This is a question we get every now and then.
Typically, a customer will contact us asking if his Etrog is still Kosher after the Pitam on his Etrog has fallen off accidentally.
Before I get to the answer, if this happens to you please contact us immediately so that we can get you a replacement as soon as possible.
What is a Pitam?
At the top of the growing Etrog there is a "Pitam". (see Picture)
In Shulchan Aruch, there are various opinions regarding a Pitam that has fallen from the Etrog.
In the case where an Etrog from which the entire "Pitam" was taken and a dimple was formed in it, this makes the Etrog invalid. Since an Etrog should not be missing a part of it.
If however the "Pitam" is cut exactly at the top of the Etrog and no dimple is formed in it, the Rama's opinion is that it is Kosher, but other Halachic authorities are of the opinion that it should not be used, and in fact on the first day of Sukkot one should try not use it and seek another Etrog.
In the case where only part of the Pitam is broken and a little wood remains above the Etrog, the Mogen Avrohom is of the opinion that one can use it, but in fact, it is good to splurge and take another Etrog.
All of the above is in regards to an Etrog that in the way of their creation and the form of their growth they had a Pitam, and only after they were picked from the tree did the Pitam fall off. But many Etrogs do not have a Pitam and grow without one at all while picking them, as the Pitam falls off the Etrog while it is still on a tree, and these Etrogs are considered Kosher and beautiful. In fact many Etrogs that grow in Calabria have their Pitam fall off while still on the tree.
In summary, if the Pitam had fallen off before the Etrog was picked from the tree the Etrog is Kosher however if the Pitam has fallen after it had been picked it may render the Etrog non Kosher.