I can't seem to find anything on the internet regarding my issue with my Colocasia Esculenta. A new leaf grew on my Colocasia Esculenta about 4 days ago. It looked healthy until today when I looked at the underside of the leaf. I noticed a blackish brown substance (doesn't wipe off) on the leaf vein. And on the leaf between these veins are 1/4 to 1/2 inch thin lines of the same blackish brown color. (Reminds me the color of car oil). I noticed the same thing happening to a relatively new leaf next to that one. Except it is on the stem. Does anyone know what caused this? Insect? Disease? Fungus? No chemicals have been sprayed, so that isn't an issue. I am clueless. Hope someone here can help.
