Potato Testing & Certification

Our potato minitubers and the plants that produce them are rigorously tested at levels higher than those required. The Colorado Potato Certification Service performs all disease testing and inspections.

Below is the current testing and inspection protocol that we follow:

• Laboratory (“clone bank”) material is tested annually for the following:

Potato viruses A, M, M-Idaho, S, X, Y ,
Potato Latent virus (Pot LV, formerly Red LaSoda Virus ),
PLRV (potato leafroll virus),
PSTV (potato spindle tuber viroid),
Clavibacter michiganensis subsp. sepedonicus ( Cms – bacterial ring rot),
Erwinia carotovora subspp. atroseptica and carotovora ( Erw – Black leg).

Testing is done at the 100% level – each plant that will be propagated during the year is tested prior to increase within the lab.

• Greenhouse material undergoes the following:

First visual inspection by the Potato Certification Service. This is done early, usually in the first third of the crop cycle. Inspectors look for correct varietal identification based on vine and leaf morphology. Crop uniformity is observed to look for possible variety mix. Overall plant health, disease symptoms, and general greenhouse conditions (sanitation, weeds, insects, etc…) are noted.

Disease testing is done between 1st and 2nd inspections. Leaf samples are tested for PVA, PVM, PVS, PVX, PVY, PLRV, and PSTV. Sampling is done at the 1% level – 1 sample per 100 plants.

Second visual inspection is done late in the crop, generally in the last third of the crop cycle. Varietal identification is confirmed based on tuber morphology. Overall plant and greenhouse conditions are also observed.

• After harvest, 1% of tubers (one tuber per 100 plants) are tested for bacterial ring rot (Cms), black leg (Erw), and late blight (Phytophthora infestans).

Colorado certification for nuclear material stipulates a zero tolerance for all disease testing (i.e., the crop will not be certified with any positive test result). Additionally, rejection of lots can be based on other diseases or conditions that may seriously affect seed quality.