I made an account just for this topic.
Kinda sorta old, but out of interest. I found a review article that can help with more data.
I like to dive into things pretty far. That paper is a really good general idea of oligochitosan and the mechanisms proposed in 2016.
According to them, they proposed that oligochitosan should be used as early as possible and even went as so far to say that rapeseeds could be coated with this. The earlier the plant has an interaction with oligochitosan, the better the chance of creating a resistance to diseases. This is one point to support their "vaccine" idea.
Botrytis cinerea
Cucumbers were treated with oligochitosan 1, 4, and 24 hours before introducing grey mould. The decrease of grey mould went down 65%, 82%, and 87%, respectively, with usage rates at 50μg/mL. I believe this to be a spray.
I need to read more, but a ladder study of concentrations, molecular weight, and deacetylation degree would need to be done. I bet sourcing that would be expensive. Instead of doing all that maybe something has been written about for X diseases in hops or hackberries due to them being so closely related to cannabis. Or you know... hemp.
One thing I wonder about is would it be effective to spot treat leaves in flower and a result being worth the effort versus the possible amount needed for a root drench. Kind of similar to how someone might polish a plants leaves, but with oligochitosan. Usually theres a "wet effective time" on somethings. Ex. Disinfecting agents are only as good as the length of time the surface was treated wet. Perhaps there would be a time needed for the plant to intake an effective amount. I wouldn't be smoking it because its on a shade leaf. Searching for Py-GC/MS data on oligochitosan would give a good idea on what is being made after burning to see how bad it can get. Damn shame I didn't think of this while I had access to that instrumentation.