In vitro assays were undertaken to evaluate the control of two sapstain fungi, Leptographium procerum and Sphaeropsis sapinea by a combination of chitosan or chitosan oligomer (CODP-14) and a naturally mutated strain of Trichoderma harzianum. Spore germination and hyphal growth of the test fungi were assessed on media amended with chitosan or chitosan oligomer with and without T. harzianum using either simultaneous inoculation or various time intervals between inoculation of the media with sapstain fungi and inoculation with T. harzianum. There was no mycelium growth of the test fungi regardless of chitosan concentrations used when either L. procerum or S. sapinea were simultaneously inoculated with T. harzianum. However, the dose response of chitosan or chitosan oligomer on the test fungi was apparent when there was a time interval before the introduction of T. harzianum. There was a greater growth reduction at higher concentrations (0.075-0.1%v/v) and overall, chitosan oligomer was more effective than chitosan aqueous solution. Furthermore, the results also suggest that generally, either chitosan or T. harzianum alone was able to restrict or delay the germination of spores but the combination of chitosan and T. harzianum inhibited spore germination and hence colony formation of test fungi regardless of time delay.

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