61. The Minister may require a certificate holder to submit to the examination referred to in subparagraph 1 of section 54
(1) where the holder’s certificate has been suspended;
(2) where the holder, in performing work involving the use of pesticides or in selling pesticides, has failed to comply with this Act or the regulation;
(3) where the holder seeks the modification of the class or subclass of his certificate or the class of pesticides he is authorized to sell or use;
(4) where he is of opinion that new developments in the field of pesticides require it.