I assume you mean bacterial wilt. If so, then the only way to protect your plants from it is to not let cucumber beetles munch on your plants. You must kill every cucumber beetle you see because the beetles are what carry and transmit the wilt. You might be able to protect your plants if you cover them with either floating row cover or with tulle. However, you'd have to take it off to allow bees in to pollinate which could also let in the beetles or you'd have to hand pollinate yourself. Also, I believe that the County Fair variety of cucumber is resistant to bacterial wilt (haven't grown it though).

Several years ago there used to be a very interesting discussion about homemade cucumber beetle traps on this forum but for some reason it's not on gardenweb anymore. So traps might be something to look into.

In my own experience, I have found that I don't have a beetle problem if I grow cukes on a bi-yearly basis. If I grow cukes for two years or more in a row, I have a major problem.

Rodney