If your wife's trust is a true Grantor Trust, as defined under Sections 671 through 679 of the Internal Revenue Code (26 USC §§ 671- 679), is administered by a Wells Fargo office in California, and she is a full-year Oregon resident, then then "conditional" answer to your question is no, she does not have to file a California state tax return just to report the income from this Trust.
The "conditional" part of this conclusion is if the Trust receives income from an operating California business interest, or from California rental real estate or royalty property. In that instance, she would need to file a California state tax return, to report such California-source income. In the absence of any of that, however, she does not need to file a tax return in California -- although as a full-year Oregon resident, her Grantor Trust income will be taxable by Oregon, and she should take steps to ensure that an Oregon Form 41 is filed for the Trust (even though no Oregon taxes will be due with Form 41). This same advice stands for filing a Form 1041 (i.e., there is a requirement to separately report Grantor Trust activity, but the actual taxes for any income therefrom is reported on the personal income tax return of the Grantor.
For California state filing purposes however, the fact that the fiduciary (investment advisor) may be located there is immaterial as to the determination of the need to file a California tax return. You can read the following California Franchise Tax Board webpage for additional details:
https://www.ftb.ca.gov/Archive/Professionals/Taxnews/2007/0307/0307_3.shtml
Thank you for asking this important question.
