Moed Kattan 3a - Toldos by Shevi'is

The gemara seems to indicate that to be considered an av it must be written in the Torah by shevi'is, that is why plowing is considered a Tolda (even though by shabbos it is an Av). But not every melacha written by shevi'is is an Av. Regarding Zeriah/Zemirah the gemara understands that Zeriah is the Av and Zemirah the Toldah. Regarding Ketzirah/Betzirah the gemara understands that Ketzira is the Av and Betzirah is the Tolda. Rashi is very meduyak in that we determine Zeriah to be the Av because it is more basic, and by default Zemirah is the Tolda. But by Ketzirah and Betzirah, they are both exactly the same just that one is to grapes and the other to tavuah. We cannot figure out from sevara which is the av and which is the Tolda, so we look at shabbos and determine that just as by shabbos Ketzirah is the av, so too here Ketzirah is the Av.

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In short: Zeriah and Ketzirah are Avos. Zemirah and Betzirah are Toldos that you are chayev malkus for. Charishah is according to all an issur D'oraysa (if we assume that R' Elazar is the opinion who says that you don't get malkus - see Tosafos 3b). R' Yochanan would hold that you get malkus by charishah and by all the toldos mentioned in braisa (bec. only acc. to R' Elazar we say the braisa is an Esmachta). R' Elazar holds that Charishah is d'oraysa (based on klal prat..) but no malkus (based on his explanation of R' Dimi), and all other Toldos mentioned in braisa are only D'rabonon.