Seed Testing of Maize and Wheat A Laboratory Guide - Search ...

Detection technique
Freezing blotter method
(See Annex A)
References
CM!. 1971 . Descriptions of
Pathogenic Fungi and Bacteria
No. 309. Micronectriella nivalis.
CAB, UK.
Nath, R., Neergaard, P. , and
Mathur, S.B. 1970. Identification
of Fusarium species on seeds
as they occur in blotter test.
Proc. Int. Seed Test. Assoc. 35
(1): 121-144.
Wiese, M.V. 1977. Compendium
of Wheat Diseases. APS Press,
USA.
Zillinsky, F.J. 1983. Common
Diseases of Small Grain
Cereals: A Guide to
Identification. CIMMYT, Mexico.
Colonies are white to pale peach
to apricot with sparse or cottonlike
tufts or felty mycelium. Colony
on seed has very loose mycelium
along with numerous orange
spore masses which are irregular
in shape and size. The mycelium
appears a little pinkish due to the
development of spore masses
along the hyphae. The spore
masses appear circular, smooth
and rather 'dry'.
Conidia are hyaline, short, curved ,
with a pointed apex and flattened,
wedge-shaped base, 1 -3 septate,
but most frequently 1 septate, and
measure 10-30 x 2-5 IJm.
Chlamydospores are not present.
Perithecia are initially white, but
become pink and finally
greyish-black. They are oval to
spherical, and measure 100-150 x
120-180 IJm.
Asci are hyaline, club-shaped, or
occasionally cylindrical, thinwalled,
6-9 x 60-70 IJm and
normally contain 6 to 8
ascospores.
Mature ascospores are hyaline, an
oval curve, 2- or 4~celled and
measure 3-5 x 10-17IJm.
M. nivale is readily identified by
1-3 septate, short, curved conidia
tapering towards the ends, and
with foot cells not well-marked.
M. nivale is distinguished from
M. dimerum, by the following :
a) Generally M. nivale has more
abundant mycelium than
M. dimerum.
b) M. nivale mycelium is pinkish
due to the production of spore
masses along the hyphae while
M. dimerum mycelium is white .
c) Spore masses in M. nivale are
circular, smooth and rather
'dry', while in M. dimerum they
are flat, slimy and very irregular
in shape.
d) M. nivale conidia are longer
and always septate.
e) M. nivale does not produce
chlamydospores.
f) M. nivale grows and sporulates
best at temperatures of 18 2 C or
lower.
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