Reference for Kilayim 6:4
הַמַּדְלֶה אֶת הַגֶּפֶן עַל מִקְצָת אִילַן מַאֲכָל, מֻתָּר לְהָבִיא זֶרַע אֶל תַּחַת הַמּוֹתָר. וְאִם הִלֵּךְ הֶחָדָשׁ, יַחֲזִירֶנּוּ. מַעֲשֶׂה שֶׁהָלַךְ רַבִּי יְהוֹשֻׁעַ אֵצֶל רַבִּי יִשְׁמָעֵאל לִכְפַר עָזִיז, וְהֶרְאָהוּ גֶפֶן מֻדְלֶה עַל מִקְצָת תְּאֵנָה. אָמַר לוֹ, מָה אֲנִי לְהָבִיא זֶרַע אֶל תַּחַת הַמּוֹתָר. אָמַר לוֹ, מֻתָּר. וְהֶעֱלָהוּ מִשָּׁם לְבֵית הַמָּגְנִיָּה, וְהֶרְאָהוּ גֶפֶן שֶׁהִיא מֻדְּלֶה עַל מִקְצָת הַקּוֹרָה, וְסַדָּן שֶׁל שִׁקְמָה, וּבוֹ קוֹרוֹת הַרְבֵּה. אָמַר לוֹ, תַּחַת הַקּוֹרָה זוֹ אָסוּר, וְהַשְּׁאָר מֻתָּר:
If one suspends vines over part of a fruit-tree, he may bring [sow] seed under the rest of it. If, [however], new [vine shoots] have spread [over the rest of the area], they must be turned [bent] back [to where they were suspended]. There was an incident that Rabbi Yehoshua went to Rabbi Yishmael to Kefar Aziz, and he [Rabbi Yishmael] showed him a vine that was suspended over part of a fig-tree. He said to him [he asked Rabbi Yehoshua], "May I bring seed under the rest?" He [Rabbi Yehoshua] said to him, "It is permitted," and he took him up to Beit Hamaganya, and he showed him a vine suspended over part of a branch [beam] of a <i>shikmah</i> [a fig tree that grows in the wild] tree, which had many branches. He [Rabbi Yehoshua] said, "Under this [the branch over part of which the vine had been suspended] it is prohibited, and [under] the rest is permitted.