Tosefta על בבא בתרא 283:1

A Gentile (alt., "convert," per Erfurt manuscript) who died and the Jews plundered his property [as he left no heirs (see Bava Batra 142a:3, following Steinsaltz)], it is presumed [that anything still] attached to the ground is liable in everything [i.e., peah, gleanings, forgotten sheaves, and tithes], and that all that is unattached from the ground is exempt from everything. The presumption is that standing grain is exempt from the [laws of] gleanings, from forgotten sheaves, and from peah, and liable in tithes (but see Hagahot HaGR"A, switching "exempt" and "liable" here).