Is 'Systhane' Necessary in a Coffee Jar Propagator?

These fuchsia cuttings in a 200g coffee jar propagator were treated with 'Systhane' (myclobutanil) at full strength. Strange how there is no leaf damage, whereas the established cuttings kept in open pots suffered considerable damage, as reported earlier.

Since both varieties are the same ('Annabel'), it might be the high humidity which has saved them. In other words, perhaps the damage was done to the established cuttings by the tender leaves drying out with fungicide on them.

And, as mentioned elsewhere, it is interesting that these unvented coffee jar cuttings have not suffered with 'Botrytis' like the others did even after being treated with 'Systhane'. I wish I'd had enough cuttings to have taken an untreated control. I have had another jar of untreated cuttings running for two weeks without signs of disease. Is 'Systhane' treatment therefore necessary, or even effective?