My father-in-law, Berel Ludmir, was a merchant of etrogim, the citrus fruit that is used (as one of the Four Kinds) during the holiday of Sukkot. There are many detailed laws and customs attached to what kind of etrog one uses and there is even a tradition that many have to use an etrog grown in Calabria, Italy, for there's a tradition that the fruits from the Calabria region are purebred.
Every year, my father-in-law would bring to the Rebbe some exceptionally beautiful etrogim, produce of the Land of Israel.
The Rebbe would always inquire about that year's crop and the quality of the year's fruit. The Rebbe would always offer some advice on the growing of the etrogim.
Once, my father-in-law asked the Rebbe on which etrog he would recite the blessing during the holiday. The Rebbe, who would make the blessing on an etrog specifically brought from Calabria, did not want to in anyway embarrass him by saying that he did not use the one he brought. So the Rebbe avoided responding to the question.
"I understand," my father-in-law said, "that the Rebbe, according to tradition, only uses a Calabria etrog." The Rebbe smiled.
They then discussed the possibility of planting an etrog from Calabria in Israel. The Rebbe gave several suggestions on how to make this possible.
I later learnt that this was indeed done in Kfar Chabad, where there are several "Calabria" etrog orchards.
