Volume 12 Part 2 Article 76: Investigations on the Influence of Temperature on Growth and Spore Formation of Mycogone perniciosa and Verticillium fungicola, Two Pathogenic Fungi of The Cultivated Mushroom

Volume 12 Part 2 Article 76
Year 1989
Title: Investigations on the Influence of Temperature on Growth and Spore Formation of Mycogone perniciosa and Verticillium fungicola, Two Pathogenic Fungi of The Cultivated Mushroom
Authors: K. Bech, B.D. Jacobsen and G. Kovacs

Abstract:

A growth factor, easy to regulate in modern mushroom farms, is the temperature. So, by finding the difference between the optimum temperature used for the cultivated mushroom and the optimum temperatures for the two pathogenic fungi, Mycogone perniciosa (Magn.) Delacr. and Verticillium fungicola (Preuss) Hassebr. respectively, it might be possible to utilize this difference in order to reduce disease attacks. Here should, e.g., be mentioned the observations made during a visit to the underground mushroom growing galleries in the Loire Valley, France. Everywhere in the galleries there is a temperature of 15°C in the middle of June, and we were told that the temperature fluctuations throughout the year were + 1°C. This temperature is somewhat lower than the optimum demand in mushroom growing, which is 16-19°C according to the strain used, but the French growers were convinced that the comparatively less appearance of Mycogone and Verticillium was a consequence of the lower temperature.

No considerable difference can be expected between the temperature demand of the host and the demands of pathogens. It is a fact that, generally, a pathogen/host-relation is only possible in case their conditions of life, to some degree, coincide with each other. Varying conditions will soon be in favour of one party, soon of the other one, and it is up to the grower to influence these conditions in such a way that the host is “preferred”.

Lambert (1930) found 24°C to be the optimum temperature for mycel growth of Mycogone perniciosa, and Hsu and Han (1981) found 25°C as optimum for mycel growth, measured in colony diameters as well as in dry matter weight. The same temperature optimum was found for the spore formation. Fekete (1967) found 21-24°C to be the optimum temperature for Verticillium fungicola. Gams and van Zaayen (1982) have described three varieties of the species of Verticillium fungicola – two of them (var. fungicola and var. aleophilum) differing from each other, among other things, by having different maximum temperatures, viz. below 27°C and below 33°C respectively. Treschow (1941) found the amount of dry matter of M. perniciosa and V. malthousei (syn. of V. fungicola) after 30 days growth at a temperature of 22°C as optimum for both fungi.

Our investigations were partly aimed to find the shape of the growth curve as a function of the temperature. In addition to the optimum temperatures for the two pathogens, the maximum temperature and the lethal temperature interested us too, – the latter in particular because desinfection of growing rooms and tools might be done by heat treatment. Van Zaayen and Rutjens (1981) found the lethal temperature for M. perniciosa to be 48°C and for V. fungicola to be 38-39°C in aqueous spore suspension for 30 minutes. Already in our preliminary investigations we found for M. perniciosa a rather diverging value from the above, viz. 38°C.

Our investigations were carried out as part of a project: “Investigation on Sources, Ways and Conditions of Infection, caused by Mycogone perniciosa and Verticillium fungicola, on the Cultivated Mushroom”, with financial support from The Danish Agricultural and Veterinary Research Council (Bech, Jacobsen and Kovâcs, 1982).

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