I haver noticed that [AFFILIATE='1, nofollow=true, newwindow=true, title="Kubota"']Kubota[/AFFILIATE] filters are made in various places including China. I presume made to [AFFILIATE='1, nofollow=true, newwindow=true, title="Kubota"']Kubota[/AFFILIATE] specs. I know the air filters are made by Donaldson as well as the filter housings. Chinese stuff always scares me because without proper oversight, it can be sub standard.
I Wouldn't worry to much about China filters since you have a Kubota anyways the engines are Chinese made Japanese design. About half of the tractors sold in the US are Japanese design American assembled with Chinese parts to save costs. The other half are either assembled in Japan China or probably Mexico all under supervision of the Japanese. And I know from experience Kubota is very very strict on what goes on their engines or what they go into. I used to be a R&D manager for a machine company that used Kubota engines in them and they did a whole battery of tests on the motors in our applications before we got the application approval. And every one of the engines we got shipped from China had Chinese filters and never had an issue with them even after cutting into them after cycle tests.