Monday, March 23, 2015

Virus Testing Results

DJ's have just completed a round of virus testing for one of our clients considering top working on their Chardonnay vineyard this year. 

Taking a virus test before top-working is a recommended procedure because of the effects viruses can have on the grafting process.




Notes on this virus report



At the date of virus sampling the Chardonnay block tested positive to:
  
LR1: Leaf Roll associated Virus type 1.

LR9: Leaf Roll associated Virus type 2.

LR5: Leaf Roll associated Virus type 5.

RSPaV: Rupestris stem pitting associated virus.  

This is a very common virus with upwards of 60% of all Australian vinifera (wine) grapevines testing positive. This virus is not considered to cause issues with top grafting.

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.

GFkV-A: Grapevine Fleck Virus variant A

Named after leaf appearance on vitis Rupestris; most vitis Vinifera clones and varieties are symptomless. Infection can be caused through grafting incompatibilities. No direct losses in vigour and yield are noted, but in combination with other viruses, shoot strength and yield may be reduced. This virus is located in the phloem. Transmission occurs through grafting and propagation. No field spread has been detected in Australia. 


Unfortunately as this vineyard has tested positive to five different viruses 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