Brown
Germ
Precise cause unknown.
Turner (1981) has list twenty seven fungi associated with the diseaseof which Aspergillus spp. and Penicillium spp. Are most frequent . Many
are secondary invaders, as are bacteria spp.
Distribution
This disease is now
universal.
Symptoms
Brown spot appear on
the emerging button. These spread
and coalesce as the embryo
develops, and the tissues become slimly and rotten.
Control
The disease develops
most readily under moist conditions at a temperature of 38 - 40°C, use of the
wet heat treatment for germination therefore encourages its spread. Through sanitary
measures in the germinator may reduce incidence, the best method of control is
to adopt the dry heat treatment method
of germination (p.322), since the seed are dry when being heated at 39.5°C, and
when germinating they are at around 27°C, a temperature which does not
encourage the growth of the organism.