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Abstract

‘Red Prince Delicious’ apples/‘M7’ rootstocks, growing in sand culture and receiving ½, 5 or 50 ppm Mn, developed internal bark necrosis (IBN), and an Fe-deficiency chlorosis in its severest expression, at the highest level of Mn supply. Fe was as high in leaves of chlorotic as in those of non-chlorotic plants, but the chlorosis was cleared up by increasing the Fe supply.

Ground twigs showed a brownish coloration which had a max reflectance at 700 mμ. Differences in coloration were correlated with the Mn supply, the severity of IBN symptoms and the Mn/Fe ratio in the leaves and bark, but not with the Mn/Fe ratio in the ground twigs.

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Abstract

Nitrapyrin at 50 ppm, increased dry weights of tomato (Lycopersicon esculentum Mill.) and total N when pine bark comprised part of the medium and NH4 was part of the N treatment. If the medium consisted only of pine bark, nitrapyrin increased dry weights and total plant N with NO3–N and/or NH4–N treatments. The NO3–N level in the medium was higher with all N treatments when nitrapyrin was incorporated. The increase in plant growth is directly related to the higher NO3–N levels in each medium where nitrapyrin was incorporated. The higher media NO3–N with nitrapyrin are attributed to inhibition of the nitrification process and a subsequent inhibitory effect on NO3–N loss.

Open Access

Abstract

Softwood terminal cuttings of ‘Woodard’ and ‘Tifblue’ blueberry (Vaccinium ashei Reade) rooted best in media containing milled pine bark alone or mixed with equal parts of perlite, compared to sphagnum peatmoss alone or mixed with equal parts of perlite. Percentage rooting, root quality, and percentage marketability of softwood terminal cuttings of Vaccinium ‘Tifton 275’, a complex hybrid of V. corymbosum L. and V. ashei, was unaffected by rooting medium.

Open Access
Authors: and

The genus Ulmus contains numerous stress-tolerant species, especially those from areas of China with climates similar to various regions of the United States. Lace-bark elm, Ulmus parvifolia, the true Chinese elm, has an extensive temperature distribution range in China and offers great promise as a street tree. The high resistance of this elm to Dutch elm disease and other elm problems makes it an excellent tree for urban landscapes. Two new U. parvifolia cultivars, Athena® and Allee®, are not cold hardy for northern climates and there is a need for new cold hardy lace-bark elms. Screening thousands of seedlings for cold hardiness, upright form, beautiful bark characteristics, and larger leaves will bring the most desirable U. parvifolia cultivars into the green industry. We determined that seed dormancy and the percentage of seed germination of four selected lacebark elms after 2 and 4 weeks were >30% and >50%, respectively. There were significant differences in stem cold hardiness among new lace-bark elms from China (about –32 to –40 °C). Laboratory determination of cold hardiness can provide great advantages over years of field testing. Response to the outdoor temperature in December, January, and February on a seed cold hardiness freezing test showed significant reduction in seed germination, especially at –30 °C. Freezing test of seeds to –40 °C, resulted in lt 50 of –3 to –5 °C in December, so, it is less likely that these U. parvifoilia will become invasive in northern latitudes. Invasiveness of these U. parvifolia for higher zones, e.g., 6–8 could be greater and selection of these elms is suitable for zones 5 and lower. Planting these elms in zones 4, 3, and 2 will give us useful information regarding their winter performance.

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The objective of this study was to determine the effects of lime and micronutrient amendments on growth of seedlings of nine container-grown landscape tree species in two pine bark substrates with different pHs. Acer palmatum Thunb. (Japanese maple), Acer saccharum Marsh. (sugar maple), Cercis canadensis L. (redbud), Cornus florida L. (flowering dogwood), Cornus kousa Hance. (kousa dogwood), Koelreuteria paniculata Laxm. (golden-rain tree), Magnolia ×soulangiana Soul.-Bod. `Lennei' (magnolia), Nyssa sylvatica Marsh. (blackgum), and Quercus palustris Müenchh. (pin oak) were grown from seed in two pine bark substrates with different pHs (pH 4.7 and 5.1) (Expt. 1). Preplant amendment treatments for each of two pine (Pinus taeda L.) bark sources were: with and without dolomitic limestone (3.6 kg·m–3) and with and without micronutrients (0.9 kg·m–3), and with and without micronutrients (0.9 kg·m–3), supplied as Micromax. Seedlings were harvested 12 and 19 weeks after seeds were planted, and shoot dry weight and tree height were determined. The same experiment was repeated using two of the nine species from Expt. 1 and pine bark substrates at pH 5.1 and 5.8 (Expt. 2). Seedling shoot dry weight and height were measured 11 weeks after planting. For both experiments, pine bark solutions were extracted using the pour-through method and analyzed for Ca, Mg, Fe, Mn, Cu, and Zn. Growth of all species in both experiments was greater in micronutrient-amended than in lime-amended bark. In general, adding micronutrients increased nutrient concentrations in the pine bark solution, while adding lime decreased them. Effect of bark type on growth in Expt. 1 was variable; however, in Expt. 2, growth was greater in the low pH bark than in the high pH bark. In general, nutrient concentrations in bark solutions were higher in low pH bark than in high pH bark for both experiments. Under the pH conditions of this experiment, micronutrient additions stimulated growth whereas a lime amendment did not.

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The objective of this study was to determine differences in the bulk anthocyanin content of bark tissue of container-grown red maple (Acer rubrum L. and Acer ×freemanii E. Murray) at two Georgia locations with different environmental conditions. Rooted cuttings and tissue-cultured plantlets of eight cultivars were grown in either Blairsville or Tifton, Ga. [U.S. Dept. of Agriculture (USDA) Hardiness Zones 6b and 8a; American Horticultural Society (AHS) Heat Zones 5 and 8, respectively], from June 1995 until Dec. 1996. Bark tissue from twigs of trees grown in Blairsville was visually redder and contained more total anthocyanin than did that of trees grown in Tifton. Levels of total anthocyanins were higher (P = 0.0007) at Blairsville (0.087 mg·g-1, N = 48) than at Tifton (0.068 mg·g-1, N = 47). At both locations the levels were highest in `Landsburg' (`Firedance'™), followed by `Franksred' (`Red Sunset'™) and `October Glory'. This is the first report to quantify anthocyanin differences in bark tissue of container-grown trees. Cooler nights in Blairsville might have contributed to increased coloration by reducing respiratory losses, thus leaving more carbohydrates available for pigment production.

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Genes whose expression is regulated by exposure to low temperature (LT) in peach (Prunus persica L. Batsch.) bark were identified by PCR suppression subtractive hybridization. Among the genes identified by this technique were several that had previously been associated with LT responsiveness, as well as a few that have not been reported to be regulated by cold. Genes represented by the first group included Ppdhn1, previously characterized as a seasonally expressed gene predominantly seen in bark tissue collected in winter months. A novel dehydrin found in this study, Ppdhn3, was also observed to be up-regulated at LT and seasonally expressed. Two genes not previously associated with LT response were found to be up-regulated at 5 °C. These genes encode a polypeptide related to some unknown mitochondrial process (Pptar1p) or a transducin-like protein (Pptlp1) that may be associated with signal transduction. Expression of these genes with respect to seasonal variation and drought stress is compared to genes from peach bark (Ppdhn1 and Ppdhn2), whose patterns of expression in different seasons and under water deficit are well documented.

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Ilex × `Nellie R. Stevens' holly, Rhododendron sp. `Hinodegeri' azalea and Pyracantha coccinea, scarlet firethorn rooted cuttings were potted in • 3.81 containers. Irrigation was applied by Dram rings daily, or every 2,4,or 6 days. Approximately 1000 ml of water were applied at each irrigation. Three container media, including pine bark, and pine bark amended with either Terra-Sorb AG synthetic moisture extender incorporated at 1.2 kg/m3 or Aqua-Gro G wetting agent incorporated at 0.9 kg/m3 plus monthly drenches of 700 ml of 2500 ppm Aqua-Gro L were compared for physical and chemical properties and plant growth responses. Decreasing irrigation decreased pH, increased nutrient leachate levels, and increased foliar tissue levels of N,P,K,Ca,and Fe in holly and azalea. Pyracantha top and root dry weight was reduced at 4 and 6 day irrigation intervals, holly top growth was reduced by 6 day and azalea had greatest shoot growth at 2 day irrigation and was reduced by other irrigation frequencies. Top growth of all 3 species and root growth of pyracantha was reduced in the pine bark treatment.

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A field study was conducted at Tennessee State University's research station to evaluate the effect of hardwood bark mulch on the winter survival of garden mums. A randomized complete block design was used. Cultivars used were adorn, encore, grandchild, jackpot, legend, minnautumn, minnwhite and triump. At the end of the flowering season the tops were removed leaving a four inch stubble in the mulch. The number of mum plants that resumed growth the following spring were counted for each cultivar. There was a difference in the winter survival of the different cultivars as well as a significant difference in the mulch treated and the control. Grandchild and jackpot were most cold hardy followed by encore, minnwhite, minnautumn, triump, legend, and adorn. Grandchild and jackpot with four inches of hardwood bark mulch had an 88 percent survival while the control had a 44 percent survival. Adorn. had a 51 percent survival with four inches of mulch and a 20 percent survival in the control. This data shows that hardwood bark mulch holds a great potential for providing excellent winter protection for garden mums.

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Mugwort, or false chrysanthemum (Artemisia vulgaris L) is a well-adapted invasive plant that presents increasing management challenges to agricultural producers, Green Industry professionals and homeowners across portions of the eastern U.S. The ability of mugwort to regenerate from cut rhizome sections has not been adequately quantified for substrates that are typical of landscapes and nursery fields, container nurseries, and propagation beds. Cut rhizome sections were analyzed by rhizome color, length, and the presence or absence of a leaf scale. Media substrates included pine bark, sand, and soil. Rhizomes darken with time and color did not account for differences in growth among treatments. When grown in pine bark, sand, and soil substrates during 45-d trials, 85%, 78%, and 69% of 2 cm-long rhizome sections produced both roots and shoots. These results contrast with previous research. When rhizome fragments 0.5 cm long did not include a leaf scale, slightly fewer than 31% produced both roots and shoots in soil. Fewer rhizomes survived in soil, but root and shoot fresh masses of soil-grown rhizomes were greater than rhizomes that were regenerated in pine bark and sand. When rhizome sections had a leaf scale, survival, fresh masses of roots and shoots, shoot height, leaf number and root lengths were greater, regardless of substrate type. Root initials emerged in the internode between leaf scales and also adjacent to leaf scales. Shoot emergence preceded root emergence from rhizome sections. Growers, landscape managers and homeowners should scout regularly and initiate aggressive controls when mugwort populations are found.

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