Once again, I suspect regional differences. Here if we say 'crop' in the singular here, it refers to one specific food (usually food that is, it could be cotton, flax, etc.) item and on very rare occasions a mixed field. We use the plural, crops, to indicate more than one type.
Note: I didn't say that gardeners didn't use the word crop, but that it would be modified.
I'm going to have a good bean crop. is an example.
I could also say:
I'm going to have a good bean harvest.
The government discussing weather patterns and the effects on big farm production might say:
The climate this year won't affect the crops. <-- Note the use of the plural. The singular wouldn't be used in this context. They (the government) would
never use the word harvest, and neither do my farming relatives. They are thinking almost exclusively of monetary profits - for someone. Religious organizations would use the word 'harvest' in such a sentence but in the context of discussing hunger, food distribution, people's well-being etc. Not in the context of profits, selling, and buying.
Those with small farms may indeed interchange the use of harvest and crop more freely here. They also grow a greater variety of crops and tend to serve a more local community where they know many of their buyers and the people who eat their food.
Another slight difference <-- Crops are often, though not always, raised with the idea of selling and profits. Harvest does not have this association.
Please note the text in blue. The words crop or crops are not always used in the light of profits and selling; however, here the word
harvest is not used when the focus of the discussion is commerce, profits, and the selling of crops.
Orange Blossom