You cannot really use organic pesticides except pyrethrins on cucumber beetles. Pyrethrins are very toxic to bees and more toxic than other organics to other animals unless you are careful to follow the label precautions.
County Fair is supposedly less susceptible.
Where diseases are concerned you need a susceptible host, a vector, the presence of the pathogen, and the right environment.
Although the cucumber beetle may be a vector, the presence of the beetle alone is not the problem. lThere can be a lot of beetles present but if none of them are carriers then the disease may not appear.
When I have problems with disease, I usually have too small a yard to just rotate plants to another part. I look for resistant cultivars, but sometimes those aren't as good for other reasons. If problems are persistant, I usually rotate in time and I just don't plant susceptible plants for a couple of years to make sure the vector carriers have died off and give the pathogen time to be reduced. It works for problems that are specific to a particular family of plants. It is a lot harder to do with problems like phytopthora and nematodes which won't go away that easily.
Happy gardening in Hawaii. Gardens are where people grow.