fusarium=death

[mvmgems]

Speaking about fusarium, I’ve had this phal that’s been sickly since I got it two months ago. Looked like root rot from the dense sphagnum, so I repotted it in bark/moss. It’s only declined since with very wrinkly, but not leathery, leaves. Checked the roots today and all but a half inch was dead. Upon cutting found two purple rings, one thick on a freshly dead root, and a faint one on a more dried out root. No trace of purple on the leaves otherwise, though the flowers were pink-purple. I trashed it.

Would you attribute this to fusarium?

[estación seca]

Originally Posted by mvmgems

Speaking about fusarium, I’ve had this phal that’s been sickly since I got it two months ago. Looked like root rot from the dense sphagnum, so I repotted it in bark/moss. It’s only declined since with very wrinkly, but not leathery, leaves. Checked the roots today and all but a half inch was dead. Upon cutting found two purple rings, one thick on a freshly dead root, and a faint one on a more dried out root. No trace of purple on the leaves otherwise, though the flowers were pink-purple. I trashed it.

Would you attribute this to fusarium?

Not enough information. What were your temperatures? Humidity? How were you watering? That looks like a struggling Phal whose root zone was too dry.

[estación seca]

What symptoms are your plants showing?

What are your growing conditions? Temperatures day/night? Humidity? Light? How are you watering?

[Coolbabe]

Thank you. I appreciate what you said. I don't feel so lost and stupid. I am nit buying anymore orchids right now. I have relocated some that have never bloomed. And I think I need to leave them alone more. It's my personality to "love" too much.

[Leafmite]

Yes, I have been through it so I understand the distress that you feel. I did really great with the orchids for many years before the Calcium deficiency 'Black Plague' (around 2005/2006?) but after my own string of orchid tragedies, I just grow some mini-Cattleyas and a few favorites... currently, a total of around thirty-five orchids. I find some orchids are really worth growing so I will probably always have those but never the large collection that I once had.

I have other tropical plants that I find very rewarding so I have been focusing on those more lately. Orchids are nice but they do not produce delicious fruit and they are not nearly as wonderful as Jasmine sambac.

[Clawhammer]

Originally Posted by Leafmite

Yes, I have been through it so I understand the distress that you feel. I did really great with the orchids for many years before the Calcium deficiency 'Black Plague' (around 2005/2006?) but after my own string of orchid tragedies, I just grow some mini-Cattleyas and a few favorites... currently, a total of around thirty-five orchids. I find some orchids are really worth growing so I will probably always have those but never the large collection that I once had.

I have other tropical plants that I find very rewarding so I have been focusing on those more lately. Orchids are nice but they do not produce delicious fruit and they are not nearly as wonderful as Jasmine sambac.

I just bought 3 sambacs! (Belle of India, Maid of Orleans, Grand Duke).

[Leafmite]

Originally Posted by Clawhammer

I just bought 3 sambacs! (Belle of India, Maid of Orleans, Grand Duke).

You are going to really enjoy them!

---------- Post added at 10:01 PM ---------- Previous post was at 09:40 PM ----------

Originally Posted by Roberta

I have seen "purple rings" when dividing high-anthocyanin (red/purple) plants that were perfectly healthy. And fusarium is very unlikely in my dry climate. So the purple-ring thing is not likely to be an indicator of anything. That was a Miss Orchid Girl video made some years ago. I think that she has learned better in recent years but the videos are still around. (Stuff on the Web tends to stick around forever)

She seems to indicate that something went through her orchids and did a mass eradication.... I have heard of fusarium doing that to other collections in the past. It can be very discouraging when it happens. A good systemic fungicide like Clearys 3336F Fungicide is the only thing that can stop it. I know that I nearly gave up orchids after I lost so many to Calcium deficiency (some fungus just went right through them).

[Roberta]

I have seen "purple rings" when dividing high-anthocyanin (red/purple) plants that were perfectly healthy. And fusarium is very unlikely in my dry climate. So the purple-ring thing is not likely to be an indicator of anything. That was a Miss Orchid Girl video made some years ago. I think that she has learned better in recent years but the videos are still around. (Stuff on the Web tends to stick around forever)

[Roberta]

Fusarium mostly occurs in tropical areas. In northern California, I doubt it very much. Root rot from bad sphagnum? Very likely. The wrinkly leaves are indicative of the plant not taking up water - which is what happens when the roots are dead. (Underwatering can do that too, but here, I think it was the bad roots making it impossible for the plant to get water, even if the medium was wet. ) Looking at the stubs of roots, I doubt very much whether it was salvageable, at any rate. If there WAS a viable root, cutting it removed that option, however. But if it was in poor condition when you got it, chances are that it was on its way out from the beginning, from poor culture long before you got it. Time for a new, healthy plant to give you pleasure and a good chance for success.

[mvmgems]

Originally Posted by Roberta

Fusarium mostly occurs in tropical areas. In northern California, I doubt it very much. Root rot from bad sphagnum? Very likely. The wrinkly leaves are indicative of the plant not taking up water - which is what happens when the roots are dead. (Underwatering can do that too, but here, I think it was the bad roots making it impossible for the plant to get water, even if the medium was wet. ) Looking at the stubs of roots, I doubt very much whether it was salvageable, at any rate. If there WAS a viable root, cutting it removed that option, however. But if it was in poor condition when you got it, chances are that it was on its way out from the beginning, from poor culture long before you got it. Time for a new, healthy plant to give you pleasure and a good chance for success.

Hi Roberta,

I was pretty curious about the prevalence of fusarium in orchids after your comment, which surprised me since fusarium blight is a familiar issues here in California with many different species of ornamental, vegetable, and crop plants.

I did find a couple of useful scientific resources, though some are paywalled. Since I'm a molecular biologist by training, and with brief experience in a pathogen research lab, this is right up my alley for a fun evening's reading haha.

This open-access article from 2002 describes the incidence of fusarium infection in Phalaenopsis cultivated in greenhouses in Korea (which has a temperate climate) as up to 30%. If fusarium does indeed favor warm, humid tropical conditions, it's possible that the microclimate of a cultivation greenhouse promotes its pathogenicity.

This review of Fusarium in orchids from 2018 is much more comprehensive, though paywalled. Contact me if you'd like the full text copy. Notable highlights for me included:

"In 2015, the largest state producers of potted orchids were California ($118.5 million), Florida ($77.8 million), and Hawaii ($11.3 million), while for cut flower production California ($6.1 million) was the largest producer followed by Hawaii ($1.5 million)." I had no idea most modern orchid production in the US was in California! I would have guessed HI/FL.

"Fusarium is associated with orchids as both pathogens and non-pathogens throughout the world. The non-pathogenic Fusarium species associated with orchids are usually decomposers (Booth, 1971) and/or mutualists, which aid seed germination and seedling coloration (Vujanovic et al., 2000). Non-pathogenic species of Fusarium can be used to control Fusarium wilt on various crop." I hadn't fully appreciated the diversity of Fusarium species and strains, and how certain species are beneficial and may protect against pathogenic species/strains.

"The incidence of Fusarium diseases in orchids has been steadily increased worldwide, and pathogenic Fusarium spp. are now considered one of the major limiting factors for the production of high quality orchids (Wedge and Elmer, 2008)."

"Fusarium pathogens of orchids have been reported from locations around the world, although the majority of the reports originate from tropical and subtropical regions (Table 1)." Roberta, is this where you drew your information? The table draws from studies from 1996 to 2015, so it's relatively recent information.

"Fusarium oxysporum is a complex species composed of at least 150 host-specific, phytopathogenic species (refs) and a vast number of sapro- trophic strains. Due to a relatively high level of biodiversity in this species, it has the ability to adapt to environmental changes and form new pathogenic strains over a short period (White et al., 2001). It is also the most economically important species in the Fusarium genus, given its numerous hosts and the level of loss that is produces on infected plants." So as orchid cultivation centers shift to include temperate countries, it's quite plausible that orchid-specific strains would adapt to the new host-environment conditions.

"The recent rise in the popularity of orchids as a global crop, has been accompanied by a rise in disease incidence on the crop. Movement of orchids from countries where diseases are prevalent, to countries where they were previously not known to occur is an unintended consequence of the global trade. In many countries such as the United States, strict measures are in place to inspect imported plant material and prevent the entry of new pathogens. However, many plants produced in Taiwan and South-East Asia, that have been allowed into the United States, were contaminated with low levels of Fusarium (Kawate and Sewake, 2014)." Looks like my conjecture wasn't off-base!

Then there's a useful section on management techniques tailored to greenhouses, including setup, culture, breeding of resistance, and appropriate fungicides. But the coolest to me was using bugs to fight bugs: "Biological control is another area of disease management that needs further research for orchids. Pseudomonas fluorescens as an antagonistic agent in the soil, effectively suppressed F. oxysporum f. sp. vanillae. A combined inoculation of Trichoderma sp. and Pseudomonas spp. also was effective against Fusarium wilt of vanilla (Tombe et al., 1997; Sandheep et al., 2012)."