How does sampling work?
Sampling of leaves from Prunus trees in commercial orchards and homeowner
properties in New York for testing of Plum pox virus (PPV) is handled by
NYSDAM and USDA-APHIS, respectively. Surveys are most tightly centered
on and around locations where positive trees have been found the previous
year. Within 1 mile of a site that tested positive, all trees have one
sample taken (8 leaves per tree). Out to 5 miles from former sites of infection,
every tree is sampled at 4 leaves per tree, two trees per sample. Beyond
5 miles, all the orchards are sampled and each orchard has 25% of the trees
sampled at 4 leaves per tree.
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| Trees sampled for Plum pox virus are tagged with a barcode label. |
Each sample consists of eight leaves taken from multiple locations on a tree, as distribution of PPV in infected trees is not uniform. This strategy increases the probability that the virus will be detected if present.
Leaf samples are placed in plastic bags, barcode labeled, and stored on ice until shipped to the PPV Lab at NYSAES in Geneva. Once orchard and homeowner samples are delivered to the PPV Lab, they are scanned into a database and tracked by their barcode number. No information other than the barcode is available to NYSAES. In other words, the PPV Lab performs blind tests with no information on orchard location and history, as well as owner’s name.