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- Author or Editor: C. H. Gilliam x
The effects of 3 nitrogen treatments on tissue N fluctuations of ‘Helleri’ holly. All N concentrations increased following the cessation of shoot elongation until a concentration of tissue N was reached where a new flush of growth began. Nitrogen concentrations at which new growth began were about the same for all N treatments. The time necessary to reach this concentration was dependent on the level of N added; 5 weeks for 300 ppm, 13 weeks for 150 ppm and 18 weeks for 50 ppm N. Once new growth began, tissue N concentrations began to decrease.
Fertilizer applied during a period following the cessation of stem elongation and before the next flush resulted in greater total tissue N and shoot growth than applications made during other stages of growth in ‘Helleri’ holly. Root growth was suppressed by 3 or more fertilizer applications, regardless of the time of application.
The effects of 3 nitrogen levels and 2 growth regulators on growth of winter- and summer-rooted cuttings of Ilex crenata cv. Helleri were studied. Nitrogen applications promoted bud break immediately after rooting on summer cuttings and also enhanced the growth of winter-rooted cuttings. Generally, plants grown at 300 or 150 ppm N had greater shoot numbers and length, height, width, and dry weight compared to plants grown at 50 ppm N. Also spring growth of these liners was markedly enhanced by the higher level of N applied the previous season. Benzyladenine (BA) at 600 ppm increased the number of breaks and suppressed stem length, while gibberellic acid (GA3) at 400 ppm decreased the number of breaks and increased stem length.
High correlation coefficients were found between plant growth (dry weight accumulation) and both leaf N content and soil solution nitrates, while low correlation coefficients were found between soil nitrates and plant growth of 3 holly cultivars, Ilex crenata Thunb. cvs. Helleri and Rotundifolia and Ilex cornuta Lindl. et Paxt. cv. Burfordi, grown in 3 liter container at 200, 300, 400 and 500 ppm nitrogen. Shoot growth of ‘Helleri’ and ‘Burfordi’ was not increased by N levels higher than 300 ppm, while 400 ppm was optimal for ‘Rotundifolia.’
Two studies were conducted to evaluate recycled newspaper mulch for landscape plantings. In the first study, two paper products (pellets and crumble) were tested at three depths. Application of either 25 or 50 mm provided excellent control of prostrate spurge. Of the four annuals grown, ageratum exhibited severe stunting of roots and shoots. In the second study, three annual species were mulched with the two recycled paper products applied at 25 mm each and adjusted with P at 0, 3.75, or 7.5 ppm to bind excess Al. When no P was added, ageratum growth was about half that of the control plants. Addition of P at either rate resulted in similar growth compared to control plants. Marigold and geranium were less affected by recycled paper mulch; however, when P was added growth was always similar to nonmulched control plants.
Improved water use efficiency exists for plants grown in modified containers to minimize leaching and reduce irrigation frequency which subsequently reduces NO3-N leachate. Salvia splendens `Bonfire' and Impatiens wallerana `Pink' (super elfin hybrid) were potted in ProMix BX medium (Premier Brands, Inc., Stamford, CT) into nine container styles with modified drainage holes to determine leachate volume and quantify NO3-N leached. Three styles had four drainage holes on the container side with hole diameters of 0.5, 1.0, and 1.9 cm, respectively; three styles had four drainage holes on the container side and one drainage hole in the bottom center with hole diameters of 0.5, 1.0, and 1.9 cm, respectively; and three styles had one drainage hole in the bottom center with hole diameters of 0.5, 1.6, and 1.9 cm, respectively. Plants were hand watered when an individual container's medium reached 80% of container capacity. Leachate volume, irrigation frequency, and leachate NO3-N was reduced as drainage size hole decreased in size and number. Plant quality was similar among container modifications.
Phytotoxicity associated with application of 0.28 kg·ha−1 a.i. of the 4E formulation of fluazifop-butyl to Rhododendron ‘Hino-crimson’ was characterized by plant response similar to the response to chemical pinching. Flowering the following spring increased with fluazifop-butyl treatment. In a separate study, application of 1E PP005 (a formulation containing only the active isomer fluazifop-butyl) produced effects similar to the 4E formulation at one-half the rate (0.14 kg·ha−1). Chemical name used: butyl (±)-2-[4-[[5-(trifluoromethyl)-2-pyridinyl]oxy]phenoxy]propanoic acid (fluazifop-butyl).
Little information is available on herbicide movement in soilless container media and subsequent movement in container leachate and container bed runoff. The objective of this study was to evaluate oxyfluorfen movement in irrigation water following application to container grown nursery crops in a commercial nursery. Oxyfluorfen levels in the container bed runoff were 9 to 27 times higher than those in container leachate during the 3 irrigations following herbicide application. Maximum oxyfluorfen level in the container leachate was 8.3 ppb following the first irrigation but declined to 2.0 ppb by the 12th irrigation. The oxyfluorfen level was still about 2.0 ppb following the 75th irrigation. Oxyfluorfen in the container bed runoff peaked at 99 ppb following the 3rd irrigation before declining to 67 ppb following the 6th irrigation.
Taxus media Rehd. ‘Anderson’ were grown at 4 boron rates: 0.5, 5.0, 25.0 and 50.0 ppm using 2 media:4 pinebark:l sand and 4 hardwood bark:l sand. toxicity symptoms developed when foliar concentration was between 85–100 μg/g of dry tissue. Foliar symptoms of toxicity were characterized by leaf-tip yellowing followed by leaf-tip necrosis and premature defoliation. Shoot and root growth were suppressed at the 50 ppm application rate. continued to accumulate in the foliage after the 2 higher rates of were discontinued. Foliar concentration of Ca, Mn, Fe and Zn were lower when plants were grown with 25 and 50 ppm when compared to plants grown with 0.5 and 5 ppm B.
Obtaining quality photos of plant material to demonstrate research results is sometimes difficult. Adequate sunlight is necessary for photographing plants outdoors or in the greenhouse and shading may cause unsatisfactory results (Fig. 1). An alternative to using natural light is a system of 4 or 5 photoflood lights to illuminate subject from different angles. Although effective, this method requires a sizeable investment and is not very portable.