Tackling young vine decline

Melanie Weckert digs up grapevine root samples for the young vine decline study.
Melanie Weckert digs up grapevine root samples for the young vine decline study.

Death or decline of young grapevines is a problem for many wine-grape growers in southern NSW.

The National Wine and Grape Industry Centre (NWGIC) ‘young vine decline complex’ vine health team is working to solve this problem.

Wagga Wagga NWGIC plant pathologist, Melanie Weckert, surveyed 500 NSW wine-grape growers in the Riverina around Griffith and found many concerned about declining or failing young vines in their vineyards.

"The young vine decline complex appears to be a sporadic problem of grapevines in this region," she said.

"The symptoms include reduced vigour, weak and stunted shoot growth and a serious decline in yield.

"Cross sections of the trunks show brown to black discolouration."

One grower told Ms Weckert that patches of their chardonnay had lost around three per cent of its vines to sudden death, which equates to an income loss of $7224 a year and a replacement cost of $10,320.

"It appears that too many growers are losing money constantly," she said.

"The vines are extremely slow growing in the early years, and then they often have to be removed and replaced after a few years resulting in considerable costs and loss of revenue."

Ms Weckert said the cause of the disease in the Riverina was yet to be identified, although similar symptoms in countries such as Portugal are known to be associated with vine root ‘black-foot’ fungi (Cylindrocarpon spp.) and the ‘black goo’ or Petri disease fungi (Phaeomoniella chlamydospora and Phaeoacremonium spp.).

These, plus the ‘Bot’ fungi (Botryosphaeria), are also routinely isolated from the declining young vines in the Riverina.

The origin of these fungi is still a mystery.

Do they come from the soil, the planting material or are they transmitted through the air?

Ms Weckert said it seemed that environmental stresses such as frosts, parasitic nematodes and dry conditions play an important role, too.

She said disease management options such as using fungicides, biocontrol agents, and cultural practices were largely unknown.

"During the next four years, the NWGIC will be tackling this mystery so that growers in the future can have greater confidence in the success of their new plantings," Ms Weckert said.