With the advent of the month of Nisan, the Halacha requires recitation of Birkat HaIlanot, (Blessing on the Trees), upon seeing blossoming fruit trees. Ideally, two trees are necessary to warrant reciting the Beracha. This is indicated by the plural form of the word "Ilanot" used in the Beracha. If a person found only one tree, the Poskim discuss whether the Beracha can be recited.
Hacham Ovadia in Hazon Ovadia, in the section dealing specifically with Birkat HaIlanot, cites the Hida (Rav Haim Yosef David Azulai, 1724-1806), who says in Moreh B’Esbah, "those who are "scrupulous" in Misvot recite the Beracha over two trees." Some Poskim infer from his use of the word "scrupulous," that two trees is only an added advantage, but the basic Misva could be performed with only one tree. However, Hacham Ovadia rejects this understanding. He rules, citing the Petah HaDvir, that if there is only one tree, it is a "Safek Berachot," and the Beracha should not be recited.
However, in a later book, Hazon Ovadia, dealing with Hilchot Berachot (pp. 457-458), Hacham Ovadia reaches a different conclusion. There, he rules that if one found only one tree, the Beracha can be recited. In general, the later rulings of Hacham Ovadia supersede his previous ruling, and therefore this ruling to recite the Beracha is the definitive Halacha.
Rav Mazuz also rules that one tree is sufficient. There is also testimony that Rav Shlomo Zalman Orbach and Rav Moshe Feinstein (as stated by his disciple, Rav Ephraim Greenblatt in his Rivivot Ephraim 8:77), as well as the Rosh Yeshiva of Ner Israel would also recite the Beracha over one tree.
SUMMARY
If one found only one blossoming fruit tree, he can recite Birkat HaIlanot.
