What Is This On Leaves?

Thomas_J.

What that is, is Black Spot.
Ch. Elms are prone to black spot in the Spring. It is the new growth that is susepticle to the fungus. Once the new growth has hardened there is nothing to worry about. Until then though, you need to keep water off the new leaves at all cost. If you know that rain is coming, put them somewhere until the wet weather passes. This may sound extreme, but believe me, black spot is very bad for ch. elms. The disease spreads rapidly from the leaves to the branches, where in time you will lose the tree if you don't stop it from spreading. If after a month since the disease has been stopped and you don't see too much new growth coming back, your tree will probably stay pretty much that way for the rest of the year then. Next spring will bring the tree back as if nothing ever happened. At this time you will want to do preventive care on it by doing what I stated about not letting the new leaves get wet, and giving it a drenching or two of the fungicide. What I use for blk. spot is Daconil. I'm not sure if that is scale on your branches since the shot is really close up. If it is scale, and there is too many to scrape off with your finger, I would recommend this: pour a solution of 1 to 2 tablespoon dishwashing detergent, 1 tablespoon of vegetable oil into a plastic gallon and slowly add water to fill the gallon jug. I fill this solution from the gallon bottle into a spray bottle and just before using I add 1 to 2 two caps full (from the rubbing alcohol bottle) of rubbing alcohol and spray immediately. Try to spray mainly on the branches since the oil may affect the leaves abillity to transpire. This solution really worked for me. I know for sure you have blk. spot so Iwould treat it for that first. Better hurry because it doesn't take long for it to get in the branches and cause them to wilt up also. Hope this helps.

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Thomas J.