אסור לאכול חדש מתבואת חמשת המינים עד שיקרב העומר שהוא בט"ז בניסן שנאמ' ולחם וקלי וכרמל לא תאכלו עד עצם היום הזה והאידנא דליכא עומר אסור כל יום ט"ז ובח"ל שעושין ב' ימים אסור כל יום י"ז עד תחלת ליל י"ח:

It is forbidden to eat new (crop) of the five types of grain until the Omer is brought, which is the 16th of Nissan. As it says, “And bread, toasted grain, and unripe (or damp) grain you may not eat until (the end of) this very day.” And in these times that there is no Omer, it is forbidden (on) all of the 16th day. And outside of Israel where we observe two days, it is forbidden (on) all of the 17th day, until the beginning of the night of the 18th.

The prohibition of (eating) new (grain) is practiced both in Israel and outside Israel, whether of a Jew’s (grain) or a non-Jew’s.

Grain that did not take root before the 16th of Nissan is forbidden until the next Omer comes. Rama: And nevertheless, all indeterminate grain is permitted after Passover because of a double doubt. Perhaps it comes from the previous year. And even if you’ll say that it came from this year, nevertheless, perhaps it took root before the Omer (Tur quoting the Rosh). And in types of grain that they certainly plant after Pesach, for example in some countries where they plant spelt and barley after Passover, then he should be stringent after the harvest, unless the gates of the country are not closed and most of the grain comes from another place where they plant before Passover. (Hg”M Ch. 11 from the M”A Tos. End of Ch. 1 of Kiddushin) And also, in a time when the winter season extends to after Passover, and in all of that region they plant the abovementioned crops after Passover, one should be stringent and suspect unless known otherwise. But one should not teach others in a place where most of their drinking and eating is from these species, because it is better that they be negligent and not to be pre-meditated. (So it seems in the Tur quoting the Rosh and T”H Ch. 158)