Alright. We're about to nerd out.
CLAIM 1: Tissue Culture plants are just young and the acclimation process kills off the Thai Constellation.
We grow ~10 species from Tissue Culture. Given all the same environmental and chemical treatments, they survive at DRASTICALLY different rates. Varying disease resilience through a single species is very common. For example, in production of Caladium hortulanum, the following study proves the varying Pythium resilience in the same species, with root rot incidence rates of 35-94% in Eight cultivars, all the way to 5-14% incidences of root rot in three Cultivars. Source: https://edis.ifas.ufl.edu/publication/EP259
CLAIM 2: Pythium cannot survive the aseptic process of tissue culture
One way Pythium spp. reproduces is via oospores. (photo of Oospore here: https://cdn.shopify.com/s/files/1/2570/3692/files/Oospores.jpg?v=1688346786) Oospores are INCREDIBLY resilient, and can remain ungerminated UNTIL unsterile conditions exist. In the author's words: "Oospores are extremely durable and have survived for more than 10 years. Pythium spp. have survived passage through the intestinal tracts or earthworms, snails, and birds." This means they could ABSOLUTELY survive inside the Xylem/Phloem/Vascular system of a plant via the root, and live in the Tissue. Source of photo and quote: https://plantpath.ifas.ufl.edu/misc/media/factsheets/pp0053.pdf
Additionally, the Oospores remain dormant until nonsterile environmental conditions exist, then they germinate: "Oospores of Pythium ultimum were dormant, at first, but became increasingly germinable with time of exposure to nonsterile soil extract. Germination exceeded 90% after about 6 weeks in soil extract" p.1094 Source: https://www.apsnet.org/publications/phytopathology/backissues/Documents/1975Articles/Phyto65n10_1094.PDF
Also, oospores are resistant to Chemical Sterilants: "Oospores are also resistant to chemical
sterilants.(310)" Source: https://www.researchgate.net/publication/242625771_Etiology_and_epidemiology_of_Pythium_root_rot_in_hydroponic_crops_current_knowledge_and_perspectives
Further reading on oospores: https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/oospore
Additionally, Pythium exists in the tissues of hostplants, once they are cloned of the mother plant. "Pythium spp. are not seedborne, but they can reside in clonally propagated stock such as seed pieces of potatoes, sweet potatoes, sugarcane or transplants of strawberry." Source: https://plantpath.ifas.ufl.edu/misc/media/factsheets/pp0053.pdf
CLAIM 3: We are not in V2 of Thai Constellation.
We might be in V54 of Thai Constellation tissue culture. I don't know. But I can tell you, and many other Thai Constellation growers corroborate that this batch has LESS resilience to root rot causing parasites.
Tissue plants come from other tissue plants. They all originate from initial chunks of monstera stems, usually with axial buds (because of the size of the plant).
After multiple years, it IS possible there is some form of genetic breakdown/mutation occurring which is being displayed as a susceptibility to root parasites. (Source for genetic drift in asexual propagation: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3686192/
Compared to previous 2018 versions, as well as Monstera deliciosa (unvariegated), philodendron tortum, philodendron paraiso verde, and musa etc etc they survive at drastically lower rates. I'll do a side by side batch for you.
CLAIM 4: It's not even Pythium.
You're right. It might be Fusarium, Phytophthora, or Pythium? I can't definitively say, but I'm losing Thai Cons via a blackening (wettening) of the stem (see video here: https://cdn.shopify.com/videos/c/o/v/705aa86a4be747d9be3d6774bbdb3f63.mov
This looks like classical damping off caused by Pythium. But it's probably time I turned on my microscope :)
My infections look like the ones described below.
"Often, infections from Pythium spp. have a greasy or water-soaked appearance in the plant tissue because of leakage of the moist cellular contents from plant cells that occurs from the enzymatic activity mentioned earlier. " Source: https://plantpath.ifas.ufl.edu/misc/media/factsheets/pp0053.pdf
CLAIM 5: I'm saying Thai Con has issues so that I can keep prices high?
If anything, it's made us sell less Thai Constellation. It's like saying "Calatheas get spider mites". They do, and it increases their wholesale price to retailers. And it would make a retailer sell less of them if they said this.
