Question
I have a non-bearing mulberry tree approximately 18-20 years old.  This year the leaves have developed brown spots all over and they are falling off. Last year in the fall the leaves turned yellow with a few brown spots. It is now fall in Cottonwood AZ and the weather is cooling. I have been advised by the people at Home Depot to spray the tree with Bayer Advanced 3-1 Insect Disease & Mite Control. Is Fall or Spring a better time to spray the tree?

Answer
Dear Ray, This is one of those times that I really get irritated with Home Depot.  The reason is that they don't know what is causing your problem, so they suggest spraying with a product containing NEEM.  Don't get me wrong, I love NEEM products, as it is an organic product that kills mites, fungus, and insects, but there are cheaper NEEM products (just look for NEEM in the active ingredients list#, and I would definitely not spray falling leaves with NEEM.  It just won't do any good, because the leaves are already dying and falling off.  On top of that, spraying a fruitless mulberry will use a great deal of spray for minimal effect at best. Here is what I would do.  Your tree has some type of unspecified fungus, perhaps a Cercospora, perhaps not.  At any rate, the leaves are falling now, so your best bet is to rake up and dispose of these leaves as soon as possible.  This will take some time to rake up, because they have a lot of leaves.  Don't mulch these leaves, just get rid of them, because at this point they are your main source of fungus.  Be sure to check your entire yard for dead leaves and other landscape trash and do a really good job this year cleaning your yard.  Look for any broken limbs on the tree and prune them up, etc.  Then when your tree begins to leaf out next year, keep on the lookout for any spots developing.  If you do see spots then spray with any NEEM product or you could use a harsher product containing fungicide like Proprioconozole and spray with that - which is what I would use on this type of fungus.  However, I am betting that you just had a wetter than average year and it caused the fungus.  You very well may not have any spots after cleaning up your yard.  One other word of note: these fruitless mulberry trees don't often live for a long time, and your tree is getting on in years for this type of tree.  So if you continue to have a lot of problems, it may be nearing time to cut it down and start over with a new landscape tree.  When trees develop spots near the end of their time on the tree, it doesn't really mean that something is wrong, you just have some opportunistic bugs and fungus getting a last snack in before winter.  I would only be really concerned if I see recurrence of this problem in the spring after a good clean up and even then the problem is mostly cosmetic #although it is pretty unsightly on big trees) and won't cause any major problems with this tree.  I hope this information helps, but feel free to write back with any questions you may have.  Good luck, Melissa