1) The Rambam (Hilchos Bechoros 1:4) and Shulchan Aruch (Yoreh Deah 306:1) write that it is a Mitzvah to make holy the firstborn of a pure animal and say, "This is Kadosh." This is the opinion of the Rabanan in Arachin (end of 29a), who disagree with Rebbi Yishamel who maintains that it is not necessary to say that it is holy.

2) Concerning Bikurim, the first fruits that grow in Eretz Yisrael from the seven species specifically, the Mishnah in Bikurim (3:1) tells us that a person goes down to his field, sees a fig, cluster of grapes, or pomegranate that is the first fruit of the field, ties a string around them to indicate that they are the Bikurim, and says, "These are Bikurim."

3) As far as I know, the Mitzvah of Bikurim differs from the Mitzvah of Bechor of an animal. The Bechor of an animal is automatically consecrated from the womb of its mother, even according to Rabanan who say that there is a Mitzvah to verbally declare it Kadosh. This Mitzvah is only l'Chatchilah; if one did not say anything, it is still Kadosh, as the Rambam and Shulchan Aruch write explicitly. In contrast, the Rambam (Hilchos Bikurim 2:19) writes that Bikurim become Kadosh only if one says that they should. I understood that the difference is that while it is obvious which one is the firstborn animal, it is not obvious which are the first fruits, and it is the owner of the field who has to declare which grew first.

Kol Tuv,

Dovid Bloom

1) I found sources that teach that Bikurim are not holy unless the owner explicitly says they should be.

In the first Mishnah of the third chapter of Bikurim, which I cited above, the opinion of Rebbi Shimon is mentioned. Rebbi Shimon maintains that even though he said that they are Bikurim when they are attached to the ground, he must say again that they are Bikurim after they are plucked from the ground. The Talmud Yerushalmi states immediately that according to Rebbi Shimon, if the owner did not declare that they are Bikurim after they have been plucked, the Bikurim do not become holy. This suggests that according to the Rabanan as well, if one did not declare them as Bikurim when they were in the ground, they also do not become Kadosh, because the dispute between Rabanan and Rebbi Shimon only concerns whether one needs to say they are Kadosh after they have been plucked, or whether one can say it before they were plucked. There is no indication that there is a dispute about whether they become Kadosh without saying anything.

2) In Sefer Toras ha'Aretz 1:71, Rav Moshe Klires (the Rav of Tiberias between 1909 and 1933) cites the Rambam in Hilchos Bikurim 2:14, who says that one who buys plucked fruit together with the land may bring the Bikurim to the Beis ha'Mikdash. The Toras ha'Aretz points out that the Rambam does not say that it is necessary that the owner knows that these fruits were the first of the field to became ripe. This suggests that everything depends on the owner of the fruits declaring them as Kadosh.

3) I found also that the Rogatchover Gaon, in Tzafnas Pane'ach (Hilchos Nedarim 1:10-11), writes that Bikurim possess a "Geder Kedushas Peh," a "definition of becoming holy through what one's mouth says." He compares this to what Tosfos (Nidah 6b, DH d'Afreshinhu) refers to in a different context, to Kedushas Peh. I do not think that the Rogatchover would have referred to Kedushas Peh in connection with Bechor, because we saw in my first reply that the Rambam and Shulchan Aruch write that it is only a Mitzvah l'Chatchilah to say that Bechor is holy, but even if one did not say it is Kadosh it is automatically Kadosh from the womb.

Chanukah Same'ach,

Dovid Bloom