Phalaenopsis leaf damage...cold? sun?

[Raqsharqi]

Our weather took an unseasonable dip, and our heater took an unappreciated delay. With the help of Christmas lights and enough candles to light a small church, we were able to keep the temperature in our new green house to no lower than 49 degrees. This morning, however, I noticed almost all the phalaenopsis have yellow spots, and a couple of them have what looks to be rotted leaf areas. I don't know if it is sun damage or cold damage or some other dam-age. I sprayed Physan 20 on all the spotted leaves just in case, but don't know what to do now. Thankfully, the heater is supposed to arrive today and night temperatures will be slightly warmer.

[lepetitmartien]

Check for Guignardia/Phyllosticta (fungus) on Sue Bottom's pdf (first on Orchid Pests, Orchid Diseases )

You have both forms round and diamond shape on the first pic. It may be the same on the second though I can't be sure for this one.

[Raqsharqi]

I don't think the second pic and the first have the same problem. The yellow blotches appeared all at once. If I cut off the damaged areas and continue to treat with Physan 20, can I save the orchids?

[Raqsharqi]

I performed major surgery on the orchids yesterday...cutting off any section of leaf with a sign of the fungus, sterilizing between cuts, and applying cinnamon to all the "mutilated" areas. It was heartbreaking, as some leaves were a good 8" long! The roots look good, and I put them all in the garage for the night, to be put outside in the shade once the day heats up. Is there a chance they will still survive? How long do I have to quarantine them? Outdoors won't be an option for much longer! Any other hints? I have to say, yesterday was one heck of a depressing day!

[bethmarie]

Sounds like a very rough day. You have my heart felt sympathy. I hope they pull through.

[lepetitmartien]

Sorry, I can't pass everyday, it's not my daily orchid coffee shop here.

For the fungus you did well. The necrotic zones are just spreading spores, the best is to remove them.

Orchids are tough, so a leaf off is not much a big deal, the leaf would have been dead at one not so far away point anyway…

A systemic fungicide would do good.

The second pic, I'm still in the mist… Multiple possibilites.

I'm just checking the 49°F (9,4°C)… It's very low for most Phalaenopsis. You should have a look into the cold ones like wilsonii, honghenensis etc. The hot ones (including most hybrids) should always be kept at 18°C or better. The second may just be cold issues.

For depression: I've clean up a bit my phals today and found quite some dead amongst the babies… it happens… Treated one plant for spidermites, found mealybugs happily installed on another… Cultivating orchids is also accepting some will die, sometimes for unknown reasons, usually because we make mistakes. I'm still paying the long time this summer without watering, never count on family for this…

Take it as a lesson, learn, observe, take measures to avoid it happening again.