3,541. Nullifying Second Tithe in Mixtures

Hilchos Maaser Sheini and Neta Revai 6:15

If someone plants second tithe produce after it entered Jerusalem, what grows is considered second tithe. If it’s planted before entering Jerusalem, what grows is considered secular produce even if it comes from something whose seeds don’t deteriorate. The second tithe should be redeemed when it’s planted.

Hilchos Maaser Sheini and Neta Revai 6:16

If second tithe produce gets mixed with other things, it is nullified when the other thing represents the majority of the mixture. This is the case regarding second tithe that entered Jerusalem and was then taken out, and the walls of the city subsequently fell. In such a case, it would be impossible to return the produce to Jerusalem, and also impossible to redeem the produce since it had entered the city. This is the rule even when the extra fifth of redemption is less than a prutah. Since it’s something that can’t be rendered permitted, it’s nullified by a majority of the other item, as we discussed in Hilchos Maachalos Assuros.