Section 26F. When notice of positive diagnosis is received by a local superintendent affecting elm trees or parts thereof on privately owned land within five hundred feet of public land, he shall so mark said trees or parts thereof with a sign, and shall give written notice in hand or by certified mail of the diagnosis to the owner or person or persons in charge of the land on which such tree or parts thereof is located. Such notice shall contain an order that said owner or person or persons shall cause said tree or parts thereof to be removed and destroyed within thirty days of the date of said notice except that when such notice is received during the months of September, October, November, December, January or February, removal may be delayed, if necessary, until a later date, but not later than March thirty-first next following the receipt of the notice. If the removal and destruction of said trees or parts thereof cannot be accomplished within the time limits herein designated for reasons beyond the control of the owner or person or persons in charge of the land, he or they shall by spraying or otherwise render the said trees or parts thereof harmless as a source of the spread of the Dutch elm disease infection or as a breeding place for the beetles which spread said disease. The person or persons so notified may within ten days after receipt of said notice appeal in writing to the commissioner from the order contained therein requesting a hearing on the order, and said appeal shall stay the order until the appeal has been heard and decided by the commissioner. He may change, modify or confirm the order contained in the notice and his decision shall be final. The decision of the commissioner shall be communicated to the chief superintendent, the local superintendent and the appellant in writing, shall state the decision and the facts on which it is based, and if the original order is not thereby modified or changed, the commissioner shall direct the appellant to carry out the order within the time prescribed or by a later designated date because of the menace of the Dutch elm disease and the seasonal danger of its spread.