Question
QUESTION: The tree is about 10 feet tall, planted professionally between Boone and Blowing Rock (approx 3500ft altitude) 1 year ago.  Has just developed multiple small wart-like growth on leaves.  Appears to be random (not all laves affected, growths about 1-2mm, solid (can see no insect when cut). Local nursery doesn't know what it is.

ANSWER: What you are describing are most likely insect galls.  The bugs may not be inside any more but the gall will remain.  They probably will not harm the tree. If you want to, you could treat the plant with Bayer Advanced Tree and Shrub Insecticide.  This product is mixed with water and poured on the soil around the base of the plant.  It is taken up systemically and will kill the bugs within a week or so.  It also provides protection from reinfestation for up to a year.  I wish you good luck.  Thanks.

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QUESTION: David,

Thanks for the fast reply, answer and rx recommendation..I may not have described accurately as I could have..the "warts" are <0.2mm, top and bottom of leaf 10-20 (approx per leaf, no spotting and no color changes on leaf except beginning die back)..local guy back called and thought was fungus.  I think you are right and wonder only if a more accurate description changes any thing?

Answer
If the warts are all similar in shape but yet each one having a rough appearance, I would say they were insect galls.  If the warts are smooth, you may be dealing with an insect called scale.  The scale will be oval in shape and do not move.  I have seen aphids on river birch many times.  You can check to see if they are aphids by moving them with your finger.  If the squash with liquid inside and are green, then I would say they were aphids.  The best way would be to send me a picture.  You can email a picture to [email protected] with the subject line of allexperts so it wont get deleted.  I can best tell by that method.  Awaiting your response.  Thanks.