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Phenology and fungus‐nematode relations of corky root disease of Douglas‐fir
Author(s) -
BLOOMBERG W. J.,
SUTHERLAND JACK R.
Publication year - 1971
Publication title -
annals of applied biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.677
H-Index - 80
eISSN - 1744-7348
pISSN - 0003-4746
DOI - 10.1111/j.1744-7348.1971.tb04679.x
Subject(s) - biology , germination , botany , fungus , endodermis , mycelium , fusarium oxysporum , nematode , pericycle , phenology , nematology , horticulture , ecology , biochemistry , arabidopsis , gene , mutant
SUMMARY Symptoms of corky root disease of Douglas‐fir seedlings include: (I) swollen tap‐ and lateral roots; (2) paucity of lateral roots; and (3) stunted shoot growth. In diseased roots, the primary cortex persisted and enlarged, but secondary vascular tissues, periderm, pericycle and endodermis were reduced. Cylindrocarpon destructans was the fungus most frequently isolated from cortical cells and symptoms were induced by massive inoculum of some isolates but not by dispersed inoculum nor by extracts from cultures. Whereas symptoms first appeared 2 months after seeds sown in May germinated, C. destructans was rarely isolated until 4 months after germination. Relatively more colonies of C. destructans were isolated from corky roots in the winter than in the summer, when Fusarium oxysporum or Mycelium radicis atrovirens were more abundant. Populations of the plant‐parasitic nematode Xiphinema bakeri on roots and in adhering soil were highest 2 months after germination and during the summer, correlating positively with the per cent of tap‐root affected and negatively with numbers of lateral roots.