It's absolutely true. Japanese farmers created more intensive agriculture on average and had a disproportionate share of production. They were also pioneers for new crops (for instance, the hood river, or cherry industry was Japanese in origin; ditto the berry industry of bainbridge island, wa) and ran very successful wholesale businesses. The Japanese American specialty was rehabilitating farmed out land that had been drained of nutrients and finding profitable ways to restore soil quality. Their success was in spite of the fact that laws made it illegal for Japanese immigrants to own land and purchases were made in the names of their children. Groups like 'the sons of the golden west' had been organizing against Japanese Americans well before internment and used Pearl Harbor as an excuse to push their racist agenda.