Biological Fungicide

[keithrs]

I guess my question is for the fairly advanced/experienced orchid lover.

I have inherited about 60 orchids from my father-in-law and found out that all 60ish orchid have root rot and/or crown rot from watering them in the same bucket and from the potting soils used. I have tossed about 15 or so because there too far gone. One cattleya hybrid is about 30 years old and would really like to save it(memories of his father attached). I have soaked it/them in Physan 20 for 10 mins and have Phyton 27 on the way.

My Question is on biological fungicides, Companion and Rootshield. I'm wanting to use these in stead of Physan 20 because of the whole natural thing.

Which one has worked the best for you and how do you use it?

I know that they are more of a protection barrier against fungi in stead of a treatment so to speak. Good fungi to kill bad fungi.

If there are other biological fungicides out there at are better, let me know.

Thanks
Keith

[orchidsamore]

I use Companion extensively but it has minimal effect as a fungicide. There is really nothing that actually kills fungus in the manner you think. Companion is an anti-fungal inoculate. Used over time it strengthens the plant to resist infections.

Root rot (pythion fungus) is not a big problem especially on Cattleya.

Remove the potting medium - let the roots dry (this is the best cure for fungus) and then you have two choices. Leave them out bare root until new roots begin to grow or re-pot into a very loose bark and charcoal mix. The more charcoal in your mix the drier the pot medium will be.

First you need to determine if you have pythion fungus or fusarium fungus. Fusarium can not be cured and must be removed.

Pythion starts as a black spot on the leaves and travels into the bulb and rots. It is easily cut off before it reaches the bulbs and an instant cure. Fusarium starts in the roots and shuts off the capillary action of water into the plant. You will see a darkening of the pseudobulbs from the bottom up.

Fusarium must be cut out of the plant by cutting from the fungal infection into healthy growth. You will have to remove some healthy growth as well. Keep cleaning your tools so as not to spread anything. Physan or bleach will work and clean often when working with sick plants.

If what you have is soft mushy roots from over watering, you may not have a fungal infection yet. Let the roots totally dry. Even if all the roots come off, orchids are strong and many will come back on their own.

Sunlight and drying are great sterilizers.

Python27 is a copper solution and will have minimal effect. It is the only compound this is weak enough to be sold to hobbyist. Stronger chemicals are very dangerous to use and again the all have very little effect in curing fungus. Mostly they are to prevent the spread to other plants.

[Eyebabe]

Pythium is killed by Subdue Maxx which is very expensive and most people either cut it out/off the plant or dispose of the plant. Pythium is highly contagious. Cleary 3336 is a good broad spectrum fungicide but does not kill Pythium.
I agree not a big problem for cattleyas...
My few cases of pythium however started in the rhysome area and traveled upward. You know it is pythium because the infection spreads so rapidly.
Pythium is often confused with Pseudomonas/Acidovorax which is bacterial AND a big problem for cattleyas. These water born organisms also attack usually from the top down and diseased tissue also can be cut out preferably before it gets down the pseudobulb to the rhysome.
Pseudomonas is killed with a copper based compound like Phyton 27.
Good luck!

One of the most useful links for me in deciding "what" my plant has and "how" to treat it:
http://www.houstonorchidsociety.org/...ySueBottom.pdf

[keithrs]

First, I want thank both of you for your responses!!!!

After reading that PDF that eyebabe posted, The best guide I've read!!!! I have just about everything on there as far as fungi gos... erwinia, acidovorax, and the biggest problem rhizoctonia are the main problems. I had one catt that had fusarium, but I tossed it.

All plants are unpotted, washed with Physan 20, dead roots and any other rot was cut off, than soaked in Physan 20 again for 10 mins. All the catts, dendros, and few others are hanging with loosely tied tie wire on a pole and I mist them with KLN about every 4 hours. All phap. and phal. are in new mixes that where soak in Physan 20 along with the pots, then repotted.

Man, What a job!!!!!!

Orchidsamore, Can I ask how you use Companion as far as amounts and time intervals go? Would you recommend using Physan in small amounts with Companion for short period of time?