Q.Cherry tree
The leaves of our cherry tree are curling on the sides, lengthwise, and don’t look healthy. The are 2 or 3 branches that have new growth with healthy leaves, but the tree on the whole does not seem well. Fruit this year was poor. Although the weather has been very hot, the ground is moist as we have a sprinkler system.
Please advise on the best treatment.
Thanks,
Robin

Certified GKH Gardening Expert
Curled or rolled leaves can be a sign of insect infestation or disease in cherry trees. Underwatering can also be a cause- do make sure the rtee is receiving enough volume of water from the sprinkler system. This article has more information:
http://homeorchard.ucanr.edu/The_Big_Picture/Irrigation/
Aphids and leafrollers can cause rolled leaves. In this case you would see the insects themselves on or inside the leaves.
A fungal disease caused by Taphrina deformans causes curled and puckered leaves with a distinctive look. Here is more information:
https://extension.psu.edu/plants/tree-fruit/diseases/stone-fruit-diseases/peach-leaf-curl