Abstract
Quantitative assessments of the degree of susceptibility to experimental infection by Erwinia rubrifaciens Wilson et al. were made on 54 cultivars of Juglans regia L., J. hindsii Jepson, and J. nigra L. on J. hindsii and Paradox rootstocks. Forty-five of the 54 cultivars were susceptible and developed symptoms characteristic of deep bark canker. On Paradox rootstock, ‘Pioneer,’ ‘Early Erhardt,’ ‘Willson-Franquette,’ ‘Sinensisy5,’ ‘Conway-Mayette,’ ‘Scharsch-Franquette,’ ‘Meylan,’ and ‘Sinensis-7’ showed canker extension rates greater than ‘Hartley’; whereas, on J. hindsii rootstock only ‘Sinensis-5’ and ‘Sinensis-7’ showed canker extension rates greater than ‘Hartley.’ All cultivars were ranked into 4 susceptibility groups according to their rates of canker extension: group I (0 mm/day), group II (0.01 to 0.10 mm/day), group III (0.101 to 0.200 mm/day) and group IV (0.201 to 1.0 or greater mm/day). Of 54 cultivars only 8 ranked in group I (non-susceptible); 28 ranked in group II (dry-canker types); 11 ranked in group III (moderately susceptible); and 7 ranked in group IV (highly susceptible). ‘Hartley,’ the only cultivar commonly associated with the disease in commercial plantings ranked in group IV. Cultivars of either J. hindsii or J. nigra were ranked in group I. Erwinia rubrifaciens was recovered from 45 of 54 cultivars, 14 months after experimental inoculation and 23 of 54 cultivars after 26 months. The pathogenic bacterium was recovered from cultivars of group I (that displayed no visible symptoms). It is hypothesized that natural populations of J. hindsii and J. nigra may harbor E. rubrifaciens and may have been the original inoculum source.
Abstract
Pine bark cation exchange capacity (CEC) (by Ba/Mg exchange on four particle size fractions) increased regularly from 38 to 98 meq/100 g between pH 4 and 7. Decreasing particle size from <2.38 to <0.05 mm did not result in the expected large increases in bark CEC. The Ba/Mg CEC of unsieved bark samples was less than that determined by the weighted average of component size fractions. Monovalent/monovalent-determined CEC was higher than Ba/Mg, indicating that a number of differing charge-specific sites are involved. The pH-dependent CEC increase between pH 4 and 7 was greater for divalent exchange than for monovalent. Ammonium/K CEC was higher than K/NH4 CEC, probably due to enhanced NH4 adsorption by carboxyl groups. Infrared analysis of pine bark revealed that surface functional group composition is similar to soil organic matter. The accurate measurement of CEC in pine bark is complicated by solution pH and ionic strength, as well as by the cations employed for exchange.
Abstract
Three genera of woody plants were container-grown in a pine bark medium. Pine bark was amended or unamended with nitrapyrin (NI) and fertilized with an NH4-N fertilizer. Medium solution NH4-N concentrations of bark without NI decreased rapidly for the first 3 to 5 weeks with a concomitant increase in NO3-N concentrations. Medium solution pH at 0 NI decreased 0.8 unit during periods of rapid NO3-N accumulation. The low medium solution pH of the 0 NI treatment resulted in solution Ca, Mg, and Mn concentrations that were several times greater than at 82 μg of NI. Correspondingly, tissue concentrations of these ions were generally greater at the 0 NI treatment than at the 82 μg NI treatment. In general, there were no differences in shoot dry weight in response to NI treatment. Results indicate that nitrification is important in the nutrition of container-grown plants.
Taxonomy, Phylogeny, and Ecology of Bark-inhabiting and Tree-pathogenic Fungi in the Cryphonectriaceae. M. Gryzenhout, B.D. Wingfield, and M.J. Wingfield. 2009. APS Press, St. Paul, MN 55121. 136 pages, 14 color images, 38 black and white images
Abstract
Plant dry weight of tomato (Lycopersicon esculentum Mill.) grown in aged bark media was equal to or greater than that of those cultured in a control medium of perlite-sand. Plant growth in fresh bark was inhibited initially and then recovered. Zn concentration and total content per plant were high for plants cultured in bark media even when little or no Zn was applied. The intereaction between media and applied Zn was significant. Plant Zn increased with increasing amount of applied soluble Zn when cultured in perlite-sand, but did not normally change for plants cultured in bark. High Zn concentration of plants cultured in fresh bark was too low to account for the initial growth inhibition. N concentration and content per plant were normally lower for plants grown in fresh bark. N of plants in aged bark was similar to plants in the standard medium. Growth inhibition of plants in fresh bark did not appear to be due to N deficiency.
Abstract
Chrysanthemum morifolium Ramat. cv. Sunny Mandalay plants were grown in hardwood bark media amended with various levels of insoluble poly (ethylene oxide) (Viterra Hydrogel, VH). Plants grown in rates ranging from 57–454 g/0.03 m3 required less watering, had increased shelf life, and exhibited no phytotoxicity.
Abstract
Manganese toxicity was expressed as leaf chlorosis, early leaf abscission, reduced flower bud number, reduced growth, and internal bark necrosis (IBN). Increasing Ca or decreasing Mn in the solution were effective in correcting IBN, while increasing B or pH were ineffective. High solution Mn was associated with a decrease in bark Ca, and high solution Ca was associated with decreased Mn accumulation. Severe IBN was observed on the ‘Delicious’ scion, but no bark symptoms were visible on the EM IX clonal stock. Manganese concn were similar in both stock and scion bark, but Ca levels in the stock bark were substantially higher than those in the scion.
Abstract
An amended pine bark growing medium was extracted for varying lengths of time using modified Spurway, Louisiana State Univ. (LSU), and double acid analytical systems. Concentrations of P, K, Ca, and Mg were then determined in the filtrate. As the extraction time was lengthened, the quantity of P, K, Ca, and Mg removed from the medium increased for each system. The concentration and type of nutrients removed varied according to the composition and action of the extractant.
Seasonal pattern of cold tolerance and proteins were studied in the leaves of sibling deciduous and evergreen peach (Prunus persica). In contrast to deciduous peach that undergoes endodormancy in fall, evergreen peach does not (leaves are retained and shoot tips elongate under favorable conditions) (Arora et al., Plant Physiol. 99:1562-1568). Cold tolerance (LT50) was assessed using electrolyte leakage method. Proteins were separated by SDS-PAGE. Electroblots were probed with anti-dehydrin (Dr. T. Close) and anti-19 kD, peach bark storage protein (BSP) antibodies. LT50 of leaves successively increased from about -7C (18 Aug.) to -15C and -11.5C (23 Oct.) in deciduous and evergreen genotypes, respectively. The most apparent change in the protein profiles was the accumulation of a 60-kD protein during cold acclimation in the leaves of deciduous trees; however, it did not change significantly in evergreen peach. Immunoblots indicate that 60-kD protein is a dehydrin protein. PAGE and immunoblots indicated that 19-kD BSP disappeared progressively during summer through fall in the leaves of deciduous peach, but accumulated to large amounts in bark tissues. Similar inverse relationship for its accumulation in leaf vs. bark tissue was not evident in evergreen peach. Results indicate that BSP expression may be regulated by altered source/sink relationship.
An experiment with a factorial treatment combination in a split plot design with five single plant replications was conducted to evaluate the effects of five rates of fertilizer addition and two irrigation volumes on plant growth in a composted turkey-litter-amended pine bark substrate. Main plots were daily applications of 600 or 900 ml/3.8-L container. Subplots were either 0, 1.0, 2.0, 3.0, or 4.0 g N additions (Osmocote High H 24N–1.7P–5.8K) per container topdressed on a substrate composed of pine bark amended with 8% (by volume) composted turkey litter. No additional amendments were made to the compost amended substrates. An additional “industry control” treatment consisted of an 8 pine bark: 1 sand (by volume) substrate amended with 3.0 kg/m3 dolomitic limestone and 0.9 kg/m3 Micromax and topdressed with 3.5 g N (Osmocote High N) per container. After 134 days, Cotoneaster dammeri `Skogholm' and Rudbeckia fulgida `Goldsturm' plants were harvested and shoot and root (cotoneaster only) dry weights were determined. Cotoneaster shoot and root dry weights and rudbeckia shoot dry weight increased linearly as N rate increased from 0 to 4.0 g N. Irrigation volume did not affect cotoneaster shoot or root dry weights. Rudbeckia shoot dry weight was 18% greater with 900 ml than with 600 ml of irrigation. Rudbeckia growth in compost amended substrate was greater than in the industry control when topdressed with ≥1.0 g N. Shoot growth of cotoneaster in the industry control substrate and compost amended substrate with ≥ 3.0 g N applied was similar.