Proper Vineyard Sampling
With the majority of vineyards in California growing older, we are seeing more and more concern with virus. Through the planting booms of the 1980s and 1990s growers and nurseries and did not have virus' on their radar. Everybody was just trying to meet the demand the industry had presented and the technology used for testing was not as good as it is today. With that in mind, we wanted to give our growers some guidance in examining your suspect fields and taking correct samples so the labs can analyze things properly.
Back in 2004 Sunridge started retesting all of our increase blocks. We started with our oldest planted material and at present we have tested all mother blocks that have been planted since 2005. It has been a very expensive process but we feel our clients and the entire industry need to be more pro-active in testing their vineyards. As the largest Grapevine nursery in the state, we wanted to set a good example by leading the industry with an aggressive approach.
The majority of our blocks are planted in approximately 50-100 vine increments. The setup is quite different than production wine grape plantings but with a catalog of hundreds of clonal and rootstock selections, we have a lot of blocks out there. We prefer taking a composite sample of the blocks to get the highest percentage sampled but at the same time keep things somewhat cost effective. At over $750 per sample and with 100 plus samples to test each year, our lab bill adds up quickly. By taking a sample from 5 vines, we can essentially get 5-10% of the block tested.
When taking the sample cuttings, you need to take cuttings from the base of a main spur. The cuttings should be 6"-8" in length. Please see diagram below:
The most important part of testing is timing. We take all of our samples in September early October in the Southern San Joaquin Valley but for the coastal growers a post harvest sampling in late September through early November will yield viable readings. The viruses are most prevalent at this time and you will get the most accurate results.
There are a few labs to use but for our in-house testing we like to send everything directly to Foundation Plant Services at UC Davis. Another option that we occasionally use is Agri-Analysis in Sacramento. Both facilities provide full PCR testing services, by far the most advanced method to test your samples. Please let us know if you need contact information for either of these laboratories.
Hopefully some of this sampling information is helpful to you. If you have anymore questions regarding taking samples please contact your area vineyard representative. We also have all information available on our testing in house if you should want to know the testing history on your current vine order.