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F. A. Pokorny and M. E. Austin

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.

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T.E. Bilderback

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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William E. Klingeman*, Darren K. Robinson, and Gary L. McDaniel

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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Jeff L. Sibley, John M. Ruter, and D. Joseph Eakes

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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William F. Hayslett, P. R. Thangudu, and Sabrina Shaw

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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Carole L. Bassett, Robert E. Farrell Jr., and Timothy S. Artlip

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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Amy N. Wright, Alex X. Niemiera, J. Roger Harris, and Robert D. Wright

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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Michael Wisniewski and Les Fuchigami

During autumnal leaf senescence, leaf nitrogen is translocated to bark and root tissues for storage. By definition, proteins that accumulate in large amounts in winter and are absent in summer are called storage proteins. These storage proteins are believed to play an important role in spring growth and helping trees to tolerate and/or recover from both abiotic and biotic stress. Little knowledge exists regarding storage proteins in apple, their physiological function, or how management practices impact them. Our objectives in this research was to characterize seasonally regulated proteins in apple, develop knowledge about their physiological function, and determine how they are affected by management practices. Results of the first-year studies have identified four major proteins that exhibit a seasonal pattern of accumulation in bark tissues of apple. One of these is a pathogenesis-related protein, meaning that it plays a role in disease resistance. Another of these proteins is a stress-related protein important in the use of carbohydrates under stress conditions. A third protein is a vegetative storage protein serving as a reserve for nitrogen. The last protein has not been completely identified. Greatest seasonal fluctuation of these proteins occurred in current season and 1-year-old bark tissues. Experimental studies that achieved varying levels of nitrogen in shoot tissues of young Fuji apple trees were examined for the effect on the accumulation of these proteins. Results indicated that despite a significant increase in total nitrogen, increases in the accumulation of these proteins were only slight. Instead, it appears that most of the nitrogen was present as free amino acids rather than stable proteins. These data indicate that more knowledge is required to determine the benefits and feasibility of elevating the levels of specific proteins in dormant apple trees or trying to manipulate the type of amino acids that accumulate.

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Marilyn B. Odneal and Martin L. Kaps

The recommendation for planting highbush blueberry (Vaccinium corymbosum L.) in Missouri includes the incorporation of sphagnum peat in the planting hole. This experiment compared the use of fresh and aged pine bark to sphagnum peat as soil amendments at planting. One-year-old highbush blueberry `Blueray' plants were planted in 1983 at Mountain Grove, Mo. Plant height, spread, and number of new canes were recorded from 1983 through 1987. Yield and berry size were recorded from 1985 through 1988. There were no significant differences in these measurements among soil amendment treatments (P = 0.05).

Open access

D. A. Eggert and R. A. Hayden

Abstract

Severe symptom of internal bark necrosis (IBN) were noted when trees of ‘Red Delicious’ (‘Bisbee’ strain) on the EM II rootstock were grown hydroponically for 5 months in a complete nutrient regime supplemented with 50 ppm Mn. Lower levels of Mn resulted in less severe symptoms. Experimentally induced lesions were histologically identical to those occurring naturally in the field. Upon histochemical testing, frozen tissue sections obtained from trees grown in excess Mn regimes revealed localized and heavy accumulation of Mn in both incipient and well developed lesions. Localized accumulation of excess Mn may directly cause cell death and lesion formation.