludge and manure composts.
Growth Habit of Weigela florida as Affected by Stock Plant Propagation History
Authors: Ghrist Angela C. , Stephens Loren C. , Weigle Jack L.
Published: August 2020

The effects of stock plant propagation history on the growth habits of Weigela florida (Bunge) A.D.C. ‘Red Prince’ and ‘7755’ were investigated. The growth habits of cuttings from tissue culture (TC)-propagated and conventionally (CV) propagated plants were compared. In the first vegetative generation, TC-propagated plants of both cultivars exhibited reduced apical dominance and increased branching in comparison with CV propagated plants. In the second vegetative generation, some of the effects of TC-propagation persisted in plants of both cultivars, although TC-propagated plants exhibited fewer differences in growth habit as compared with CV propagated plants. The results of this study indicate that TC-derived stock plants and first-vegetative-generation TC-propagated plants may serve as superior sources of propagation material by providing an increase in both the quantity and quality of cuttings that they produce.
Evaluation of Six Herbicides for Potential Use in Tree Seed Beds
Authors: Warren S.L. , Skroch W.A.
Published: August 2020

Five herbicides, Pennant, Surflan, Devrinol, Ornamental Herbicide 2, and Ronstar, were applied over newly seeded deciduous trees immediately after seeding and Poast was applied when seedlings were actively growing. The trees were river birch, pin oak, willow oak, redbud, flowering dogwood, sugar maple, and sweet gum. No seedlings were damaged by Pennant (4.5 kg/ha) or Poast. Ornamental Herbicide 2 and Ronstar severely damaged river birch, flowering dogwood, and sugar maple. Surflan damaged sugar maple. Devrinol damaged flowering dogwood. Data herein suggest that each species must be evaluated separately for herbicide tolerance.
Rodenticides for the Control of Pine and Meadow Voles in Orchards
Authors: Byers Ross E. , Carbaugh David H.
Published: August 2020

Two new anticoagulants (bromadiolone—90% control) and (difethialone—87% control) gave excellent control of voles in field and laboratory tests. The older anticoagulants, chlorophacinone—84% control and diphacinone—75% control, and two zinc phosphide formulations (Bell Labs—84% control and Hopkins—79% control) also gave excellent field control of voles. The Ridall zinc phosphide formulation—61% control, and cholecalciferol (vitamin D3)—59% control did not perform as well as the other rodenticides previously mentioned. The antibiotic, oxytetracycline, killed from 40% to 80% of pine and meadow voles in laboratory trials when applied to cut apples, but only 10 to 30% when pelletized baits were presented. In a mixed pine and meadow vole orchard population, zinc phosphide raised the ratio of surviving pine to meadow voles while anticoagulants lowered the ratio. Thus, the rotation of rodenticides is thought to be desirable to prevent the shift of one species to the other in mixed populations and to prevent bait shyness from developing to zinc phosphide.
Estimating Visitor Use-Value of Arboreta: The Case of the University of Tennessee Arboretum2
Authors: Downing Mark , Roberts Roland K.
Published: August 2020

Many studies have estimated demand functions for visits to recreation sites. Several included commonly defined recreation-based areas such as beaches, parks, lakes and rivers, but excluded examination of horticulturally significant sites such as botanic gardens and arboreta. This study estimates user-demand and consumer surplus for visits to the University of Tennessee Arboretum by the travel cost method. Results suggest that travel cost and income of consumers are important determinants of demand, at least in the case of visits to the University of Tennessee Arboretum, and that consumer-use value may be derived from this demand. Consumer-use value is estimated to be $20.43 per person.
Leaf Gas Exchange of Eastern Redbud (Cercis canadensis L.) Grown Under Sun and Shade
Authors: Norcini Jeffrey G. , Knox Gary W. , Andersen Peter C.
Published: August 2020

Leaf physiology of eastern redbud (Cercis canadensis L.) was assessed under natural photoperiod when grown in 100% sun or under polyethylene shade with a light transmittance of 69%, 47%, or 29% sun. Net CO2 assimilation rate (A) was similar under 100%, 69%, and 47% sun; A was reduced under 29% sun. Adaptations to shade included a near perpendicular leaf orientation to the sun, reduction in specific leaf weight (SLW), and a decreased chlorophyll a: chlorophyll b ratio. Conversely, eastern redbud adapted to 100% sun by manifesting an increased SLW and a vertical orientation of leaves that curled inward toward the midrib. Light response curves were similar for sun- and shade-acclimatized plants. When all data were analyzed collectively, A was most closely related to photosynthetic photon flux (PPF) (R2 = 0.52), whereas stomatal conductance to water vapor (gs) was primarily influenced by vapor pressure deficit (VPD) (R2 = 0.75). Hence, A and gs were not well correlated (R2 = 0.41). The lack of strong coupling between A and gs allowed the stomates to remain open under low PPF, resulting in an elevated intercellular CO2 concentration. Thus, A was stimulated above what might have normally occurred under low PPF.
BMP Assessments Using CCROP (Container Crop Resource Optimization Program) Simulation Tools
Authors: Million Jeff B. , Yeager Thomas H.
Published: August 2020

We describe and demonstrate the use of web-based simulation tools that use the plant growth model CCROP (Container Crop Resource Optimization Program) to quantify the expected impacts that two example best management practices (BMP) would have on water and N use during production of a container-grown woody ornamental plant. For Example 1, an irrigation BMP of applying amounts of water proportional to plant demand (evapotranspiration) was compared to fixed irrigation rates of 1.0 and 1.5 cm·d−1 at two locations in Florida and for six planting dates. For Example 2, a fertilizer BMP of customizing controlled-release fertilizer N rates based on expected N response was compared to a single N rate that resulted in optimal growth for six plant dates. Simulations based on eight years of historical weather data projected that the irrigation BMP would reduce water usage 24–57% with greater savings coinciding with longer crop times as affected by planting date and location. Similarly, simulations projected that the fertilizer BMP would reduce controlled-release fertilizer N applied 15–37% depending upon container size and planting date. Simulation tools also estimated cost savings and reduced environmental impact (N leaching loss) resulting from BMPs. We concluded that CCROP simulation tools can help growers and grower-advisers quantify potential impacts so that informed, economic decisions regarding BMP implementation can be made which are applicable to management practices and weather at the container nursery.
Interploid Hybridizations in Ornamental Cherries Using Prunus maackii
Authors: Pooler Margaret , Ma Hongmei , Kidwell-Slak David
Published: August 2020

The United States National Arboretum has an ongoing flowering cherry (Prunus) breeding program aimed at broadening the genetic base of cultivated ornamental cherries by developing new cultivars with disease and pest resistance, tolerance to environmental stresses, and superior ornamental characteristics. Interploid crosses, specifically 2X × 4X, in ornamental Prunus would be beneficial in breeding because they could allow introgression of traits not available in the diploid germplasm (pest resistance, cold hardiness), and could result in the creation of seedless triploids that would not set nuisance fruit and possibly have extended bloom durations. This report documents successful hybridization of P. maackii (Manchurian or Amur cherry), a tetraploid species, with P. campanulata, P. ‘Umineko’, and P. maximowiczii, all diploid species. Chromosomes of one of these resulting triploid hybrids were successfully doubled using oryzalin in tissue culture to create a hexaploid plant.
Determining Trace Gas Efflux from Container Production of Woody Nursery Crops
Authors: Marble S. Christopher , Prior Stephen A. , Runion G. Brett , Torbert H. Allen , Gilliam Charles H. , Fain Glenn B. , Sibley Jeff L. , Knight Patricia R.
Published: August 2020

Agriculture is a large contributor of trace gas emissions and much of the work on reducing greenhouse gas (GHG) emissions has focused on row crops and pastures, as well as forestry and animal production systems; however, little emphasis has been placed on specialty crop industries such as horticulture. Our objective was to determine efflux patterns of CO2, CH4, and N2O associated with four different nursery container sizes [3.0 liter (trade gal; TG), 3.8 liter (#1; 1 gal), 7.6 liter (#2; 2 gal), and 11.4 liter (#3; 3 gal) using dwarf yaupon holly (Ilex vomitoria ‘Nana’ L.) grown under common production practices for one year. Weekly measurements indicated that carbon dioxide (CO2) and nitrous oxide (N2O) fluxes were highest in the largest containers (#3). There was a significant positive relationship between container size and CO2 efflux. Nitrous oxide efflux followed a similar pattern, except there were no differences between the two smallest container sizes. In general, CO2 and N2O fluxes increased with increasing temperature. Methane flux was consistently low and had no significant effect on total trace gas emissions. Results from this study begin to address uncertainties regarding the environmental impact of the horticulture industry on climate change while providing baseline data of trace gas emissions from container production systems needed to develop future mitigation strategies.
Evaluating a Natural Zeolite as an Amendment for Extensive Green Roof Substrate
Authors: Bousselot Jennifer M. , Klett James E. , Koski Ronda D.
Published: August 2020

This research examined soilless green roof substrate blends on an existing modular extensive green roof in Denver, Colorado, USA. Substrate blends evaluated include an extensive green roof substrate, Green Grid® and Green Grid® plus varying percentages of ZeoPro™ H-Plus. Plant taxa used included Sedum acre L., Sedum album L., Sedum spurium Marsch-Bieb. ‘Dragon's Blood’ and S. spurium ‘John Creech’. Substrate blends were evaluated based on plant taxa growth performance. Data collected included digital images to measure plant area covered using digital image analysis (DIA) and substrate volumetric moisture content (VMC). All data were analyzed over two growing seasons using the GLIMMIX procedure in SAS as multiple comparisons of substrate blends for each taxa, DIA data were analyzed from eight dates and VMC data were analysed from seven dates. The addition of zeolite (ZeoPro™) to the typical extensive green roof substrate improved establishment year plant cover for S. acre and S. album but hindered overwintering. Conversely, the two cultivars of S. spurium did not show a benefit of plant cover from the addition of ZeoPro™ in the first year but did the second year. As the percentage of ZeoPro™ in the substrate increased, VMC also increased.
Effect of Phosphorus Concentration on Growth of Muhlenbergia capillaris in Flooded and Non-Flooded Conditions
Authors: Christian Kathryne J. , Wright Amy N. , Sibley Jeff L. , Brantley Eve F. , Howe Julie A. , Dougherty Mark P. , LeBleu Charlene M.
Published: August 2020

Research was conducted to evaluate the effect of phosphorus (P) concentration in irrigation water on growth of a southeastern U.S. native grass Muhlenbergia capillaris in flooded and non-flooded conditions. Plants of Muhlenbergia capillaris (Lam.) Trin. (gulf muhly grass) growing in 3.8 liter (1 gal) containers in 85:15 sand:peat were flooded to the substrate surface for 0 (non-flooded) or 3 days (flooded). Between flooding events, plants were drained for 6 d with no additional irrigation. The flood-drain process was repeated five times. Non-flooded plants were hand watered as needed. Plants were irrigated (non-flooded) or flooded with one of several tap water solutions, each with a different P concentration ranging from 0 to 0.8 mg·liter−1 (ppm) P (hereafter referred to as P irrigation rate). The experiment was repeated once (total two runs). Shoot dry weight (SDW) root dry weight (RDW) were higher in non-flooded plants than in flooded plants in both runs. Shoot dry weight increased linearly with an increasing P irrigation rate, while RDW changed cubically with increasing P irrigation rates in run 1 (no effect on either in run 2). Phosphorus concentration in leachate increased with increasing P irrigation rate in run 1 but not in run 2. Phosphorus concentration in leachate was usually higher in flooded plants than in non-flooded plants in both runs. All plants maintained root and shoot growth when flooded suggesting M. capillaris would be appropriate native species for rain gardens or bioretention areas. Phosphorus concentrations in leachate were lower than what was applied indicating P was removed via plant uptake or substrate adsorption or both.
Impact of Augeo, Configure and Florel on Hydrangea Branching
Authors: Hester K.A. , Bi G. , Czarnota M.A. , Fulcher A. , Keever G.J. , Lieth J.H. , Orsi J.D. , Whipker B.E. , Sullivan K. , Palmer C.L.
Published: August 2020

Hydrangeas are an increasingly popular group of shrubs which are prized for their showy inflorescence. Nursery crop producers grow numerous hydrangea varieties for the landscape and florist markets. Hydrangeas are typically hand-pruned during propagation and production to promote compaction and to increase the number of branches which has potential for increasing blooms and marketability. Identifying a plant growth regulator (PGR) treatment that effectively improves the architecture of hydrangeas became an IR-4 Project research priority for 2011. Research evaluating Augeo (dikegulac sodium), Configure (benzyladenine) and Florel (ethephon) shows worthwhile results. Augeo (800 and 1600 ppm) significantly increased branching compared to untreated pots of florist varieties Hydrangea macrophylla ‘Merritt's Supreme’ and landscape varieties H. macrophylla ‘Nikko Blue’ and H. paniculata ‘Limelight’. Configure (300 ppm and 600 ppm) and Florel (500 and 1000 ppm) did not significantly improve branching in five of six trials compared to the control. Significant chlorosis on Augeo treated plants was observed initially but this diminished by 6 weeks after treatment (WAT) for four out of six trials. Little to no crop injury was observed with Configure or Florel treatments to hydrangea liners. This research shows promise for identifying a plant growth regulator treatment to meet the demand for improved branching on hydrangea.
The Importance of Geographic and Biological Variables in Predicting the Naturalization of Non-Native Woody Plants in the Upper Midwest
Authors: Widrlechner Mark P. , Kapler Emily J. , Dixon Philip M. , Thompson Janette R.
Published: August 2020

The selection, introduction, and cultivation of non-native woody plants beyond their native ranges can have great benefits, but also unintended consequences. Among these consequences is the tendency for some species to naturalize and become invasive pests in new environments to which they were introduced. In lieu of lengthy and costly field trials, risk-assessment models can be used to predict the likelihood of naturalization. We compared the relative performance of five established risk-assessment models on species datasets from two previously untested areas: southern Minnesota and northern Missouri. Model classification rates ranged from 64.2 to 90.5%, biologically significant errors ranged from 4.4 to 9.3%, and horticulturally limiting errors ranged from 6.6 to 30.4%. For the random forest model, we investigated the importance of variables used to predict naturalization by examining datasets for five distinct study areas across the Upper Midwest. Geographic-risk ratios were the most important predictors of species' tendency to naturalize. Other factors, such as quick maturity, record of invading elsewhere, and production of fleshy, bird-dispersed fruit were also important in the random forest models. Although some models tested need additional refinement, the random forest models maintain robustness and provide additional information on plant-specific characteristics that contribute to naturalization.
Defining a Protocol for Vegetative Propagation of Baptisia, Eupatorium and Thermopsis
Authors: Hawkins Susan M. , Chappell Matthew , Martin Michael T.
Published: August 2020

We determined that highly successful vegetative propagation is possible for Baptisia, Thermopsis and Eupatorium. This is significant because vegetative propagation of these native genera has not been widely practiced in commercial ornamental production. Seed propagation has been utilized over vegetative propagation due to historically low rooting percentages and reduced crowning (bud formation at the root-shoot union) when vegetative propagation is employed. However, vegetative propagation can enable the production of ornamental nursery stock quicker and with greater uniformity in finishing time compared to seed propagation. Vegetative propagation can also facilitate the perpetuation of threatened or endangered species that have small or isolated populations (limited sexual reproduction) or can be used to build numbers of phenotypically superior individuals without wild digging. Four model species representing three native herbaceous genera that include multiple threatened or endangered species were used in the study. Four concentrations of K-IBA (potassium salt of Indole-3-butyric acid) were examined along with 28 and 56 days in a propagation environment to determine the best rooting percentage and root quality for each species. An economic analysis was conducted to test the efficacy of treatment with K-IBA versus double-sticking two untreated cuttings. In addition to developing a commercially viable propagation protocol for these three species, we also determined that treatment with K-IBA is not necessary for successful propagation of the majority of these species, but that more time in a commercial propagation environment leads to higher rooting percentages at a reduced propagation cost.
Off-Target Injury to Southern Landscape Species Following Aminocyclopyrachlor Applications
Authors: Wherley Benjamin , Pannkuk Tim , Cabrera Raul I. , Campos Carlos
Published: August 2020

Aminocyclopyrachlor is an herbicide for broadleaf weed control that has recently come under scrutiny following reports of injury to landscape ornamentals across the upper Midwestern United States. This herbicide has been shown to provide excellent weed control in warm-season turfgrasses at much lower use rates than that used for cool-season turf, but data are lacking concerning its safety to landscape ornamentals in southern U.S. regions. Parallel studies were conducted in Dallas and Huntsville, TX, locations to evaluate off-target injury effects on sixteen ornamentals and trees commonly used in southern landscapes. In March 2012, just prior to the spring growth flush, aminocyclopyrachlor was applied to potted plants at 0, 0.5, 1, 2, or 4× rates as either as granular [0, 14, 28, 56, or 112 g ai·ha−1 (0.013, 0.03, 0.05, and 0.10 lbs ai·A−1)] or liquid [0, 11.2, 22.4, 44.8, or 89.6 g ai·ha−1 (0.01, 0.02, 0.04, 0.08 lbs ai·A−1)] formulations. For the next 8 weeks, plants were evaluated for injury to new growth. Injury was observed in 9 of the 16 species used, but was generally mild to moderate in nature. Species exhibiting the greatest sensitivity to aminocyclopyrachlor included loblolly pine (Pinus taeda), viburnum (Viburnum odoratissimum), nandina (Nandina domestica ‘Compacta’), and camellia (Camellia japonica). Extent of injury was not different between granular or liquid formulations, but was less severe at the Dallas location. Results of the study indicate sensitivity within some southern landscape ornamentals to aminocyclopyrachlor.
Seasonal Activity, Within-Tree Distribution, and Ovipositional and Feeding Preference of the Elm Leafminer, Fenusa ulmi (Hymenoptera: Tenthredinidae)
Authors: Miller Fredric , Ware George
Published: August 2020

Seventy-six different elm taxa were visually rated for elm leafminer (Fenusa ulmi Sundevall) defoliation. European elm taxa were more found to be more susceptible to feeding damage by the elm leafminer compared to Asian and North American elm taxa. European elms U. glabra, U. elliptica, U. sukaczezii, and elms with U. glabra-wallichiana parentage were highly susceptible to elm leafminer leaf feeding damage. Of the 37 Asian elm taxa evaluated, only U. laciniata was highly susceptible to feeding damage. The North American species U. rubra was the only North American elm susceptible to elm leafminer feeding. Adult emergence, initial leafmining, and cessation of leafmining were highly correlated with indicator plant full bloom phenology providing an accurate degree-day (DD) model for practitioners in predicting and monitoring for elm leafminer life stage development and related plant damage. Elm leafing out phenology of susceptible European elms was highly correlated with elm leafminer adult emergence and oviposition. Less susceptible European elm taxa, such as U. procera, and U. carpinifolia and cultivars, consistently leaf out later after peak adult leafminer emergence. Interestingly, the majority of Asian elm taxa such as U. davidiana, U. japonica, U. lamellosa, and U. pumila leaf out at the same time as susceptible elm taxa, but experience no or negligible feeding damage. Two Asian species, U. wilsoniana and U. parvifolia, leaf out later after peak adult emergence and oviposition has passed. No consistent pattern was observed for within tree ovipositional wounds and subsequent leafminer feeding damage for tree height or cardinal direction for both small and large elm tree species. Results from this study indicate there is a large number of Asian and North American elm taxa that provide a rich genetic pool for future elm breeding programs.
Influence of Irrigation Regime on Water Relations, Gas Exchange, and Growth of Two Field-grown Redbud Varieties in a Semiarid Climate
Authors: Fox Lindsey , Bates Amber , Montague Thayne
Published: August 2020

For three growing seasons (2003–2005) two newly planted, field-grown redbud (Cercis canadensis L.) varieties were subjected to three reference evapotranspiration (ETo)-based irrigation regimes (100, 66, and 33% ETo). Over this time period, water relations (pre-dawn leaf water potential), gas exchange (mid-day stomatal conductance), and growth data (trunk cross sectional area increase, tree leaf area, and shoot elongation) were measured. Pre-dawn leaf water potential (ψl) was more negative for trees receiving the least amount of irrigation, and for Mexican redbud [C. canadensis var. mexicana (Rose) M. Hopkins] trees. However, mid-day stomatal conductance (gs) was similar for Texas redbud (C. canadensis var. texensis S. Watson) trees across the three irrigation regimes, and was highest for Mexican redbud trees receiving the greatest amount of irrigation volume. Growth varied by variety and irrigation regime. Trunk cross sectional area increase was greatest for Mexican redbud trees, leaf area was highest for trees receiving the greatest amount of irrigation, and shoot elongation was greatest for trees receiving the 66% ETo irrigation regime. However, despite differing irrigation volumes, greatest gas exchange and growth was not necessarily associated with greatest irrigation volume. When considering conservation of precious water resources, these redbud varieties maintain adequate growth and appearance under reduced irrigation.
Bleeding Canker of European Beech in Southeastern New York State: Phytophthora Species, Spatial Analysis of Disease, and Periodic Growth of Affected Trees
Authors: Kenaley Shawn C. , Rose Clifford , Sullivan Patrick J. , Hudler George W.
Published: August 2020

The epidemiology of bleeding canker, a Phytophthora-associated disease, on European beech remains unclear. Pathogen surveys as well as dendrological and spatial point pattern analyses (SPPA) were conducted to identify factors contributing to disease progress on beech at the Green-Wood Cemetery (GWC) and Planting Fields Arboretum (PFA) in southeastern New York State. Phytophthora pini was the predominant Phytophthora isolated from cankers as well as soil under asymptomatic and diseased (canker bearing) European beech at each site. No significant differences existed between asymptomatic and Phytophthora-infected trees according to diameter breast height, elevation, and the Phytophthora spp. The radial growth (25-yr chronology for 1986 to 2010) of infected European beech at GWC and PFA, however, was significantly less when compared to asymptomatic beech; yet, residual growth was similar among the latter cohorts, providing no evidence for the instigatory effect(s) of environmental stressors on disease progress. SPPA demonstrated all beech at GWC and PFA were planted in non-random aggregates, whereas the distribution of diseased European beech did not deviate from random. Collectively, results indicated bleeding canker is a slow, chronic disease and the overland tree-to-tree spread of P. pini, and accompanying Phytophthora spp., is rare or does not occur at GWC or PFA.
Composted Cotton Stalks and Cotton Gin Trash Substrate Amendments and Irrigation/Ground Cover Management II. Effect on Growth and Disease Suppression for Azalea and Juniper
Authors: Riley E.D. , Kraus H.T. , Bilderback T.E. , Benson D.M.
Published: August 2020

‘Sunglow’ azalea and ‘Blue Pacific’ juniper were grown in pine bark (PB) and pine tree (PT) substrates that were amended with cotton stalks composted with a N source (CSN), cotton stalks composted without an N source (CS), and cotton gin trash (CGT) to evaluate the substrate's effect on plant growth and disease suppression. The plants were grown under two different, commonly used, irrigation/ground surface management regimes — overhead, sprinkler irrigation with black geotextile weed fabric covering the ground (OH) or low-volume, spray stake irrigation with gravel covering the ground (LV). In 2010, with OH, all PB-amended substrates produced significantly larger azalea shoots than PT-amended substrates. In 2011, with OH, all azalea shoots were similar in size when grown in all substrates except for PT:CS, where plants were significantly smaller. With LV, in 2010 and 2011, azalea shoot growth was largest when grown in a PB substrate amended with CSN or CGT and lowest in PT:CS. Junipers with OH produced generally larger shoot growth with the PB-based substrates in both 2010 and 2011 compared to the PT-based substrates. With LV, PT:CGT produced the numerically smallest juniper shoot growth for both years. Overall, PT-based substrates appeared to produce greater consistency in growth, because responses were more similar in 2010 and 2011, however irrigation method and management can impact growth regardless of substrate composition. CGT added to PB- or PT-based substrates enhanced Ca and Mg uptake by both species but not P uptake. OH generally kept ground surface and substrate temperatures lower than LV regardless of substrate composition. The substrates tested neither enhanced nor deterred P. cinnamomi infection in azalea or juniper.