If the inspection shows the presence of dangerously injurious insects or such as are likely to become so, the department shall require the nurseryman to destroy the infested stock and to treat that exposed to infestation in the manner necessary to render the insects harmless and the stock safe.

After complying with the requirements of the department, any nurseryman may apply for a reinspection of his stock, and the department shall, if it finds the conditions fulfilled and the stock apparently clean, issue a certificate to that effect upon such conditions as may be deemed necessary for the protection of purchasers. Such conditions shall be in writing and must be accepted by the nurseryman in writing.