Parashath Noah, Laws of Ziziyoth, Page 13-14:
4. (conclusion) [Odh Yosef Hai (1) Nowadays that we do not use techeleth, and all the threads of the zizith are white, we are still able to fulfill the positive commandment of zizith.
(We rule in this matter according to the majority opinion in the Talmudh, that techeleth is not indispensable, and that white threads alone may also be used. Even though there is an opinion (Rezah z'l and the teacher of R. Meir of Rothenburg) which supports the minority view in the Talmudh that, unless ziziyoth contain techeleth, they are not kasher, this is not the dominant ruling, and it need not be taken into consideration.)]
This learning should be in memory of Maran, HaRav HaGaon Ovadia Yosef, ztz'l.