Section 6
Chapter 5,245

Effect of host substrate on germination and growth of verticillium albo atrum and verticillium dahliae conidia and mycelia

Pegg, G.F.

Transactions of the British Mycological Society 71(3): 483-490


Accession: 005244411

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The method of assessing fungal colonization of diseased plants by tissue maceration and colony counts was tested in recovery experiments using mycelium and conidia of V. dahliae Kleb. and V. albo-atrum Reinke and Berthold with tissue of chrysanthemum and tomato, respectively. Maceration of 1st internode chrysanthemum stem with mycelial propagules increased colony numbers 10- to 13-fold. Combined separate macerates of host and fungus were less stimulatory. Colonies derived from conidia in macerates were only slightly stimulated, or were inhibited. Non-host stems for Avena sativa and Bryonia diocia had no effect on growth. V. dahliae colonies from added propagules increased by 100% following maceration with infected chrysanthemum stem compared with healthy stem. Experiments on tomato tissue resistant (R) and susceptible (S) to V. albo-atrum showed in most cases an inhibitory effect on colony numbers. Healthy resistant near-isogenic tissue inhibited mycelial growth more than healthy susceptible. No propagules macerated with leaf or root of S and R isolines could be recovered. Colonization of S and R tomato stem based on colony counts was not proportional in each isoline to the level of inoculum used. The value of the plating method is discussed in the light of these results and the need to detect viable mycelium in systemically colonized plants.

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