Identification: Curling leaves on Magnolia

We have noticed in the last month or so that some of the leaves on our magnolia tree have started to curl. This is the first year we have had any problems with an otherwise very healthy tree. It has had two blooms of pink magnolia flowers this year and a third bloom has just started. On the curling leaves there looks like a black/grey sticky substance and there are some small spots on the affected branches. The tree is watered regularly through a sprinkler system. We live in Victoria, BC. Any help is appreciated and advice on what we might do to resolve this problem. We have put in a call to an arborist. What might be causing this? Please see the attached pics.

Thanks.

 

Perhaps your tree has magnolia scale. These insects produce a sticky substance upon which a sooty mold grows. Info:

http://www.thearborsmiths.com/magnolia_scale.html

Your tree has been healthy; it is regularly watered; you have noticed the problem early on and have taken quick action to consult a professional. All good things!

 

Regarding the soap suggested in that link, I would only use some-thing mild on plants such as Ivory liquid or Safers Insecticidal soap. Some dish soaps can burn the plants.