ABSTRACT
There is no universal method for storing plant pathogens. Some plant pathogens survive for long periods when dried in infected host tissues or agar cultures. Lyophilization, or freeze or vacuum drying are common methods used for long-term storage of microorganisms. Mineral oil storage is ideal for preserving bunt and smut fungi as long as the agar does not dry out and the seal is intact. Fungi can be stored in liquid Nitrogen as spores or mycelia, suspended in a cryoprotective solution. Preserving fungi by periodic transfer requires that: they be grown alternately on rich and poor media with a low carbohydrate content, at neutral pH and/or on media prepared from natural product extracts, such as plant materials. Organisms that survive cooling, freezing and subsequent thawing should store indefinitely in liquid Nitrogen. The Commonwealth Mycological Institute recommends using silica gel for long-term storage when lyophilization or liquid Nitrogen storage is not available.
