Sweet potato leaf weirdness

Any idea what this is? It's on one (only one) of my sweet potatoes. It looks a lot like the grains that gathered on the leaves when I did a test growing houseplants in salt water. The roots of the surviving plants pulled the salt from the water and it collected on the leaves like this. Eventually the salt eroded the leaves. I don't think this is salt, although it might be something from the tap water it's growing in. It's not hard, nor does it scrape off easily.

i see in your signature you say alkaline soil, utah, can there be alkali in the water?

Tereza Okava wrote:i see in your signature you say alkaline soil, utah, can there be alkali in the water?

Yes, the water is alkaline. Those in the greenhouse are being watered with runoff, those in the house are using culinary water. Out of 8 bottles in the house, only one is having this problem. However, the others are a different variety.

I’m starting sweet potatoes from saved tubers. I’m seeing this odd white crystal stuff on some of the leaves again. Does anyone know what this is? It seems to kill the leaves eventually. The plant usually seems to outgrow this.

found this:

Sweet potatoes are among the vegetables high in calcium oxalates, which can be exuded through plant pores (stomata) under certain conditions. It will form sand like crystals when it dries. The mechanism is not exactly like guttation in which a function of hydathodes exuding excess internal water.

Wow! Amazing find. I didn’t know they could do that.  I’ll do some research and see what is causing it. Maybe I have something out of balance

For me, they look like mineral deposits. Sweet potatoes, especially when grown in water, can sometimes pull lot of minerals from the water. These minerals will then crystallize on the surface. This happens more often if the water has a high mineral levels like calcium or magnesium... If it’s evaporating quickly, it will leave residues behind.

This is called intumescence.  I have sometimes gotten it trying to keep sweet potatoes growing as vines through the winter.  I did a bunch of deep research to find out what it might be.  It turns out that sweet potato plants need UV light to thrive, and this is a response to its deficiency.  Most windows block the UV.  I found that it helped to put the plants outside on any warm sunny day to get the direct sun when possible....this would be more difficult the further north one goes. Now I mostly have varieties that store well as tubers and sprout easily so I don't need to keep plants growing.