Question
I have a fruitless mulberry tree. The leaves are turning yellow and have brown spots and are falling off the tree.  We live in north Texas and have had plenty of rain this summer.  If I put sulfur around the tree will that help?

Answer
These are leaf spot fungi. I would treat the tree with a fungicide. First rake up any fallen leaves and destroy them this will reduce the amount of spores from the disease that may reinfect the tree. The fungicides that work on leaf spots are:
mancozeb (Fore, Dithane, Mancozeb); chlorothalonil (Daconil*, Bravo, Ortho multipurpose fungicide*); Thiophonate-methyl (Cleary's 3335, Domain) and triadimefon (Bayleton, Strike). Just follow the directions on the label. I would spray weekly for several weeks until the new leaves have no sign of spots. Your local nursery can help select the fungicide that is best.