Produce from EretzYisroel, such as fruits and vegetables, for exampleYaffa oranges, which are bought in a local market is a problem. It can be considered Sofek Tevel, as it is questionable whether the Trumois and Maasrois were actually separated from them. In the year of Shmitah or the year following that of Shmitah, there can be an additional problem associated with the observance of Shmitah. One should not buy such fruits and vegetables without a proper Hechsher. After the fact, if one has bought such fruits, there is a specific procedure in order to properly separate Trumois and Maasrois. These procedures are printed in some of the Siddurim and popular Halachic guides. They include 1) separating a percentage from the fruit, 2) redeeming the Trumois and Maasrois on a Prutah, a coin worth approximately five cents, and 3) then discarding both the separated fruit and the Prutah. For details on how to do this, please refer to your local popular Halachic guide.