University of California

Condition of phloem of sour orange tree trunk in winter


Henry Schneider

Author Affiliations

Henry Schneider was Associate Plant Pathologist in the Experiment Station, Riverside.

Publication Information

Hilgardia 22(16):583-591. DOI:10.3733/hilg.v22n16p583. February 1954.

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Since the sieve tubes of the functioning phloem of sour orange stock of sweet orange trees become necrotic when the tree is affected by quick decline, the condition of the functioning phloem of the trunk of the healthy sour orange, both as a rootstock and as a seedling tree, especially in winter, was investigated.

Throughout the winter months trunks of healthy sour orange trees, and of sour orange rootstock under sweet orange tops, maintained a band of functioning phloem averaging about 500 microns in width. A ring of degenerating phloem external to this was either absent or as much as 100 microns wide. Occasionally, there were abnormally wide bands of degenerating phloem or bands of necrotic sieve tubes within the functioning phloem.

Literature Cited

Esau Katherine. Development and structure of the phloem tissue. II. Bot. Rev. 1950. 16:67-114.

Schneider Henry. The phloem of the sweet orange tree trunk and the seasonal production of xylem and phloem. Hilgardia. 1952. 21:331-6. DOI: 10.3733/hilg.v21n12p331 [CrossRef]

Schneider Henry. Anatomy of bark of bud union, trunk, and roots of quick-decline-affected sweet orange trees on sour orange rootstock. Hilgardia. 1954. 22(16):567-81. DOI: 10.3733/hilg.v22n16p567 [CrossRef]

Webber Herbert John, Dexter Batchelor Leon. The citrus industry, Vol. I. History, botany, and breeding. 1946. Berkeley and Los Angeles: University of California Press. xx + 1028p.

Schneider H. 1954. Condition of phloem of sour orange tree trunk in winter. Hilgardia 22(16):583-591. DOI:10.3733/hilg.v22n16p583
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