Improved selective medium for isolating Cylindrocladium crotalariae microsclerotia from naturally infested soils

Area of Science:

• Mycology
• Plant Pathology
• Soil Microbiology

Background:

• Fusaria and other fungi often inhibit the accurate identification of Cylindrocladium crotalariae on soil-dilution plates.
• Previous methods required soil treatment with sodium hypochlorite (NaClO) to control competing microorganisms.

Purpose of the Study:

• To develop an improved soil-dilution medium for enhanced recovery and recognition of Cylindrocladium crotalariae.
• To eliminate the need for pre-treatment of soil with NaClO.

Main Methods:

• Supplementing a sucrose-TBZ medium with three quaternary ammonium compounds.
• Replacing peptone with tyrosine in the culture medium.
• Increasing sucrose concentration to achieve a water potential of -10 bars, creating the sucrose-QT medium.

Main Results:

• The new sucrose-QT medium significantly reduced the growth of competing fusaria and other undesired fungi.
• Recognition of Cylindrocladium crotalariae colonies was improved on the sucrose-QT medium.
• The sucrose-QT medium eliminated the necessity of using NaClO for soil treatment.
• Increased recovery of C. crotalariae microsclerotia was observed from all 16 naturally infested soils tested.

Conclusions:

• The sucrose-QT medium is effective in suppressing undesired fungi, thereby improving the selective isolation and detection of Cylindrocladium crotalariae.
• This enhanced medium offers a more efficient and direct method for assessing C. crotalariae populations in soil samples.