You don't, instead you must encourage it, something that can be difficult in pesticide ridden cities with few bees. However the details might differ, I still suspect the level of difficulty is about the same. One must not only prevent the wrong fertilization, but provide the correct fertilization in order to grow hybrid seed corn. Legions of "Jutes", are used in this endeavor in many areas.
I grew very nice tomatoes this summer, and all I did was plant and fertilize (once).