particles growing along the surface of trees

[walterlee]

I tried to animate particles growing along the surface of trees. Mainly used the “find target” operator to make. But there are some problems. First of all, only some particles will find the target, while the other part seems to be blocked by something. Moreover, the "control by time" option in the “find target” operator  does not work properly. Using time control will make the particles unable to bind to the tree surface.
This is my test file, thank you.


https://drive.google.com/file/d/1pLouSw0...sp=sharing