5. As regards any arable land which is the subject of an agreement and which is suitable for the creation of conservation headlands—
(1) the farmer shall not apply fungicides or insecticides, except between 31st August in any year and 1st January in the following year;
(2) the farmer shall apply herbicides to the land only as agreed in advance with the Secretary of State except that this requirement shall not apply when applying herbicides to that part of the land which comprises a strip of land one metre wide and which adjoins a cropped area.