Collected Moss - Spray to prevent disease and insects?

Watched this wonderful, calming video on youtube showing collected moss being placed on a young maple. 春のミニ盆栽たち、モミジ、桜、ボケのミニ盆栽 4月の成長記録【Bonsai diary 盆栽日記 4/30】初心者の簡単盆栽の作り方 やり方 もみじ ミニ盆栽 苔 maple EOS R5 - YouTube

The bonsai artist sprays both the tree and moss to prevent disease and insects. Can anyone recommend a spray to use in this regard? I’ve always wondered about contamination when using collected moss. Have typically cleaned it in water prior to use but never did anything more.

I do not spray my collected moss before I grate it and combine with grated sphagnum for top dressing.

Why would you want to apply any broad spectrum spray (against insects and disease??) to a healthy tree? I guess it depends on your approach with pest and disease management. But the Japanese tend to be chemical heavy.

As you might tell from my original post, I prefer not to and have not to date. I do not spray trees “routinely”…only if/when absolutely necessary (due to fungus or insects). And even then I tend to use insecticidal soap or a mild fungicide.

The video linked to above made me question if the collected moss I tend to use could be contaminating my trees. Trying to gauge if introducing a pathogen or insects is a real concern or an unlikely scenario.

I have a hard time seeing the contamination topic. There is no thing such as a sterile garden environment. As long as you collect healthy moss which does not sit next to infected trees there should not be an issue. A healthy strong tree is the best approach.

Treatment makes sense for me if it is against a known and present issue. Drenching the root system just because can only have a negative impact on the rhizosphere and the symbiotic relations we sek to develop and foster there (see healthy tree remark above)

as always “imo”