The Korean season begins in Jeju Island in the south, which is like the "Hawaii" of Korea. I have seen Jeju blueberries in early May.
US shipped product arrives in June and July.
Here are some photos of fresh blueberries in three markets: We say can safely that the imports have not depressed prices of local production. In fact, Koreans always value locally fresh blueberries produced fruits and vegetables. At same time the imports are giving more and more Koreans an opportunity to enjoy fresh blueberries!