There are a number of different viruses that affect potato plant health and tuber quality. The Diagnostic Lab performs virus testing for certification, diagnosis and strain identification for national surveys. The lab can also perform GMO testing to ensure market access for growers.
The Diagnostic Lab conducts potato virus testing in support of the potato certification program. During the winter post-harvest test, potato virus Y (PVY) is tested in latent virus carrier varieties such as Russet Norkotah, Shepody, and Silverton. Also, during the summer virus test, PVX, PVY, and PVYn tests are offered for potatoes in order for growers to meet certification requirements. Latent virus carrier varieties are required to be PVY tested. The lab provides potato virus testing for potato inspectors during the inspection season and also participates in national potato virus surveys. For immediate in-field testing of suspect plants, program inspectors utilize PVY ImmunoStrips.
Virus testing in potato is conducted using an ELISA test to detect the presence of a specific virus. The department currently conducts virus tests for potato virus A, potato virus M, potato virus S, potato virus X, potato virus Y, potato virus Y-necrotic, potato leaf roll virus, tomato spotted wilt virus, and potato latent virus. Typically, customers are required to submit samples of at least 410 leaflets for most virus tests. 400 leaflets are then placed into 40 test wells, each containing 10 leaflets and tested for PVY, PVX, and/or PVYn. The number of positive wells per total wells tested and a percentage of the disease are reported. Potato sprouts can also be tested for virus at an additional charge.
The Diagnostic Lab conducts tests to detect the presence of genetically modified organisms (GMOs) in potato to support the potato certification program and as a service to potato growers who need to verify their crop is GMO free to satisfy grower contracts. This test is typically conducted during the summer virus test or the winter post-harvest test.
An ELISA test is used to detect the presence of the Bt-Cry3a protein found in transgenic potatoes containing the Bt gene. Customers must submit samples of at least 410 leaflets for this test, as the sample size tested is 400 leaflets. This test can be performed on the same sample as a potato virus test. Samples are composited 40 leaflets per well for a total of 10 test wells. Results are given as the number of positive test wells per total test wells. Also, leaflet tissue is the preferred and least expensive tissue type to test. Potato sprouts may also be tested for Bt-Cry3a for an additional price. For potato sprouts, a 400 tuber sample is required. In this case, samples are composites of 2 sprouts or tubers per well for a total of 200 test wells.