Ralph D. Arnold rarnold at
Tue Jul 11 03:08:04 EST 1995

I was asked to post this for someone presently without newsgroup access
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From: Peter Oei  <poei at>

One of the main oyster mushroom substrate producers has serious infection 
problems for months. Five to seven days after spawning an green mould occurs 
in all the bags, which was identified as Gliocladium flavum by dr. Geels of 
the experimenting station in Horst. The massive outbreak lets one to believe 
the infection occurs in the substrate preparation. Some strange things 
occured: when he switched from P. ostreatus to P. pulmonarius, things would 
go much better. But after having grown for some months the pulmonarius, he 
got the same problems. So he switched back to P. ostreatus, and things went 
better again. When he inoculated half a batch with ostr. and the other half 
with pulm, he found in the beginning that all the P. ostreatus would spoil 
and all the pulm would grow out well. later this pattern reversed. If straw 
was left unspawned then no infection would occur. The mould seems to 
parasitize the mycelium of the oyster mushroom, and being capable to 
adapting itself to another species of Pleurotus. It seems there is a 
feedback loop (reinfection at the farm), but several experts have failed to 
point their finger at a contamination source. Before spawning the spawning 
room is completely sterilised with H2O2, the room has absolute filters, 
hygienic measures at the farm are OK, so nobody understands where the 
infection occurs. The straw is brought in batches every two weeks, straw 
from several places has been used and found to give the same results. 

Substrate preparation takes place in a giant turning container (18 tons of 
substrate each time) The system worked fine for 7 years, excluding some 
problems with spawn containing bacteria. The straw is heated in a dry stage 
with steam and then cooled with cold water. The water is from a well 35 
meters deep. 

Does anybody know more about Gliocladium flavum or the above mentioned 
problem? More than 12 growers and their families depend on this substrate 

Please send comments to:
Peter Oei
poei at
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