SUMMARYChitin applied to soil naturally infested withF. oxysporumf.pisigreatly lessened the severity of wilt in Onward peas, sown at the time the chitin was applied to the field. In the glasshouse, different pea varieties sown in the field soil 8 months after the chitin was applied were protected equally against infection by any of the three races of the fungus. The severity of wilt decreased with increasing amounts of chitin added to the soil.Applying chitin to artificially inoculated soil a month before pea seedlings were planted in pots also greatly diminished the severity of wilt.Adding chitin to soil decreased the population ofFusariumand increased the number of actinomycetes. Many of the actinomycetes were antagonistic towardsFusarium.