Field Assay for Identification of Palmer Amaranth from Single Seeds, Seed Mixtures, and Leaves

Amaranthus is a genus of between 60-70 annual or short-lived perennial plants and include many classifications. Some amaranth species are cultivated as leaf vegetables, pseudocereals, and ornamental plants. Unfortunately, some amaranth species are extremely invasive and are classified as noxious weeds, such as Palmer amaranth. This weed poses a serious economic threat to crops such as corn and soybeans and is classified as a prohibited noxious weed in multiple Midwestern states. 

Thus, several states that are experiencing large crop loss due to Palmer amaranth require certified Palmer amaranth-free seed to be able to grow any amaranth type. Seed producers and sellers must test their seeds and seed mixtures to prove there is no threat of such an invasive weed in them, as all of the Amaranthus genus have very similar, small black seeds and it is impossible to visually distinguish the species. Typical testing involves growing a sample of seeds to show plant identification, which is slow and unreliable. Other testing offered includes testing individual seeds using DNA sequencing, which is expensive and burdensome. There is a need for a highly sensitive, specific field assay for the detection of Palmer amaranth seeds in a mixture of other Amaranthus seeds and debris.