Lacewing on weeping ornamental cherry?
This summer, my weeping ornamental attracted a huge number of what appeared to be lacewing bugs. Leaves began to look Lacey and brown. Now in early fall, I don't see the bugs, just a tree with half the leaves looking dead. After consulting a tree care expert, he suggested a treatment that I want to get a 2nd opinion of. He said that the lacewing are not causing the issue, but rather are attracted to a fungus in the tree itself. He said he could inject the tree with s systemic chemical to kill the fungus, and that it would be effective for 3 years. This is appealing because I don't want to spray topical chemicals that could hurt the birds or water. Does this systemic injectable sound legit?
I am unable to diagnose the tree problem from your digital image. I can confirm that this tree damage has nothing to do with lacewing adults that you are finding. Although, I would be more comfortable making this statement if I could view the insect that you are calling "lacewing bugs."
I do think a second opinion is necessary. I recommend that you contact your local Master Gardener volunteers in your county. They can also help with your plant problems and that is what they are trained to do.
My initial thought at looking at the tree is that there is some sort of watering or irrigation problem and that the tree is showing signs of water stress. Again, the local Master Gardeners should be able to help you with the initial diagnosis and if they can't help you, they will direct you to one of the WSU Plant Clinics staffed with plant pathologists who can confirm the presence of a fungal disease.
Hope this helps!