New York wineries work to stop sour rot

After a frost last year caused vineyards to lose up to 40% of their harvest, farmers are expecting a bigger harvest this year, but not without taking costly measures to prevent further diseases.

Bruce Murray, owner of Boundary Breaks in Lodi, said they are starting to see what their harvest will look like for the season.

“You have berries now, so this is the start of a classic cluster of grapes forming on the vine and this year we have a lot of them. We think it will be a very big crop,” Murray said.

Murray explains what sour rot looks like through photos. (Emily Kenny/Spectrum News 1)

But damaging frost isn’t the only danger growers need to be wary of. The different stages of cultivation bring different types of threats to the grapes and vines, including a fungal disease called sour rot.

“Basically, this happens when the skin becomes very fragile. What is happening here is that the berry is injured or an insect pierces it like fruit flies or wasps. Fruit flies, in particular, not only see the breakage, but they fly around and transmit the bacteria,” Murray said.

The grapes will then start to smell like vinegar, which doesn’t make for good wine, he said. Damage can also occur when it rains a lot and the grapes absorb moisture and split. Many growers are selective about the varieties they plant for this reason.

Employees post informational articles in a freshly planted vineyard. (Emily Kenny/Spectrum News 1)

“First, try planting grape varieties known for having looser clusters,” Murray said.

Managing these conditions can be costly.

“That’s probably between $70,000 and $80,000 a year in spraying for our 50 acres that we manage, and that’s a combination of equipment, personnel, materials and time,” Murray said.

Research into the impacts of sour rot and management strategies conducted by Cornell University found that the presence of fruit flies, wasps and birds has a significant impact on the severity of sour rot.

Bottles of Boundary Breaks wine available in their tasting room. (Emily Kenny/Spectrum News 1)

“It’s the combination of the damage and the flies that really makes the situation worse. If you just have damage without the flies, you might see a little more sour rot depending on the type of damage, but actually when you add the flies you get a powerful effect,” said Greg Loeb, professor of entomology.

He found two different strategies to combat sour rot: using insecticides to suppress the fly population or keeping damage from wasps, flies and birds to a minimum.

But it’s not always that simple.

“Three of the four classes (of insecticides) labeled for use against fruit flies showed high levels of resistance, which doesn’t necessarily mean these chemicals are failing, just that they don’t work as well.” , Loeb said. “This makes it even more difficult for producers.”

Paul Brock, owner of Silver Thread Vineyard in Lodi, grows Pinot Noir, which is particularly susceptible to sour rot, and takes a slightly different approach to managing the disease.

Murray is standing in one of his vineyards. (Emily Kenny/Spectrum News 1)

“If I can give the berries a thicker skin, I feel like they will be more resistant to sour rot,” Brock said.

Instead of reacting to sour rot when it is already present, Brock uses biological materials to combat diseases that activate the plant’s defense mechanisms.

“One of the reactions we’ve seen is thicker skin. The only measurement I really have is on the crushing plate, where I know the fruit I’m growing has a lower yield than the fruit I’m getting from other people, even though I treat it the same way.” , Brock said.

In other words, he sees less juice and more solids when he puts his grapes through the press. In addition to biological influences, it uses calcium sprays known to help thicken the skin.

Murray shows off a brand new bunch of grapes that will continue to grow until they are ready to harvest. (Emily Kenny/Spectrum News 1)

Although Brock has found that this has helped his grapes, he would like to see more research on sour rot and other diseases linked to climate change. With the changes in weather patterns, Brock said we have had warmer nights and higher humidity which contribute to the development of more sour rot.

“I think most of the industry is really focused on traditional sour rot research like ‘give me an antimicrobial, give me an insecticide’ and I say traditional, but it’s really new. Sour rot hasn’t really been a problem until the last 15 years or so,” Brock said.