Responsa for Bava Batra 312:5

בשלמא כרכום חזי אלא קוצים למאי חזי אמר רבי חנינא מאי טעמא דר' אליעזר שכן בערביא מקיימין קוצים בשדות לגמליהן

replied to him, '[Is there any] proof from there? The Meronite was in good health'!<span class="x" onmousemove="('comment',' Had he been in a dying condition his verbal Instruction alone would have been sufficient. ');">¹³</span> HE REPLIED TO THEM: [AS TO] THE SONS OF ROKEL, MAY THEIR MOTHER BURY THEM! Why did he curse them? — Rab Judah said in the name of Samuel: They allowed thistles to grow in [their] vineyard; and R. Eliezer [is thereby consistent] with his view. For we learnt: If [a person] allows thistles to grow in a vineyard he [thereby], R. Eliezer says, causes [the fruit] to be forbidden;<span class="x" onmousemove="('comment',' It is forbidden to grow in the same vineyard heterogeneous plants even though one is used for human, and the other only for animal consumption. ');">¹⁴</span> and the Sages say: one does not cause [the fruit of a vineyard] to be forbidden unless [he grows] a plant the like of which [people] usually allow to grow.<span class="x" onmousemove="('comment',' I.e., plants for human consumption or use. Thistles are mere weeds and as a rule are not allowed to grow among the vines, V. Kil. v, 8. ');">¹⁵</span>

Teshuvot Maharam