Growth or scab on underside of crabapple tree
We have noticed a change to the leaf of a young crapabble planted in our yard last spring. I have attached photo of top and underside of one leaf. We do have issue with insect and fungus control of roses and live about 1/8 mile from lake shoreline. The tree is a lollipop crapabble. Can you identify and recommend treatment? Any help is greatly appreciated.
It is hard to diagnose with 100% certainty from a photo, but it is most likely cedar-apple rust. It is a fungal problem that requires two hosts. In this case a juniper and the crabapple. It doesn't effect the junipers too badly, but may cause early leaf drop on the crabapple. Fungicides can be applied preventatively or the junipers can be removed. At this point the leaves are already falling so good garden clean-up is essential. More information on this rust disease and how to control it can be found at: http://www.ipm.msu.edu/green_industry/landscape/cedar_apple_rust and more at:http://msue.anr.msu.edu/news/cedar_apple_rust_disease_on_junipers