Problem with flying grass and flowers

I had a crash after using the foliage tool. Now i have a section like a vertical Plane with some grass types and flowers. I can not select anything.
Any Idee to fix that?

288171-anmerkung-2019-09-23-151310.jpg

Hello,

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Thanks

i have solved the bug. one square on the laandscape was buggy. i repaint the material and now it is ok.