Rain brings disease threat for vineyards, but it’s mostly…

Last week’s rain brought an increased threat of disease in vines across the Clare Valley, but grapegrowers say the moisture will be mostly beneficial leading into the growing season.

Ahead of the rain, downy mildew warnings were issued by the Bureau of Meteorology, and the likelihood of powdery mildew and botrytis are also of concern with the increased moisture.

Platinum Ag Services, Clare, manager Nic Jones, said his staff had already had some reports of downy mildew in local vineyards following last week’s rain and said treatment chemical may be in short supply.

“We’ve heard reports of downy mildew within the region already, and with threats of powdery mildew and botrytis more prevalent now there’s some moisture around, chemical could be tight as other regions of the state have been spraying vineyards for at least the past five weeks,” he said.

“On the plus side, it will provide good soil moisture going into 2019, and vineyards hopefully won’t have to water as much as a result.”

Taylors Wines, Auburn, viticulturist Ben Mitchell, said while he had noticed “a couple of dead oil spots” on vines, downy mildew had not been a major issue yet and was hopeful they were on top of it with a regular spray program.

“We keep a pretty tight spraying schedule of every 10-14 days at this time of the year, so we’re doing as much as we can to prevent disease occurring,” he said.

“All of our oil spots that were there seem to have dried out due to our spray program and hotter weather.

“If we didn’t spray and have a regimented spray schedule, we’d be getting pretty nervous about mildew right now, but with a simple chemical sulphur you can get 10-14 days protection and with DMI (demethylation inhibitors) up to 21 days protection.