You will loose effectiveness and it could damage your spraying equipment over time.
Talstar P cannot be used on anything edible, fruits or vegetables. We do however have many products that are labeled for gardens and fruit bearing trees. One of our most popular is our Malathion 55% Spray.
There is no real reason to mix both Talstar and Cyper. They kill pretty much the same insects. One or the other would most likely do the job.
The best general pest control can depend on what region you are located in. One of the all time favorite general pest control products is Talstar P. Talstar has a long residual, so it keeps on killing pests for over three months after you've sprayed it. Plus, Talstar One is odorless, dries clear, leaves no stains, is non-irritating to the skin, and won't break down easily with rainfall. Also for roaches, you want to use a bait like Maxforce Impact, Up in areas you are not spraying Talstar. Please see the roach bait placement guide, as well.