Virus Testing Results
DJ's have just completed a round of virus testing for one of our clients investigating poor vineyard performance.
Taking a virus test before top-working is a recommended procedure because of the effects viruses can have on the grafting process.
At the date of virus sampling the vineyards tested positive to:
LR4-9: Leaf Roll associated Virus types.
GVA: Grapevine Vitivirus A.
This virus has been associated with Kober Stem Grooving and Corky Bark diseases. These diseases are responsible for graft incompatibility, delayed budburst, severe decline, and even death of vines. GVA is generally transmitted by grafting; not transmitted by contact between plants. GVA is commonly seen with pits and grooves around the grafting union.
Unfortunately as this vineyard has tested positive to GVA virus and is considered not suitable for top working.
Please follow this link to the Virus Atlas for more pictures and grapevine virus information - http://ucanr.org/sites/intvit/files/24513.pdf