I just got my results back in from sending plant samples to Oregon State plant pathology testing. Three samples were tested, and these were plants from my last survivors of a big die-off from a few years ago. Two samples tested positive for Pythium, and all three were infected with Cylindrocarpon (Black-Foot Disease of grapevines). All three samples were negative for Phytophthora.
I have no doubt now they picked it up from soil contact and poor drainage in winter the way we had their pools set up. OSU is going to send me recommendations on control.
Everything I've read on these diseases is similar in that chemical controls are not very effective, and that good hygiene and isolation are key. Keeping trays and pots clean and sterile, good drainage, eliminate diseased plants, don't reuse soil, etc... are super important.
I have about a dozen of those original plants left. I'm going to treat those and pot them up separately and keep them in a location distant from my newer clean plants. Another horticulturalist has given me recommendations of Banrot and Subdue Maxx for treating Pythium.
Nacki, I haven't tried Rootshield yet, but I have some and will be using it, so I'll update this summer on how it goes. I've been a little hesitant to use Trichoderma since I discovered that it can be pathogenic to some sundews. Sundews, however, are very different from pitcher plants.
There are also the Trichoderma products from AmPac Inc. Many CP growers, particularly Heliamphora and Cephalotus growers swear by this product. The FAQs caution not to use the product on plants that have an active fungus infection however.
I can't say I've had positive experiences with the product. It seemed to promote fungal infections on both Cephalotus and Sarracenia. Other growers in the Los Angeles area report the same. Perhaps there is an indigenous fungus in the region that is resistant to Trichoderma and the Tricoderma reduces competing fungi. I had to resort to some heavy duty systemic fungicides to control the problem.
From my reading, different strains of Trichoderma harzianum (root shield) are effective for different types of pathogens. So you may be right about the resistance. I should look into AmPac. They use different species of Trichoderma.
It's interesting to hear that Rootshield had negative effects on sundews. I wonder how the negative effect works.