[If] his field was planted with caraway or arum, he may not plant over them, since they do not produce for three years. Grain in which there arose aftergrowth of isatis, and similarly a place of threshing floors in which there arose many kinds, and similarly fenugreek which gave rise to varieties of plants — we do not obligate him to weed. If he weeded or cut down, we say to him: ‘‘Uproot the whole except for one kind.’’