It is an almost universal custom on the 15th of Shevat, the Rosh Hashana of the trees, to partake of many fruits and to recite many times the bracha of Borei Pri Ha'etz (Mogen Avraham Siman 131). The Bnai Yisocher adds that one should pray on Tu Beshvat that he be privileged to merit a beautiful esrog for Succos. Harav Moshe Wolfson shlita suggests that praying for a beautiful esrog is hinted to in the words the Torah uses to describe an esrog which it calls "Pri Etz Hadar" which has the same numerical value as "borei pri Ha'etz". When one recites the bracha Borei Pri Ha’etz on the fruits on Tu BeShvat, he should concentrate on the words “Borei Pri Ha’Etz” for a ‘Pri Etz Hadar”.