Can anyone identify this Avocado Scourge?

[null]

I thought it was poor drainage, but after adding drainage holes and flushing the water through, it's getting worse, spreading to all the leaves of my young avocado. :/

 

[alp]

I can't, but have a look here

http://ucce.ucdavis.edu/files/datastore/530-27.pdf

Key in search control + f to find curved, brown patches.. to try your luck please. Hope this is useful.

https://www.helpfulgardener.com/forum/viewtopic.php?t=33663

Or phone a professional grower!