Black spots and curl on Curry leaf

What happen to my plant?
I had cut down watering. But doesn't seems good yet. Any suggestions?

 

Would it be Murraya koenigii? (I've not seen red stems on one before.) If so, the thread What's wrong with my Curry Leaf Tree? (Murraya Koenigii) | UBC Botanical Garden Forums may be of interest.

 

Yea, it is Murraya koenigii. I did read the thread, but still....

 

It does look like insect frass, but I don't know. Have you seen any bugs around?

 

I doubt it is insect. Because I tried to remove it with no success.

 

Are the spots like those in these pictures? Apparently, the spots cannot be scraped off.

• www.flickr.com/photos/destrius/6246361995/
• www.flickr.com/photos/destrius/6246360965/

This plant has a leaf spot disease that's caused by the fungus Colletotrichum gloeosporioides but I can't seem to find any pictures of such an infected leaf.

 

I will try to get more picture tomorrow.
If it is the fungus per say, how you cure?

 

Ok, I hope these photos will help to tell...

 

The plant doesn't appear to be too bad off aside from having a few small black spots. I don't know much about this plant but I wonder if it would be better at this time to focus on possibly improving on the tree's cultivation; the leaves appear to be a much lighter green than those seen on other photos online, perhaps due to a nutritional deficiency. A stronger plant would have a better chance in coping with the ailment.