I wrote about this in the context of the Royal Navy recently here.

To give you a brief tl;dr, Scurvy only became a problem when ships started taking long journey's without the ability to resupply, such as a transatlantic crossing. The British only started serious research into preventing scurvy in the 18th century. This was because their navy was needed in many far away theatres and they had a shortage of manpower for their ever growing navy, thus they needed to keep the men they had alive.

I recommend you check out the answer I linked above as I go into more depth there, and have provided all the material necessary to understand the topic fully, in the context of the Royal Navy at least.