Yarra Valley growers switch away from old chemistry

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The first botrytis fungicide release in decades has been welcomed by grape growers in the Yarra Valley of Victoria as an excellent alternative to existing disease control options that are losing effectiveness.

Viticulturist Adrian Utter, from Muirs, said he had seen the performance of Verpixo® Adavelt® active fungicide in the lead-up to commercial release and was keen to recommend it to his wine grape growers.

Adrian Utter, of Muirs, in the Yarra Valley, introduced Verpixo into wine grape programs last season to control botrytis & powdery mildew.

“Normally we try to look at a product on a smaller scale in the first year but the fact that we haven't had a new botryticide for almost 20 years, it was pretty easy to switch,” he said. “We have an option that can help us with resistance management. We've been using the same three products for the last two decades and there's a good argument there's some resistance out there.”

“Rotating products to reduce that likelihood of resistance developing is a key component to product choice in the spray program.”

He said Verpixo has the advantage, it can be used at several stages throughout the season.

Having the ability to use it in the program at either flowering or pre-bunch closure, gave us good flexibility.”

“Eighty per cent cap-fall and pre-bunch closure are the most critical times for decent botrytis control. You want to control that latent infection that can get in at flowering, and pre-bunch closure is your last opportunity to get something into the bunch that will be there as the grapes ripen.”

“It is really important to hold that fruit as you get closer to harvest. Once the bunches are closed you've got no hope of getting a product in to slow that spread of botrytis down.”

Mr. Utter said Verpixo also controlled powdery mildew making it an ideal option in a tank mix with other products.

“The fact that it controls powdery mildew reduces the number of products we have to put into the tank. One or two products mixed together is a bit easier. Once you start putting four, possibly five, into the tank, it's a bit harder.”

He said the last season was drier, so botrytis pressure wasn’t as high as the previous three years, although there continued to be issues with powdery mildew.

“Where we ran Verpixo and alternative products in comparative blocks, we saw slightly better powdery mildew control. So that's a positive. It gave me the confidence going forward that Verpixo will be a really good fit for us in the Yarra.”

The Yarra Valley is located north-east of Melbourne and is known for premium, cool climate wines.

“Maintaining clean fruit is essential,” Mr. Utter said. “Powdery mildew and botrytis obviously downgrade the quality of the grapes and the resultant wine so keeping the crop clean is essential. We have to run robust spray programs to keep the fruit disease free.”

He said wine grapes in the Yarra Valley were predominantly Pinot Noir and Chardonnay with some Shiraz, Cabernet and Italian varieties.

“Both Chardonnay and Pinot Noir are fairly susceptible to disease, so keeping the crops clean is a challenge.”

Spray programs throughout the season are based on 7-to-14-day intervals and are driven by weather conditions.

“This year, we've undertaken a project with weather stations in the Yarra Valley and software to predict disease severity and outbreaks,” Mr. Utter said. “It probably confirmed our gut feeling as to what we should be doing, but it is nice to see it backed by a bit of science.”

He said the introduction of Verpixo provided another mode of action and took the pressure off the products they were currently using for botrytis and powdery mildew control.

“If we can prolong the life of the other products and keep resistance out, we are going to end up with cleaner fruit in the long run. Having another alternative does preserve the life of all the chemistry. It’s been 20 years since we last got a decent botryticide in the system. It takes a long time to develop these products so the longer we can keep them working effectively, the better it is for everyone.”

Mr. Utter said good spray coverage was also important with the majority of growers in the Yarra Valley quite good at applying products.

“The choice of product is just part of the picture. You've got to get it to the right spot at the right concentration, and you have to get your timing right,” he said.