The use of pH-indicators in diagnostic media for acid-producing plant pathogens

For simplified reisolation and accurate diagnosis of Sclerotium rolfsii on young cereal plants, agarmedia, containing bromocresolgreen as an indicator, CaC O3 as buffer, antibacterial antibiotics, Dexon and Benlate as selective fungicides and rose bengal as growth retardant, were developed and optim...

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Bibliographic Details
Published in:Zeitschrift für Pflanzenkrankheiten und Pflanzenschutz (1970) 1994, Vol.101 (5), p.498-507
Main Authors: Germeier, C. (Goettingen Univ. (Germany). Inst. fuer Pflanzenpathologie und Pflanzenschutz), Hedke, K, Tiedemann, A. v
Format: Article
Language:English
Subjects:
ASPERGILLUS NIGER
Biological and medical sciences
Biotest
BOTRYTIS CINEREA
BOTRYTIS FABAE
DOSAGE BIOLOGIQUE
ENSAYO BIOLOGICO
Ernaehrung
Fundamental and applied biological sciences. Psychology
Fungal plant pathogens
Fungi
Generalities. Techniques
IDENTIFICACION
IDENTIFICATION
Identifizierung
Kultur
MEDIO SELECTIVO
Methodik
Microbiology
MILIEU SELECTIF
Mycological methods and techniques used in mycology
Mycology
pH-Wert
Phytopathology. Animal pests. Plant and forest protection
SCLEROTINIA SCLEROTIORUM
SCLEROTIUM ROLFSII
TRITICUM AESTIVUM
USA
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Summary:For simplified reisolation and accurate diagnosis of Sclerotium rolfsii on young cereal plants, agarmedia, containing bromocresolgreen as an indicator, CaC O3 as buffer, antibacterial antibiotics, Dexon and Benlate as selective fungicides and rose bengal as growth retardant, were developed and optimized for several applications. Applicability and selectivity were tested with a spectrum of phytopathogenic and saprophytic fungi. Out of 25 tested fungal taxa, seven were differentiated by clearly delimited courts of indicator reaction around their colonies. Differentiation of strong acid producers was greatly improved when 0.2% CaC O3 was added to the medium. Five of these strong acid producers (Sclerotium rolfsii, Sclerotinia sclerotiorum, Botrytis fabae, Monilinia laxa and Monilinia fructigena) were important plant pathogens. Addition of the fungicide Dexon induced high selectivity for S. rolfsii and Aspergillus niger. The selective medium was appropriate to isolate S. rolfsii from non-desinfected culmbase pieces of infected wheat plants, and to quantify the viability of sclerotia of Sclerotinia sclerotiorum. High activity of acid production of several isolates of Botrytis fabae and B. cinerea correlated with strong pathogenicity on leaves of Vitis vinifera and Vicia faba. Acid production thus may be considered as a factor of unspecific aggressiveness. Some other isolates with no or low acid production were specifically virulent on beans, suggesting the involvement of more specific factors of virulence/resistance
ISSN:0340-8159