Speculation – Should Not Bees Have A Balanced Diet?

Since there are a lot different flowers. Could it be that bees actively selects flowers based on a variate of reasons? From an evolutionary perspective I guess that they select flowers based on what helps them and their offspring survive. Like fighting off disease. So I wonder if farming would benefit from a distribution of nearby flowers. Or what flowers you need for the bees to get a balanced diet for a selected type of crop.