In:
Australian Journal of Botany, CSIRO Publishing, Vol. 31, No. 2 ( 1983), p. 197-
Abstract:
Phytophthora cinnamomi Rands invaded the secondary phloem of inoculated roots and stems of
Eucalyptus marginata Donn. ex Sm. For 12 months after inoculation, lesion development was followed in coppice stems. As lesions extended, the phloem or inner bark became discoloured due to the
accumulation and oxidation of polyphenols. Starch also was deposited in the necrotic phloem. The primary wall material of sieve tubes and associated parenchyma was hydrolysed but fibres were
unaffected. Fungal spread was most rapid in the outer phloem tissue where cells were loosely packed and characterized by many expanded parenchyma cells. Fungal invasion of the inner phloem resulted
in cambial kill. Roots were not girdled by the fungus in the first 12 months after inoculation, as they resisted tangential spread of the fungus more effectively than coppice stems. Lesions were contained
once necrophylactic (wound) periderms formed in the bark. Although the necrophylactic periderm restricted fungal activity during winter and spring, the fungus did 'break-out' in summer and invade
new areas of phloem in 50% of the inoculated roots and stems. Summer lesion extension was usually associated with kino production: a series of kino veins reflected the intermittent activity of the fungus.
Once the characteristics of typical lesions were recognized, interpretation of root lesions resulting from natural infections was possible.
Type of Medium:
Online Resource
ISSN:
0067-1924
Language:
English
Publisher:
CSIRO Publishing
Publication Date:
1983
detail.hit.zdb_id:
1496155-6
SSG:
12
