How effective is physan? - Orchid Board

Orchidreamer · #1 10-21-2011, 10:44 PM

From your experience, how effective is physan in treating orchid rot? More specifically, black rot and soft mushy rot that seems to come back even after cutting. And yes I follow the sterilization and air circulation "rules" but

.

Also, how effective is physan when sprayed on healthy plants as a preventative? I'm having orchids that looked great a few days ago and now they're rotted away.

I hear it mentioned a lot, but I've never used it. I also heard from people that it's not strong enough to deal with rot, so I'm not sure if I should just skip it and go on to use Phyton 27?

Where is the best place to buy phyton 27?

rangiku · #2 10-22-2011, 02:45 AM

Sounds like you need Phyton 27. Physan 20 is a good disinfectant and preventative.

Take a look at this link for a comparison of the two: http://www.avsa.org/Library/20%20or%...r%20Phyton.pdf

I got mine online at kkorchids.com. They won't mail it if the temperature gets too low.

Masdyman · #3 10-22-2011, 06:02 AM

Preventative is better than cure in my opinion, I think as soon as rots set in you are on to a losing battle to recovery and these products are of little use apart from to limit the spread.
Better to do a periodic spray, this goes for using pest/disease control products.
So many people get the products out as a cure, I alternate between two pest/disease products and spray mist with Physan when I remember, and it is due! so thanks for reminding me. We cannot get Physan in the UK so I will probably have to look for a alternative.

fishmommy · #4 10-22-2011, 09:30 AM

I had no luck treating rot with Physan.
Phyton, however, did work.

marie09 · #5 10-22-2011, 09:43 AM

Hi,
One thing that works very well on rot caused by bacteria is hydrogen peroxide. A 3% solution like at the drugstore works very well.

Ray · #6 10-24-2011, 08:43 AM

Physan and hydrogen peroxide are topical treatments - i.e., they will kill what they come into direct contact with. Physan is an excellent preventive disinfectant.

Black rot (caused by fungi of the genera phytophthora and pythium) is a systemic infection, so will not be significantly affected by either of them; you need a systemic fungicide.

Phyton 27 is systemic, but the active ingredient is copper sulfate, which can be used as a herbicide, so some plants - notably dendrobiums and some "thin leaved" genera - do not do well with it. I recommend Cleary's 3336WP for a systemic fungicide.

Incidentally, if this is a recurring problem, it suggests your growing area is significantly contaminated, so a general dousing with Physan is probably in order.

orchidhope · #7 05-28-2023, 02:57 AM

Ray, I'm finding Cleary's 3336WP is discontinued. What's next best? After reading your comment, I canceled my order for Phyton 27 so I could order Cleary's. What took the place of WP?

THANK YOU!!

estación seca · #8 05-28-2023, 08:09 AM

Check your growing conditions. Plants aren't that susceptible to various infections if temperatures and relative humidity are correct.

Ray · #9 05-28-2023, 08:42 AM

Quote:

Originally Posted by orchidhope

Ray, I'm finding Cleary's 3336WP is discontinued. What's next best? After reading your comment, I canceled my order for Phyton 27 so I could order Cleary's. What took the place of WP?

THANK YOU!!

I was concerned about that myself, then out of the blue about 3 weeks ago, a long back-order of Thiomyl (generic Cleary’s) showed upon my doorstep.

I’m away until next week, but you can grab one now to secure it for shipment.