Esrogim exported from Eretz Yisroel for Succos 5776 (2015) have kedushas sheviis (sanctity of fruit of the Shmittah year), and must be disposed of in an appropriate manner. There are a couple of ways to accomplish this:
(i) An esrog may be used to make esrog jelly. The remnants of the esrog should be discarded in the manner described below. The esrog jelly must be eaten and not be wasted.
(ii) An esrog may be wrapped in plastic and left to rot, after which it may be discarded. [If it is not wrapped in plastic, it will dry out and will not rot. Furthermore, after rotting, the plastic serves the purpose of covering the esrog, so that it will not come into direct contact with the trash.]
If the esrog has not rotted by the first day of Shevat 5776 (January 11, 2016), there is an obligation of biur at that time. The esrog should be placed in a public area in front of three Jewish male adults, and the owner should announce that he is declaring the esrog to be hefker (ownerless). He (or any Jew) should then take the esrog and dispose of it in the manner described above. It is preferable to send the esrog back to Eretz Yisroel if it is known that biur will take place there.
[TLS]
Is their anyone collecting them to send to Israel ?