Cymbidium orchid leaves discolored. Fungus? Underwatered? Over watered? Please help
 

Hi
I received this miniature cymbidium orchid from someone who didn't have the time to care for it. It seemed ok but had a few scales on it. I repotted it a few weeks ago into a bark only (recommended for my region, Melbourne, Australia) and have had it in bright indirect sun since then. It tends to be a warm spot that's fairly humid as it's under a verandah. I sterilised the secateurs first with metholated spirits. I've watered it a few times a week since then, not allowing it to sit in water. It's dinner here and we've had some very very hot days. It developed these spots both on the ends of the leaves and on the body of some of the leaves and one turned yellow and soft. I don't know if I've watered too much, too little, or it has a fungus or other infection?? There were some nice green roots when I reported it as well as some dead ones, which I cut off. The origins of some of the roots have been visible between the ball as the bark has moved. Please help!

I don't see any particular problem. Those brown leaf tips tend to be caused by buildup of salts. Is your water particularly hard? Won't hurt anything. Also would not worry about those few spots on the leaves, unless they get soft and start to spread. The leaf in photo 5 does look like it may have some rot... you could cut it off and dust the cut with cinnamon, but it would be fine to just let it drop on its own (other leaves on that growth have already dropped). Leaf color indicates that it's getting plenty of light. I have found that a a bit of time-release fertilizer in the spring helps a lot. Since you are heading into autumn maybe wait on the time-release, but do keep fertilizing. You can expect to see new growth and new roots in late winter or early spring. So it may "sit there" for awhile.

Thanks Roberta.
So the rot is not necessarily something that will spread if I leave it? How good is cinnamon as an antifungal? I have eco fungicide that I have used for other plants - would it be suitable for orchids ? I think it's bicarbonate based.
Thanks

---------- Post added at 07:05 PM ---------- Previous post was at 07:03 PM ----------

Oh and the water is mainly from a water tank that collects rain water... So I wouldn't think it would be hard...?

Nmari - as a precaution - if you ever see any softening or rot near the BULB region ----- apply some fungicide such as Yates Anti-Rot Phosacid. Can easily get this from Bunning. But make sure it is mixed to the correct (right) proportions (ie. don't overdo it).

For your deep orchid pot - my recommendation is to put lots of big holes at the bottom of the pot. Use a cheap soldering iron from say JayCar if you have to ---- to burn holes through the bottom of the pot. Good air-flow from top to bottom of the pot (or vice versa) - through the media - and all around the roots ----- will help a lot to prevent fungal and rot issues.


Also, a potting media that restricts air-flow through the pot too much ----- can create issues like fungal activity, oxygen starvation of roots, rotting etc. inside the pot. So choice of media and size of media pieces should be considered.

Also - is your orchid pot sitting on a stand for preventing the bottom of the orchid pot from ever sitting in drained water? If there's no stand - then put some sort of grate or stand down the bottom, so that the bottom of the orchid pot (where the drainage holes are) never comes into contact with drained water. Allowing water to fully drain out of the orchid pot is very beneficial to the orchid.

For the orchid bark - use suitable orchid bark --- like orchiata bark.

Some kinds of bark may well contain something that could possibly negatively impact the health of the orchid.

Bright - indirect sunlight - should be no problem. Did you apply any fertiliser that could have possibly accumulated too much salt in the pot? Roberta suggested something like that already - and salt buildup will indeed lead to that sort of effect on leaves.

Warm and humid - no problem. Just make sure the veranda has some natural air-movement --- at least most of the time. Still-air for relatively long periods of time (- hard to say absolute lengths of time - but let's say half an hour, or even one hour, or more than an hour of next to no air movement) could possibly create issues for the orchid.

http://www.orchidboard.com/community...6&d=1580796842
Above: Along the bottom of the photo - Oncidium Twinkle and a couple of Oncidium Sharry Baby - growing very well in scoria.

My biggest concerns here are as follows:
1) Over potted in too large a pot.
2) Crown is not covered with mix. There are two new growths showing but if the plant is moving at all, the new roots will be deterred from settling down in the mix.
3) Although you have used a larger bark than I would deem required, I suspect you may be over watering. Newly repotted and divided plants benefit from a drier start than may be the regular routine as the roots have not established new growing tips.

That's my experience too.