Re Phsyan / RD20
Thu, 30 Jun 94 21:24:37 EDT

John Geiser asked about Physan and R.D.20. I have used both on my orchids
with good results, but I have never tried them on any of my CP. However,
I can answer the his question about their similarities-according to their
labels they are identical:
n-Akyl(60% C14, 30% C16, 5% C12, 5% C18) dimethyl benzyl ammonium
chlorides 10%; ammonium chlorides 10%; inert ingredients 80%.

The only difference is that RD20 says that is a greenhouse disinfectant
for orchids; Physan 20 gives instructions for use as a disinfectant for
swimming pools, dairies, hospitals and restaurants. BTW, the warning
on the label of RD20 is rather scary.

In his book on North American CP, Schell (1976) recommends benomyl for
fungus problems and none of my other books makes a recommendation for
the problem. I'd be a little wary about using benomyl now since DuPont
has removed its brand of benomyl (Benlate) from the market after losing
a number of lawsuits brought by commercial orchid growers a couple of
years ago.

Sorry I couldn't be of more assistance.