You will have to gauge if the root system has died off or not. If you think there are no living roots then you will have to take a cutting and re-root. If the cutting is very dehydrated you will have to soak it, but seeing as there is evidence of fungal infection on the leaves this could make matters worse. Do you have a fungicide you can use? Even horticultural sulfur or cinnamon can be made into a paste and dabbed onto the spots.

In the winter you should be watering as you have in the summer as long as that is not on a schedule but in accordance to the moisture level in the pot. I admit that I often water on a schedule because I just have too many plants to do otherwise. Even though I water on a schedule I am watering at least once per week and I check the plants quickly in between to see if they need more water. If the pots you are using are not too big there should be very little chance of over-watering unless the growing conditions are under lit and cool/cold. If the plant is actively growing then it wants lots of water so don't withhold. It is true that some Hoya species really do want to dry out for part of the year but Hoya pubicalyx is not one of those so watering once the surface of the mix is dry is important.

I hope you can save this one, keep us posted.

Mike

Thanks, Mike.
Shortly after I wrote my message, I swabbed the leaves with peroxide and water. The fungal marks, which appeared to be the beginnings of circles, faded remarkably. I'm hoping that I caught it before it penetrated the leaf. Fortunately, the leaves are firm. A few are still cupped, but seem better than the other day.

Thanks for the comments on watering. I use the gritty mix and the water just pours through, but I let a little bit sit in the saucer - usually. All the others are doing fine, I wonder if I just missed this one on a watering occasion or two.

I was going to take it out of the terrarium, but decided to leave it there, but open the top and run a fan. You know that I'll keep a close eye on the plant.
Thanks again,
Gail

Too bad about your dragon woes, Gail. I'm glad it looks like you took control of the situation in time.

Just for the sake of 'misery loves company' I should tell you that I've been struggling with plants drying out unexpectedly this winter, too. Last winter I had the opposite problem and that made me gun shy and now, wouldn't you know it...

Heigh ho.