Del. Code tit. 3, § 1309

The Department shall have the authority to make reciprocal agreements with the responsible officials of other states. Nursery stock or plants from any other state may be sold or delivered in this State under the same conditions required for sale, delivery, or distribution of Delaware nursery stock or plant materials. An official directory of certified nurseries and related nursery businesses must be accepted from other states in lieu of individual nursery licenses or certificates.