My local supermarket carries some Israeli produce like tomatoes, oranges and avocados. I know that the Torah prescribes various laws for crops grown in Israel. Does that apply also to exported produce?
The Aish Rabbi Replies
Yes, it does.
Trumah and Maaser are terms for various tithes that apply to Israeli-grown produce, to be given to the Kohen and Levi. Untithed foods are called Tevel and are not kosher to be eaten. If you're visiting Israel, or even if you're buying Israeli oranges or tomatoes in your local supermarket, you should make sure that proper tithes have been taken from all grains, fruits and vegetables.
The Torah (Leviticus ch. 25) says that every seven years, agricultural work must cease in the Land of Israel. This is called Shmita – the seventh, sabbatical year. Produce that grows on land that was "farmed and worked" during the seventh year is not kosher. Today, with the return of a Jewish agricultural industry to Israel, the laws related to Shmita are once again very relevant. So if you're buying Israeli produce, make sure the laws of Shmita were properly observed.
Here is an article which describes the process for separating Trumah and Maaser from Israeli produce: http://oukosher.org/blog/consumer-kosher/separating-terumah-and-maaser/. (See also comment there regarding Shmita produce, which is relevant in certain years.)