Hi ! The query was founded about the fungicides. The eveidence is in the back rotted roots in the pics. Which exact pathogen is not evident.

All of the products you and other people are talking about are well documented to help control specific problems. They are NOT poisions if applied correctly for the problem. Problem is to get a right diagnosis. Ive been growing for over 30 years in many locations and used all of them with success on orchids. Good luck to 'Tolumnia' with the plants!

I think the number one lesson everyone should learn is quarantine all new arrivals to your collection! I always keep the new plants lumped together. So there is no possibility of water spattering from new plants to my collection. I tend to the collection before I ever touch the new ones. They are the last on the list for anything.

I think Martin Moates says it best:

He does advocate a proper spray program of fungicides.

To answer the questions directed to me --

I use three natural products (Companion, Essentials -rooting hormone- Vermi-liquid worm secretions added essential microbes), the most effective for fungal control is Companion brand of Bracillus bacteria made from seaweed. There are other products that use bracillus bacteria in different combination and I assume they all work about the same.

It does not kill fungus and I personally do not believe any of the products effectively kill fungal problems. Bracillus bacteria is natural anti-fungal inoculate. It stregthens plants to resist the disease. The best cure is to never get the problem.

After using Companion for three years I went from destroying 380 seedlings (out of 4000 new ones) three years ago to 80 the next year to zero the third year. This season despite twice a day rains including a rain after dark each day (everything is outside under shade cloth) I have destroyed only 6.

Fungicides are applied commercially as a preventative mostly to control spreading from an infected plant to healthy plants. Diseased plants are destroyed not 'saved'.

The biggest problem with hobbyist use is that the items offered for sale have been used for so many years the fungi have evolved to be resistant to the products.

What hobbyist fail to realize is that these products are not to be used more than twice a year. Commercially, if more treatment is desired, the products need to be rotated between at least three different types of fungicides. That does not mean three different 'names' but three different classes of drugs that work differently.

The newer drugs are effective to prevent spread but very expensive. Heritage is the best but $600 a pound. Even with 12,000 orchids and new purchases every week, it is not commercially viable for me. Destroying diseased plants is the economical method.

For hobbyist the best and least expensive treatment is a fan. Good air circulation is the best prevention.

Being a hobbyist I care more about _not_ destroying plants than I do economy. That is why for use as fungicides I have chlorothalonil, mancozeb, myclobutanil, thiomyl, Heritage and Captan.

For miticides I have abamectin, Floramite, Tetrasan and Talstar.

For insecticides I have azadirachtin, abamectin, spinosad, imidacloprid and Talstar.

and what do you use for all the nervous twitches you have from using all these chemicals?

This thread has gotten me to produce a tutorial with photos of fungal issues. You can find it on my web site

Pythhion and Fusarium fungus on Cattleya

I think that for the fear-mongers the best quote is from George Carlin: "Saliva causes cancer, but only if swallowed in small amounts over a long period of time..."

...um..you all just swallowed again.

Wow this thread has turned so interesting. Thanks for all of the feedback!
If you had plants that looked like this what would be your guess as to they problem? I should note that since the weather has gotten REALLY hot and dry (which means I am watering with the hose every day) the problem seems to have stopped progressing. Even on plants that had it but have not been treated in any way. And all of my plants have been putting off new healthy roots like there is no tomorrow. I think this officially rules out the water as a problem.

I'd love to hear something about fungicides that are easily available in Canada. By that I mean something I can purchase here rather than ordering from the US. Any good suggestions?

:)