Friesia X, 4-5

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included for Septoria passerinii SACC., this having been considered the
Septoria species most commonly attacking barley. Table 1 shows that
the pycnospores fall within the limits of L. nodorum, but are quite
distinct from those of S. passerinii. The ascospores also appear to
resemble those reported for L. nodorum on wheat.
Five isolates from barley leaves and five from wheat lea ves were
used for comparative observations of growth behaviour in culture.
The isolates were grown on a number of different media including
potato dextrose agar, oat meal agar, pea agar, malt extract agar and
lima bean agar. No significant differences in growth between isolates
from barley and wheat occurred on these media. Oat meal agar, pea
agar and potato dextrose agar proved to be the best media whereas
the growth on malt extract agar and lima bean agar was less vigorous.
On the first three of the media the colonies developed into white
masses of mycelium making a white, thick, vigorous mat which on
potato dextrose agar later turned dark olivaceous green. On oat meal
agar and pea agar there was less tendency to form dark coloured
pigments, and the fungus retained a light or slight pink colour.
As aresult of these comparative studies it is concluded that the
species on a morphological basis is L. nodorum.
PATHOGENECITY ON BARLEY
Infection experiments were conducted with three kinds of inoculum.
1) Pycnospores obtained from pycnidia on naturally infected
barley leaves. The spores were suspended in water supplemented with
0,1 % of gelatine. 2) Mycelial cultures obtained from diseased barley
leaves. Inoculum was prepared by macerating cultures on PDA in
water supplemented with 0,1 % of gelatine. 3) Mycelial cultures originating
from ascospores isolated from perithecia on barley leaves.
Inoculum was prepared as deseribed under 2.
The three kinds of inoculum were sprayed onto 14 days old barley
plants with an atomizer. Following inoculation the plants were placed
in plastic bags for 2 days and then transferred to normal greenhouse
conditions with temperatures at approximately 18-26 ° C. In the course
of 8 days after inoculation the plants developed disease symptoms
identical for the three kinds of inoculum. The fungus was reisolated
from the infected leaves and when these were placed in a moist
chamber typical pycnidia of L. nodorum developed in the lesions.
FRIESIA X 17