Friesia X, 4-5

FRIESIA . Bind X . Hefte 4-5 . 1974
CENOCOCC UM GEOPHILUM FR. IN ARABLE
SOIL IN DENMARI{
By HANS ARNE JENSEN
Danish State Seed Testing Station, Lyngby, Denmark
SUMMAR Y
An investigation of the seed content in Danish arable soil revealed
a large number of sclerotia of the imperfect fungus Cenococcum geophilum
FR. (syn. C. graniforme (Sow.) FERD. et WINGE) , which has
only once before been reported as occurring in arable soil (ELLIS, New
Jersey, USA., 1889).
By analysing soil samples from 57 fields sc1erotia of Ceno coccum
geophilum were found in all samples examined, For 37 of these fields
the number of sclerotia was determined at a depth of 0-20 cm. The
number of sc1erotia va ried between 0.07 mill. and 50.09 mill. per m",
and the average was 4.42 mill. per m-. The same 37 soil samples were
further examined for t he folIowing soil factors: Content of humus,
pH , specific conductivity, cation capacity, Na , K, Ca, Mg, Mn, Fe, Cu,
Zn, and P. The soil samples proved to be rather different ; fx. the pH
varied between 5.0 and 7.4 and the content of humus between 2.9 %
and 76.3 %. Nine of the 13 soil factors examined showed a significant
correlation between the values measured and the number of sclerotia.
However, none of the factors seerned to be the only determining
factor for the number of sclerotia present in the soil.
It is concluded that Cenoco ccum geophilum must be considered
common in cultivated soil in Denmark and probably also in other
countries with similar edaphic and climatie conditions.
INTROD U CTION
An investigation of the seed content in some Danish fields (JENsEN
1969), effected by mieroscopy of washed soil samples, disclosed a
- 300 -