I have something on the leaves of my sweet potatoes that looks and feels like...
I have something on the leaves of my sweet potatoes that looks and feels like sand. It becomes less visible when I try to rinse it off but does not come off - a few days later the leaf will turn yellow and brown and die. I cannot find anything described like this elsewhere.
Could you send a picture to this e-mail address: email@example.com? I suspect that you are observing edema which is caused by cells rupturing on the udersides of the leaves due to wide fluctuations in moisture.