Is it forbidden to cultivate fennel containing large quantities of chemical pesticides that farmers avoid eating in their homes, given that these pesticides are available in the market and known to the responsible authorities?

There is no objection to cultivating this crop with the use of authorized pesticides within the permissible limits. However, it is not permissible to use unauthorized substances that are proven to be harmful, nor to use authorized substances in a concentration exceeding the permissible limit, which would result in harm. This is based on the Prophet's (peace and blessings be upon him) saying: "There shall be no harm or reciprocating harm." One should consult experts to ascertain what is authorized and the permissible quantity.