Question
I have a beautiful fruitless mulberry tree which has a rust-like appearance around the leaves. It looks like it is turning for fall but it's not fall weather here in Yucca Valley yet. Next to the mulberry we have a necturine which
is completely naked of leaves too. It bore fruit this year, which the birds ate. I suspect that whatever happened to the necturine is happening to our mulberry. Both trees were leafy and beautiful then almost over night this happened.
Answer
This sounds like a rust fungi. Mulberry rust is common in China where they raise silkworms on mulberry leaves. It is not really a serious leaf disease as far a causing the tree any health problems. It may cause some of the leaves to drop early. The only control I could find was the use of a fungicide but this would have to be sprayed on all the foliage weekly in the spring for about a month. It does not seem very practicable in your case. I would not really be too concerned about this rust disease on the leaves. For a rust to infect a leaf the conditions need to be right--humid and warm spring. I do not think it will cause too much of a problem. And may not show up in future years.
