Winter is seed starting time for many gardeners. One scourge of seed starting are fungal diseases such as Pythium and Rhizoctonia. These diseases are commonly called "damping off" because they cause a sudden rot of seedling stems. Researchers with Agri Food Canada have experimented with using fish emulsion as a way to stop damping off disease from attacking vegetable seedlings.
Canadian researchers grew cucumber and radish seedlings in a peat-based, potting soil mix. One group was treated with a 4% fish emulsion solution. Another group received the equivalent dosage in inorganic fertilizer. Both groups were inoculated with disease spores and left to incubate 1, 7, 14, and 28 days in plastic bags. Cucumber and radish seeds were then sown in the bags for each treatment. Fish emulsion treated bags incubated for 7 days or longer, had a 70% to 80% protection rate from damping off disease. No disease control was found in the inorganic fertilizer treated bags.
This suggests fish emulsion is not only a good plant food for young seedlings because of its highly soluble form of nitrogen, but also helps create an environment that suppresses damping off disease.
For more on this research go to the Canadian Journal of Pathology web site at http://pubs.nrc-cnrc.gc.ca/tcjpp/k04-012.html