Structure and Seasonal Development of the Secondary Phloem in the Pinaceae

1973 ◽  
Vol 134 (1) ◽  
pp. 17-25 ◽  
Author(s):  
Frank J. Alfieri ◽  
Ray F. Evert
Keyword(s):  
Seasonal Development ◽  
Secondary Phloem

Seasonal Development of the Secondary Phloem in Populus tremuloides

1968 ◽  
Vol 129 (1) ◽  
pp. 1-8 ◽  
Author(s):  
Jerry D. Davis ◽  
Ray F. Evert
Keyword(s):  
Populus Tremuloides ◽  
Seasonal Development ◽  
Secondary Phloem

SEASONAL DEVELOPMENT OF THE SECONDARY PHLOEM IN PINUS

1968 ◽  
Vol 55 (4) ◽  
pp. 518-528 ◽  
Author(s):  
Frank J. Alfieri ◽  
Ray F. Evert
Keyword(s):  
Seasonal Development ◽  
Secondary Phloem

Structure and seasonal development of secondary phloem of Juglans regia

1970 ◽  
Vol 48 (6) ◽  
pp. 1049-1053 ◽  
Author(s):  
Norman W. Schaad ◽  
E. E. Wilson
Keyword(s):  
Juglans Regia ◽  
Growth Increment ◽  
Seasonal Development ◽  
Secondary Phloem ◽  
Early Season ◽  
Central California ◽  
Late Season ◽  
Growth Increments ◽  
Parenchyma Cells ◽  
Sieve Tubes

In Persian walnut (Juglans regia L.), as in other deciduous dicotyledonous trees, a small (0.5 mm) amount of secondary phloem is functional for only one season and a large amount is nonfunctional. In 1968 in Central California the cycle of phloem development began in late February and ended sometime before mid-October. The phloem annual ring was composed of distinctive tangential bands, allowing easy distinction of seasonal growth increments. Each growth increment could be divided into early- and late-season tissue. Early-season phloem, composed principally of large sieve tubes, was separated from late-season phloem by a band of fibers. The late-season phloem was composed of a mixture of narrow sieve tubes, parenchyma cells, and, occasionally, an incomplete tangential band of fibers. The annual rings were not crushed except for the early-season phloem, which was somewhat compressed by growth of the woody cylinder. The bark of walnut becomes thicker with age because of this and the enlargement of parenchyma cells.

Wood and Bark Anatomy of Lauraceae. ii. Licaria Aublet

IAWA Journal ◽  
1985 ◽  
Vol 6 (3) ◽  
pp. 187-199 ◽  
Author(s):  
Hans Georg Richter
Keyword(s):  
Diagnostic Tool ◽  
Secondary Xylem ◽  
Secondary Phloem ◽  
Structural Profile ◽  
Quantitative Characters ◽  
Important Diagnostic Tool ◽  
Species Groups ◽  
Bark Anatomy

Qualitative features of the secondary xylem of Licaria present a rather uniform structural profile. Constant differences in primarily quantitative characters lead to the formation of speeies groups wh ich loosely correspond to infrageneric sections based on floral and vegetative morphology. This subdivision is strongly corroborated by the highly variable secondary phloem structurc revealing considerable diversity in type and distribution of sc1erenchymatic tissues. Inorganic inclusions in the secondary xylem, crystals and silica, constitute an important diagnostic tool for differentiating certain species and species groups, but are hardly of importance in the bark.

Seasonal Variation in Traumatic Resin Canal Formation in Chamaecyparis Obtusa Phloem

IAWA Journal ◽  
1998 ◽  
Vol 19 (2) ◽  
pp. 181-189 ◽  
Author(s):  
Keiko Kuroda
Keyword(s):  
Annual Ring ◽  
Stem Canker ◽  
Chamaecyparis Obtusa ◽  
Resin Canal ◽  
Annual Rings ◽  
Secondary Phloem ◽  
Resinous Stem Canker ◽  
Traumatic Resin Canals ◽  
Resin Canals ◽  
Artificial Wounding

Trunks of Chamaecyparis obtusa were injured to examine seasonal differences in traumatic resin canal formation in secondary phloem. Even after wounding during winter, differentiation of axial parenchyma into epithelium was initiated, and vertical resin canals formed. After winter wounding, resin canal development was slower and the tangential extent of resin canals was narrower than after spring wounding, and it took one to two months until resin secretion began. After spring wounding, the sites of resin canal formation were the 1- and 2-year-old annual rings of phloem. In August, the location of resin canal formation shifted into the current and 1-year-old annual ring. Resin canals never formed in secondary phloem areas that were 3 or more years old. In C. obtusa trunks that are affected by the resinous stem canker, numerous tangentiallines of resin canals are found throughout the phloem, not just recent and 1- to 2-year-old phloem. The present research indicates that these many lines of resin canals were not formed at one time, and that the stimuli that induce traumatic resin canals must occur repeatedly over many years. The data on artificial wounding effects are useful for understanding resinous stem canker.

scholarly journals The Epidemiology of Powdery Mildew on Concord Grapes

2001 ◽  
Vol 91 (10) ◽  
pp. 948-955 ◽  
Author(s):  
David M. Gadoury ◽  
Robert C. Seem ◽  
Andrea Ficke ◽  
Wayne F. Wilcox
Keyword(s):  
Powdery Mildew ◽  
Fruit Set ◽  
Disease Incidence ◽  
The United States ◽  
Seasonal Development ◽  
Peak Period ◽  
Late Season ◽  
Stage Of Development ◽  
Concord Grapes ◽  
Moderately Resistant

Vitis labruscana ‘Concord’ is a grape cultivar widely grown in the United States for processing into juice and other grape products. Concord grapes are sporadically but sometimes severely damaged by the grape powdery mildew pathogen, Uncinula necator. Although the foliage is often reported to be moderately resistant to powdery mildew, severe fruit infection occurs in some years. We observed the seasonal development of powdery mildew on leaves, rachises, and berries of unsprayed Concord grapevines. Inoculations of flower and fruit clusters revealed a brief period of berry susceptibility and a protracted period of rachis susceptibility. The rachis remained highly susceptible to infection, and the severity of rachis infection increased throughout the growing season until the rachis formed a periderm shortly before harvest. In contrast, berries were nearly immune to infection within 2 weeks after fruit set. Rachis and berry infections were detected before the disease was observed on foliage, and the incidence of rachis and berry infection often exceeded disease incidence observed on foliage until after fruit acquired substantial ontogenic resistance. Excellent control of fruit infection, and adequate control of leaf infection, was achieved by two fungicide applications targeted at the peak period of fruit susceptibility. Although Concord is thought to be moderately resistant to powdery mildew, the rachis is highly susceptible, and may be the avenue by which prebloom infections make their way onto the developing fruit. Late-season infection of the rachis neither spread to the fruit, nor did it cause fruit to drop prematurely, and may be of little economic consequence on fruit destined for processing. Although fruit of V. vinifera cultivars have been reported to remain susceptible to infection until berry sugar levels reach 8 to 15%, Concord fruit become nearly immune to infection nearly 6 weeks before this stage of development. Because powdery mildew does not become conspicuous on foliage until late summer, it is generally regarded as a late-season problem on Concord grapes, and previous management programs have reflected this belief. However, the greatest contribution to control of fruit infection is due to fungicides applied during the peak period of fruit susceptibility, from bloom until shortly after fruit set, long before the disease is observed on foliage.

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