Biological control of Botrytis spp. by Ulocladium atrum : an ecological analysis

Research output: Thesisinternal PhD, WU

Abstract

<p>Plant pathogenic fungi from the genus <em>Botrytis</em> cause economically important diseases in a wide range of crops during the production phase as well as post harvest phase. Control is based on the frequent use of fungicides. Alternative approaches for control are studied because of the development of fungicide resistance in the pathogen and environmental concerns.</p><p>The fungal saprophytic antagonist <em>Ulocladium atrum</em> is an effective biological control agent of <em>B. cinerea</em> in cyclamen. <em>U. atrum</em> may also be effective against <em>B. cinerea</em> in other crops and against other <em>Botrytis</em> spp. The biocontrol effect of <em>U. atrum</em> is based on a competitive interaction with <em>B. cinerea</em> in plant tissue. An immuno-histological technique was developed to visualize the interaction between the mycelia of <em>Botrytis</em> spp. and <em>U. atrum</em> in plant tissue and quantify colonization levels. Nutrient competition was found to be the dominant antagonistic mechanism between the species and pre-emptive colonization of plant tissue by <em>U. atrum</em> was identified as the most promising biocontrol strategy. Necrotic plant tissue is the primary target for <em>U. atrum</em> applications, since this is the (only) niche available to both <em>Botrytis</em> spp. and <em>U. atrum</em> .</p><p>Pre-emptive colonization of naturally necrotic tissue by <em>U. atrum</em> was highly effective against <em>B. cinerea</em> in cyclamen, whereas <em>U. atrum</em> applications against <em>B. elliptica</em> in lily were ineffective. A comparison of both pathosystems suggests three criteria that govern the potential success of <em>U. atrum</em> as a biocontrol agent. 1) There must be a niche in which <em>U. atrum</em> competes with the pathogen; 2) The competitive ability of <em>U. atrum</em> in this niche has to be sufficient to allow for competitive exclusion of the pathogen. 3) The niche from which the pathogen can be excluded has to be essential for disease development. Colonies of <em>U. atrum</em> have lower radial growth rates than those of the <em>Botrytis</em> spp. studied. In practical biocontrol, this competitive disadvantage of the antagonist can be overcome by applying a high density of its conidia in a uniform distribution on the target tissue.</p>
Original languageEnglish
QualificationDoctor of Philosophy
Awarding Institution
Supervisors/Advisors
  • Rabbinge, R., Promotor, External person
  • Koehl, J., Promotor, External person
  • van der Werf, Wopke, Promotor
Award date1 Dec 1999
Place of PublicationS.l.
Print ISBNs9789058081490
Publication statusPublished - 1999

Keywords

  • botrytis cinerea
  • plant pathogenic fungi
  • biological control
  • deuteromycotina
  • mycelium
  • dematiaceae

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