Section 26G. If an order issued under section twenty-six F is not complied with within the time prescribed or if the trees or parts thereof are not rendered harmless as a source of further infection or infestation by spraying or otherwise the local superintendent shall cause the trees or parts thereof covered by the order to be removed and destroyed and he shall certify in writing to the owner the cost of such removal and destruction. Such cost shall be payable to the city or town within ninety days from the date of said certification, and if not so paid, may be recovered by suit together with costs thereon; provided, however, that, if, as the result of an appeal taken under section twenty-six F, the commissioner determines that suppression measures are necessary for the control of the Dutch elm disease or the beetles which spread said disease, and that the total cost of such suppression measures is in excess of the financial ability of the landowner to pay, the said cost may be apportioned between the owner and the city or town; and provided, further, that the cost payable by such owner shall be not less than one fourth of said total cost and that the cost to the city or town shall be includible in its accounting for the purposes of section sixteen. Any owner who has appealed from the order issued under section twenty-six F and is aggrieved by the certified cost chargeable to him may apply to the board of selectmen in a town or the city council in a city, as the case may be, for abatement thereof, and such abatement may be granted by said board or by said city council, with the approval of the mayor, but such abated cost shall not be includible in the accounting of the said city or town for the purposes of section sixteen.