Goddess Alakshmi is Goddess
Lakshmi’s sister, unline Goddess Lakshmi, Alakshmi is the goddess of misery and bad luck. It is believed that Alakshmi like sour and pungent things, and that makes lemon more useful to attract the goddess.
It is easier to poke pins in lemons
As lemon is quite easy to poke with a pin, it is used for black magic. Insertion of pins is the main thing which actually hurts the person on which one is doing black magic. Partial insertion causes a physical disability and complete insertion causes death, as per the legends.
Lemon has supernatural powers & Easily;y Available
Lemon is said to have supernatural powers and that is why it is chosen as a medium to carry out the magic. Lemons are available almost everywhere, almost every time of the year. Wizards do not need to go on a hunt and hence it is their first choice.
Source: Daily Bhaskar