(1)  Location. A scion-block shall be located not less than 100 feet from any nonregistered cultivated plant of the Rosaceae family. The ground in a scion-block and for a distance of 20 feet surrounding it shall be kept either clean cultivated or in an approved, properly controlled ground cover. Registered scion-block trees shall be plant and maintained in a manner and at sufficient distance that branches of different varieties do riot overlap. Care shall be taken in the use of pollinizing insects and pollen application to prevent the transmission and spread of virus diseases through the use of infected pollen and/or its application. Registered scion-block trees shall not be used for propagation purposes until trueness-to-name has been established. Each tree shall hear a permanent registration number.

(2)  Acceptability. The rootstock and top-stock sources of the scion-block trees shall have originated from foundation trees established under this program or from virus-tested trees originating through the Inter-regional Project No. 2 (IR-2)  . If the tree is scion-rooted, its source shall have met the above requirements. Only registered trees shall be permitted in the scion-block.