Acronecrosis, or top-necrosis, is a systemic virus disease which manifests itself in certain potato varieties following graft introduction of certain specific plant viruses. Acronecrosis is externally characterized by a necrotic spotting of the uppermost leaves followed by a dying of the plant from the top, downward, in the absence of any mottling. Necrotic areas are invariably found in the stem. These necroses, which are most severe in the distal portions of the plant, originate usually but not always, In the internal phloem and spread into the surrounding tissues. Necroses, similar in their origin and appearance to those in the stem, are found in the petioles, frequently being so severe as to lead to the death of the leaf blades. Axillary buds also become infected and are ultimately killed. In the tubers the necroses develop in the same manner as those in the stem, and spread rapidly to the storage parenchyma. Cork layers abstricting the necrotic areas are always found in affected tubers and are produced occasionally in stems grown at high temperatures. Usually the tuber necrosis spreads by way of the vascular tissues to one or more of the eyes and kills the buds, causing an irregular, sunken depression on the surface of the tuber. Often, buds of some eyes survive to produce secondary plants which soon develop necrotic spots similar to those in the parent plant. [...]
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.122917 |
| Date | January 1949 |
| Creators | Bagnall, Richard Herbert. |
| Contributors | Coulson, J. (Supervisor) |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Master of Science. (Department of Plant Pathology.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 000591220, Theses scanned by McGill Library. |
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