toxicity

[john lapointe]

Physan 27 use, which orchids is Physan toxic to? There is not a list with the bottle of Physan. I've heard read that it is toxic to Dendrobiums, are there others I shouldn't use it on? Thanks for input

[Ray]

In my experience, unless you apply it in too concentrated a dilution, Physan 27, a quaternary ammonium salt disinfectant, is not phytotoxic at all.

Phyton 20, on the other hand, is a copper-based systemic fungicide and bactericide that can severely damage many dendrobiums, and thin-leaved species like coelogyne, bollea, zygopetalum, and the like.

It is unfortunate that the two products have such similar names, as it can cause confusion.