Toxic Seed Starting Flats?

gleneco1 at gleneco1 at
Sun Mar 17 20:45:57 EST 2002

Dear Marlin,
The material that is used to injection mould the trays is a "virgin"
polypropylene, and we have never had any problems with the plastic being
contaminated during the initial tray moulding process. However, we have
experienced major problems with root diseases in
Winstrip trays. We used the practice of washing the trays with a Chlorine
or other bactericide solution, and recycled the water for the washing. It
caused us to actually spread certain spores of fungal diseases 
to all the trays, and depending on the type of plant we lost many "plugs"
due to this infection.
The trays were sent to NC State laboratory, and the reports back were
clear that we had a devastating infection with all kinds of spores.
We have experimented with different chemicals, but did find that if they
would do the job of disinfecting, it would have to be a constantly fresh
solution. This would cause a large waste stream of environmentally very
aggressive liquid. As this would be unacceptable to our company and our
location in a Class IV watershed, we have switched our cleaning process
to a method using steam. The trays are placed in a steam chamber, and
the controls for the steam generator are set so that the trays will reach
a temperature of 160F, and then will be held for 40 minutes at a
temperature between 160F and 170F. After the steaming process we
shrink-wrap the stacks of trays, so they remain sterile until sowing. We
have had our trays tested again by NC State university, and contrary to
earlier tests with the liquid cleaned trays, we now have received
repeatedly a "clean bill of health" This shows also in the quality of our
plugs and continuing production this spring.
Hope this information helps you! Thank you for your email.
   Kathleen Lemkes.

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