Dendrobium Frosty Dawn 2 new canes after bloom and other issues.
 

Well, here is a little background. I got my Den Frosty Dawn last year around late Sept. It started to bloom around Feb and it is still blooming now. It went through several blooming stages.

Now, there are 2, yes 2, new baby canes growing by the most recent cane. They start to grow leaves now. Unfortunately, one of the taller baby canes have a single rotted leaf. My question is that what else I could do to prevent the new leaves from rotting? Keeping the humidity drier? Less water contact? The Den is inside my grow tent and the humidity is often around 90% now..is hot in NYC.

I want these 2 new canes to mature into nice looking canes with leaves all over. When I first got this Den, it was losing leaves already from the bottom.

90% with hot temps it's not suitable for your plant.
The recommended humidity is between 50~60%.
90% is the ideal condition for fungus and all related problems.
At least do you have a fan going on inside the tent?

Yes...2 of them... The hot temperature didn't harm my orchards at all...have total of 6. In fact, I have 2 oncidiums growing with flower spikes now. I have these 2 for about a year...

Oh the Den is actually in the direct air flow my fan....the fans are powerful. I can see leaves moving.

My advise is to lower the humidity to 50-60% max.
Let's see what others have to say.

The tent isn't sealed. There are air exchanges and opening on the side. I think the rot on that particular young leaf may have something to do with me spraying water to them when I water the orchard. I use a 1 gallon water sprayer. I will try to avoid watering on the leaves.

The only issue I am worrying is that the new cane won't grow just because some of the newer leaves are rotting away. On the other hand, there is a nice US penny size leaf which didn't experience any rotting.

Dying leaves often happen when Dendrobiums are kept too hot and too humid. It isn't caused by water on the leaves. In habitat rain falls on the leaves all the time.

Frosty Dawn is a hybrid of species in the Formosae section of Dendrobium. In general they don't like hot weather. The species seem to do better with a cool-down at night.

H&R Nurseries in Hawaii hybridized this, and they have it for sale now. They label it as W-I, meaning warm to intermediate.

Hot and very humid for orchids not liking heat is a recipe for disaster. Almost no orchids in cultivation require 90% humidity. I agree it is just asking for trouble. Dropping it will greatly lessen your risk of fungus in a heat-stressed orchid.

Here is an update. The weather in NYC has been cooler and I managed to lower the humidity between 70% to 80%. The rots stopped or at least they are not on the newer growths. The leave's condition didn't get worst. I had to trim off the affected area on the leaves. However, they are still growing. I am already seeing new leaves growing and hopefully they would look healthier. I thought it is odd that I have two new canes growing at the same time. When they matured, I guess it means I would get lots of blooms.... :)

Great news! This is supposed to be a very vigorous hybrid that grows fast, and makes lots of new growth.

I hope so...will continue to monitor the new canes. I noticed that the flower buds closer to my grow light (6 florescent LED bulbs) are sprouting with 4 to 5 blooms or 4 to 5 flowers per flower spike. Is just amazing that the main and newer cane is still blooming since Feb. Most of them have withered away though.