fusarium=death

[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.

[mvmgems]

Originally Posted by estación seca

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

Humidity ranged from 31-50%, daily temperatures 65-82F. It was in a 3" slotted pot with a mix of medium bark, perlite, clay balls, and sphagnum. I watered by soaking ~10-15min once or twice a week, and used the bamboo skewer + pot lightness to water once the skewer was barely damp.

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.

Wise words! There are so many orchids I'd like to tend, and only so much windowsill. I shall chalk it up to a learning experience.

Though as for fusarium occurrence, I'm not sure a low endemic rate in California necessarily rules it out? I only had this plant a few months and purchased from a grocery store who could have imported them from a tropical nursery (Hawaii or Taiwan). Given the short period of time I've had it, Occam's Razor would suggest it could have contracted an infection from the nursery and been asymptomatic until the multiple stresses involved in getting it to my home.

[camille1585]

Originally Posted by mvmgems

Though as for fusarium occurrence, I'm not sure a low endemic rate in California necessarily rules it out? I only had this plant a few months and purchased from a grocery store who could have imported them from a tropical nursery (Hawaii or Taiwan). Given the short period of time I've had it, Occam's Razor would suggest it could have contracted an infection from the nursery and been asymptomatic until the multiple stresses involved in getting it to my home.

While I also don't think your plant has fusarium, I agree with this comment. While we must not be too quick suspect fusarium, we should also be careful about being too dismissive of it as a potential cause. Like you say, plants travel, and can come from places where the disease is an issue.

That being said, I found a nice information sheet some time ago about orchid diseases including fusarium in Phals and Paphs, put together by a large commercial orchid nursery in the Netherlands. It's in Dutch, but google translate will do the trick.
HARK Orchideen - Bacterie-, virus en schimmelziekten aan orchideeengeslachten

Here is a quick translation:

Fusarium is mainly a problem in Phals and Paphs and can be considered an opportunistic pathogen, infecting/spreading when the plant is in a weakened state mainly due to issues such as very high fertilizer concentration, low substrate temperature, excessively wet substrate or sterilized substrate (due to lack of beneficial micro-organisms).

On Phalaenopsis, infections are first visible as small yellow-brown to reddish lesions on the roots. The spots gradually become larger until forming typical dark rotten sections of root. The base of the plant usually has black, dry rot which gradually spreads upwards, and in high humidity, pink reproductive fungal spores will form. The youngest leaves take on a reddish tinge, then chlorosis appears which leads to defoliation and death.

In Paphs the infection usually starts at the point where the roots and base of plant meet. A wet rot then develops with individual leaves easy to pull out. Disease development is slow and plants often form new roots on the healthy parts of the plant. However, the combination with slow delayed growth is a sure indication of fusarium.

[Shadeflower]

Thx Camille,
that is quite informative and confirms my suspicions that fusarium is not always a death sentence.
Your info states the plants can still grow new roots, the fusarium just hinders this. This would indicate a couple of orchids I'm suspecting have had it/have it might have it.
As long as the black area is kept dry it doesn't spread but some people recommend cutting all the black away which is very extreme and would certainly set them back.
I just discovered the one case this week after peeling away some dried sheaths which were completely hiding it and I am suspecting the plant has had it for months already based on its recent slow growing behavior.

But the area is being kept dry and I was debating to do more but I will leave it and see what happens. The plant is still growing I think and is starting to develop new roots above the black area