Q: I have bermuda in the front yard and Geo zoysia in the backyard. Is there any issue mowing both and risking cross-contamination with their seed? 

A: If the front yard is common seed-producing bermudagrass, not a hybrid sodded bermuda, you might get some spots where it grows in the zoysia. But you are in luck if you have sodded bermuda because sodded bermuda does not produce seeds. Geo is a zoysia cultivar that doesn’t produce many seeds. For these reasons, I would not worry too much about cross-contamination of the two.