Tosefta for Sheviit 2:12

When do we burn [alt., "How long do we wait until we burn," see the GR"A] the dried-up residue (=קשין, lit. "hard stuff," or straw) that is in the fields? As to the fields of fruit-trees, until Shavuot. As to "white" fields (i.e., grain fields, see Sheviit 2:1), until Rosh Hashanah (alt., "Pesach," per Vienna manuscript). As to an irrigated field, [we burn the residue] immediately, the words of Rabbi Yehudah. But the Sages say, as to a white field, until Shavuot, as to a field of fruit-trees, until Rosh Hashanah, due to the robbery of men and cattle [?], and as to an irrigated field, immediately.