Gemara

39a: Rav Anan and Rav Chanan saw a man planting wheat and barley in a vineyard in Chutz La'aretz. Rav Anan thought that they should excommunicate him!

Rav Chanan: No, the Halachah follows R. Yoshiya. One transgresses Kil'ai ha'Kerem only if he plants a grape seed and two other species together.

54b (Mishnah - Beis Shamai): One does not add a fifth when redeeming Kerem Revai (fourth year grapes), and it need not be eradicated at the time of Bi'ur;

(Beis Hillel): These laws do apply to it.

Beis Hillel learn a Gezeirah Shavah "Kodesh-Kodesh" from Ma'aser. Just like adding a fifth and Bi'ur apply to Ma'aser, also to Revai. Beis Shamai do not learn the Gezeirah Shavah.

Berachos 35a (Beraisa - R. Akiva): "Kodesh Hilulim la'Shem" teaches that one must bless before and after eating (Revai, fourth-year produce).

Question: "Hilulim" (plural) teaches two laws. We need it to obligate redeeming ("Chilul" is like "Hilul," "Hei" and "Ches" are interchangeable) Revai before eating it (outside Yerushalayim), and that redemption is needed only for what is used for Hilul (praise), i.e. wine!

One Tana holds that Revai applies to fruit of all trees. He does not expound redemption is needed only for wine, so it can teach about blessing. However, this is difficult for the opinion that Revai applies only to a vineyard.

36a: Whenever there is an argument (about things that grow) in Eretz Yisrael, the Halachah in Chutz la'Aretz follows the lenient opinion.

Rishonim

Rambam (Hilchos Ma'achalos Asuros 10:15): It seems to me that Revai does not apply in Chutz la'Aretz. Rather, one may eat fourth year Peros without redemption at all. We learned only that Orlah applies in Chutz la'Aretz. This is a Kal va'Chomer from Surya, in which Ma'aseros and Shemitah apply mid'Rabanan, but Neta Revai does not apply there. All the more so, Revai does not apply in Chutz la'Aretz.

Ran (Kidushin 16a DH u'Revai and Rosh Hashanah 2a DH ul'Inyan): Indeed, if even Kerem Revai does not apply in Surya, all the more so it does not apply in Chutz la'Aretz. The Rambam learned from the Yerushalmi that it does not apply in Surya.

Rebuttal (Rashba Teshuvah 156 attributed to Ramban): In the Yerushalmi, Rav Bivi explains that R. Yehudah learns Revai from Ma'aser Sheni, that it does not apply in Surya. We hold like Beis Hillel, who learn Revai from Ma'aser Sheni, so we should say the same. However, if so Revai should not apply in Shemitah, just like there is no Ma'aser in Shemitah! Beis Hillel say that Revai has Chomesh and Bi'ur, i.e. even in Shemitah! Rather, the Yerushalmi discusses whether we learn all laws of Revai from Ma'aser Sheni. The one who does holds that there is no Revai in Shemitah. Revai applies in years in which there is Ma'aser Oni but no Ma'aser Sheni, for Ma'aser does apply. The other opinion learns from "Kodesh Hilulim" that it applies in Shemitah. R. Zeira rejected this, and said that R. Yehudah exempts Revai only from Chomesh and Bi'ur in Shemitah (but it has Kedushah), and exempts only Peros Nochri in Surya. Beis Hillel obligate Chomesh and Bi'ur. This shows that they learn Revai from Ma'aser only regarding Kedushah, Pidyon, Bi'ur, and being Hash-m's money. We do not learn the time or place it applies. "V'Araltem... Shalosh Shanim; ...uva'Shanah ha'Revi'is" connotes that Revai applies whenever and wherever Orlah does, i.e. even in Chutz la'Aretz. Even though in Chutz la'Aretz we follow the lenient opinion in Eretz Yisrael, R. Zeira holds that in Eretz Yisrael R. Yehudah exempts only Peros Nochri, for he holds that 'Nochrim can acquire land in Eretz Yisrael to exempt from Ma'aser. The Yerushalmi holds like R. Yochanan, who says that Orlah in Chutz la'Aretz is mid'Oraisa, i.e. a tradition from Sinai. Whenever the Halachah is unclear, we follow the custom. In Chutz la'Aretz, people do not treat Revai with Kedushah. One may rely on the Gaon (She'altos) and Tosfos (who say that it applies only to a vineyard).

Rosh (Berachos 6:1 and Ran Kidushin 16a DH u'Revai): Nowadays (Ma'adanei Yom Tov (4) - where we live, in Chutz la'Aretz), Revai applies only to a vineyard, but not to other trees. Since there is an argument about whether Neta Revai applies in Eretz Yisrael, or only Kerem Revai, in Chutz la'Aretz we follow the lenient opinion. Ran (ibid.): Also Tosfos and the Ba'al ha'Ma'or say that Revai applies only to a vineyard.

Rebuttal (R. Yonah Berachos 24b DH ul'Inyan...): The Ri says that there is no Klal (general rule) that whenever there is an argument in Eretz Yisrael, in Chutz la'Aretz we follow the lenient opinion. This was said only about caper fruits. Also, in Chutz la'Aretz, Rav Chanan needed to say that the Halachah follows R. Yoshiya regarding Kil'ayim. It did not suffice to say that there is an argument in Eretz Yisrael, so we follow the lenient opinion in Chutz la'Aretz! Rather, the Klal applies only to Ma'aser and Orlah. Rabbeinu Moshe ha'Zaken says that even Kerem Revai does not apply nowadays, but he did not say to act upon this, for the Ge'onim say that it applies.

Defense #1 (Gra YD 294:28): Also regarding Kil'ayim, we say that in Chutz la'Aretz the Halachah follows the lenient opinion (Shabbos 139a)! Also the Yerushalmi says so. Tosfos (139a DH v'Lishlach) says that the Klal applies when the lenient opinion holds that the species is permitted in Eretz Yisrael.

Defense #2 (Imrei No'am Berachos 35a): The Klal is not so strong. Perhaps we do not rely on it to follow an individual against the majority. Therefore, it was better to say that the Halachah follows R. Yoshiyah (everywhere).

Poskim

Shulchan Aruch (YD 294:7): Neta Revai applies even in Chutz la'Aretz. Some say that it is only in Eretz Yisrael, but in Chutz la'Aretz Peros after the third year are permitted without redemption.

Shach (17): Therefore, one should redeem everything without a Berachah.

Gra (28): The Rambam permits entirely. The Rashba proved that the Yerushalmi permits only Revai of Nochrim in Surya, and Chachamim forbid even of Nochrim there! One opinion in Tosfos (Kidushin 2b DH Esrog) supports the first opinion. He says that even the opinion that learns "Kerem Revai" exempts Neta Revai only mid'Oraisa, but obligates it mid'Rabanan. If so, all obligate Neta Revai in Chutz la'Aretz. However, Tosfos in Rosh Hashanah (14b) and Sukah (39b) disagree with this opinion. The primary opinion is like the Rema (below).

Rema: Some say that Revai applies in Chutz la'Aretz only to grapes, but not to other fruits.