C. maxima fungus? - Orchid Board

mykl · #1 07-09-2023, 08:25 PM

In June, a nursery near me had an open house. After this plant was home while I noticed these blotchy marks.
Is this mould or fungus or a poor buying decision on my part?
thanks

It is presently isolated, outside and should be getting good air flow if mould is the problem

Louis_W · #2 07-09-2023, 09:43 PM

Does the whole plant look like that?

I'd keep it isolated until you can see how new growth looks. I bet it's fine

King_of_orchid_growing:) · #3 07-09-2023, 09:49 PM

Actually, if you want me to be transparent...

Both.

I'll add that it is most likely a result of being grown in inappropriate conditions such as being grown a bit too cold.

It's very salvageable though. Leave it alone and grow like normal. This leaf will eventually fall off due to natural aging.

Grow intermediate - warm (65 F - 95 F).

Bright indirect light.

Moderate relative humidity (50% - 70%) is fine.

Water when roots are dry.

Don't cut any roots, btw. I'm aware of old cultivation practices with Cattleyas that are still in circulation as advice.

No need to cut living roots. In fact, don't. Roots are one of the plant's vital areas (specifically the root tip area).

Dead roots are ok to remove unless it has no living roots at all, then you may want to consider leaving some behind to anchor the plant in place.

---------- Post added at 05:49 PM ---------- Previous post was at 05:46 PM ----------

Quote:

Originally Posted by Louis_W

Does the whole plant look like that?

I'd keep it isolated until you can see how new growth looks. I bet it's fine

Agreed. Isolate for a few weeks too.

RJSquirrel · #4 07-10-2023, 12:11 AM

Ascomycete fungi from being too cold and too close to the swamp cooler

Sooty Mold on Orchids - Akatsuka Orchid Gardens

mykl · #5 07-10-2023, 07:42 PM

Thanks, everyone.
How a plant could be grown 'too cold' in Central Florida escapes me, but as mentioned it could have been by the swamp cooler. It shouldn't still be cold; we have been in the 90's (heat index 104) and very humid @ 88%. The great thing about you folks is I can get questions answered without having to wait until the monthly meeting at my orchid club - besides, I wouldn't want to bring an orchid that may transmit a desease to the plants being displayed.
Thanks again.

Roberta · #6 07-10-2023, 08:08 PM

I would suggest quarantine for a few weeks (keep it away form other plants) and then if the markings don't spread, it will be fine. ("Insults" that result in markings often stay for the life of the leaf, but if it doesn't spread, it won't do harm going forward). One way to watch for spreading is to use a black Sharpie marker, draw circle around the area of concern. It is then much easier to see whether the distance between the damage and the line changes, than to try to gauge an absolute change.

King_of_orchid_growing:) · #7 07-10-2023, 08:11 PM

It may or may not have happened in Central Florida. Unless it is possible to trace back all the places and all the environmental conditions the plant's been through before it got to Central Florida, (if it had been through other places prior), then it's hard to pinpoint with a high amount of accuracy specifically where and how it happened.

However, based on our previous experiences, generally speaking, cooler or cool and humid environments than what the orchid is able to tolerate that doesn't outright kill the plant tend to be the factors that cause this problem.

From what I know of C. maxima from personal experience, this is not a plant that's very tolerant of temperatures that drop to around the low to mid 50's F. This low end temperature can sometimes be a significant stressor to certain individuals within this species. i have attempted to grow this species outdoors here in Los Angeles all year round, and that failed spectacularly.

Roberta · #8 07-10-2023, 08:16 PM

Quote:

Originally Posted by King_of_orchid_growing:)

From what I know of C. maxima from personal experience, this is not a plant that's very tolerant of temperatures that drop to around the low to mid 50's F. This low end temperature can sometimes be a significant stressor to certain individuals within this species. i have attempted to grow this species outdoors here in Los Angeles all year round, and that failed spectacularly.

There's C. maxima, and then there's C. maxima... The lowland form, I agree, is definitely a warm grower. The highland form, on the other hand, does nicely for me outdoors. (It's just opening, will be a few more days before it's ready for a photo) This form is much more compact than the lowland version, smaller flowers but more saturated color.

King_of_orchid_growing:) · #9 07-10-2023, 08:21 PM

Quote:

Originally Posted by Roberta

There's C. maxima, and then there's C. maxima... The lowland form, I agree, is definitely a warm grower. The highland form, on the other hand, does nicely for me outdoors. (It's just opening, will be a few more days before it's ready for a photo) This form is much more compact than the lowland version, smaller flowers but more saturated color.

I didn't realize there were 2 forms of C. maxima (highland and lowland). The places I got them from a while ago made no such differentiation. Interesting...

Good to know.

The color variant I tended to go for was the var. coerulea.

Roberta · #10 07-10-2023, 08:52 PM

I think the coerulea variety is only found in the lowland form. Size is a big giveway... the lowland form tends to have leaves 10-15 inches or more, p-bulbs double the height. Highland form is about half that (Mine has leaves 6-7 inches, p-bulbs about the same). Got mine from Ecuagenera, Ivan assured me that it was the highland version (was still a young plant not quite fully grown) and he was right. Of course, the other way to tell is to see if they survive a chilly winter or two.

But that's the hard way...This one has been through 5 winters, so I think I got good info.