Issue link: http://read.dmtmag.com/i/369547
w w w. v w m m e d i a . c o m S e p t - O c t 2 014 | V I N E YA R D & W I N E RY M A N A G E M E N T 6 7 The chances of pinpointing the virus infection in a specific vineyard will depend on the grower collect- ing the right type and number of samples, as well as the laboratory applying the best testing methodol- ogy of detection. If a grower tests a vineyard due to the presence of suspicious symptoms, the sam- pling will be done by collecting portions of vines displaying symp- toms. Generally, if similar disease symptoms are present throughout the vineyard, fewer samples are required for virus detection. However, if the symptoms are diverse, multiple samples repre- senting different symptoms may be required. It is recommended to work with a knowledgeable plant patholo- gist who can suggest the type of tests and samples to collect to deter- mine the disease-causing agent. If the results show no evidence of infection, the pathologist may rec- ommend increasing the number of samples or testing for other disease- causing agents such as fungi and bacteria, which may cause similar symptoms in the vineyard. SAMPLING FOR PRODUCTION OF CLEAN PLANTING STOCK When the purpose of testing is the production of clean planting stock, a larger number of samples will be required for laboratory test- ing. Mother vines may have been selected initially due to a "healthy appearance" and consequently no symptoms are present in the vine- yard block. While vines can appear + Clonal grapevine propaga- tion can severely impact the health of a vineyard. + Choosing the correct sample for virus diagnostics is essential to obtaining reliable results in the labo- ratory. + In theory, 100% assurance that the planting material is virus-free requires 100% testing. + Plan ahead to develop a testing plan that fits the vineyard's budget and qual- ity goals. AT A GLANCE In this highly infected vineyard, every vine displays virus-specific symptoms. The collection of samples from one or two vines will suffice to determine the cause of disease at the laboratory.