According to an email received today from Agri-Analysis LLC, the incidence rate of RBaV positive vines is lower than a year ago. Lab Manager Alan Wei and Plant Pathologist and Virologist Tefera Mekuria reported:
In response to clients inquiries of what percentage of samples are positive for red blotch, we have analyzed the data of all samples we tested during the first three months of 2014 and compared with that of Q1 2013. We are pleased to share some information on the incidence rate of RB positive vines. In reviewing these data, please bear in mind that these samples came from various locations and diverse sources including nursery materials as well as field cuttings. Also during Q1, the vast majority of samples were dormant materials without any symptoms that were primarily destined for new planting for the 2014 or 2015 season.
Key findings are as follows:
•The average RB positive rate was 23% in Q1 of 2013 and 15% in Q1 this year.
•The RB positive rate was 20% in January and 10% in March of this year.
•Almost 100% samples includes RB testing.
•The distribution of RB in these samples was highly non-uniform. Some groups of samples were completely clean and some were completely infected.
Combating the red blotch virus has been a truly community wide effort. We encourage growers to continue to be vigilant in screening for RBaV and LR3 - two of the most economically important grapevine viruses.
For an in-depth article on Red Blotch, see the March 2013 issue of WBM