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The colonisation of fallen apple leaves by Phytophthora syringae in relation to inoculum levels in orchard soil
Author(s) -
HARRIS D. C.
Publication year - 1985
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.1744-7348.1985.tb01561.x
Subject(s) - biology , zoospore , oospore , inoculation , sporangium , pseudomonas syringae , orchard , botany , phytophthora , colonisation , rosaceae , desiccation , horticulture , spore , phytophthora cactorum , phycomycetes , colonization , microbiology and biotechnology , pathogen
SUMMARY Freshly abscissed apple leaves were rapidly infected after inoculation with zoospores of Phytophthora syringae . Mesophyll was extensively colonised within 4 days, sporangia and sex organs were formed within 9 days, but oospore maturation took several weeks. Oospores developed abundantly in leaves of all nine apple cvs tested. The ability of P. syringae to colonise leaf tissue diminished rapidly as leaves senesced, was prevented if leaves were first killed by freezing or desiccation, but was unaffected by watersoaking leaves before inoculation. Of nine soil samples from five apple orchards analysed for P. syringae by dilution and baiting, seven contained from 7–16 infective units/g, one contained significantly more at 34 units/g and one was even more infectious but unquantifiable. These differences of inoculum content of soils, which were only partially corroborated by successive baitings of bulk soil through leaf fall, are discussed in relation to the timing of leaf fall, the activity of P. syringae and rainfall.