Grapegrowers have a win with vineyard weed control

Grapegrowers across different regions are lauding a new herbicide option that promises to be a game-changer for their weed control management into the future.

Some growers are praising the ability to apply the pre-emergent herbicide after budburst, while others are looking forward to resting commonly used herbicides and reducing application passes in their vineyards.

The long-acting Alion^® pre-emergent grass and broadleaf weed herbicide can be used in vine and tree crops and has a 14-day harvest withholding period.

Developed by Bayer, the Group 29 (formerly Group O) broad-spectrum herbicide contains the active ingredient, indaziflam, and it provides pre-emergent weed control for up to 10 months.

At Taylorville, near Waikerie in South Australia’s Riverland region, Phillip Smith grows an equal balance of red and white winegrape varieties for Treasury Wine Estates and Vinarchy with his brother and son.

Phillip said cobbler’s peg had become a problem weed in the vineyard and was particularly hard to control once it was out of the ground, while other weeds to combat included fleabane, thistles, caltrop and innocent weed.

He said they had previously used the pre-emergent herbicide, Stomp, however this had proved difficult due to its requirement to be applied prior to budburst, which also coincided with a busy time in the vineyard.

Knockdown herbicides including Basta, SpraySeed and Roundup also have been used, however they have had to manage these applications carefully according to the time of year and weather conditions in the region.

The Smiths are in their third season of expanding applications of Alion herbicide in their vineyard, and this year they swept debris from under vines in an effort to extend its length of weed control.

“(With our contract with Vinarchy) we can use Alion up to 90 days before harvest, so probably up to early October with early varieties, which is an absolute game-changer because with other (pre-emergent herbicides) you have to use them before budburst,” Phillip said.

“You can incorporate it with your knockdown herbicides and as we have got micro sprinklers, you just give it 10 millimetres of water afterwards to water it into the ground and you are set.”

The Smiths have used Alion with Roundup before budburst and with SpraySeed at E-L 10-11 growth stage, applied with about 300 litres per hectare of water in a 1-metre wide strip either side of vines.

“Last year we used it where we didn’t clean under vines and it still gave us 10 months of control. This year, by sweeping under the vines, we hope to get 12 months, which then means no more passes with SpraySeed and Roundup, it will save us plenty of money in diesel, and it will look very good with our Sustainable Winegrowing Australia (certification),” Phillip said.

“We are always looking at ways to improve our sustainability, which is all good for the environment. We can save diesel by doing less passes, applying less knockdown herbicides is better for the environment, and it all adds up to saving money. And, especially with the industry in a tight position at the moment, any saving is a good saving.

“We are all trying to look after the environment and I think Alion will be a big part of that because it’s applied once a year, and, hopefully after that, you don’t have to worry for another 12 months.”

He said where Alion had not been used in the vineyard, they had applied SpraySeed three times during the growing season followed by Roundup in winter.

“There is resistance to some of the herbicides we use, so Alion will help to give other herbicides a rest. You definitely need to rotate your chemistry, otherwise resistance can be a problem.”

“With Alion, we are now confident we can keep most of our weeds under control, particularly by doing a larger area this year – and, in time, we may do the whole property with it. Being able to mix it with several knockdown herbicides will be very valuable going forward.”

In the Adelaide Hills at Woodside, Tim Wicks grows Chardonnay, Pinot Noir, Shiraz, Riesling, Pinot Gris and Sauvignon Blanc varieties over the family’s 40-hectare Wicks Estate Wines vineyard and consistently contends with wireweed, annual ryegrass and other annual weeds.

Weed control is a strong focus both for vineyard hygiene and frost management. The Wicks’ spray quite wide under their vines to ensure the area can remain free of weeds and generate as much heat as possible to help mitigate frost.

Roundup and Basta herbicides have typically been used against the weeds, with Firepower included in tank mixes with Roundup due to some reduced sensitivity to the herbicide, particularly within the annual ryegrass population.

Tim said herbicide application timing can be impacted by the prevailing weather conditions in the Adelaide Hills and they needed to limit the number of passes in the vineyard.

He said this was why Alion appealed to them, to achieve continuous control of the weed bank under the vines, and, thereby, reduce herbicide applications and vineyard passes.

“We have found Alion can easily be applied with other herbicides, so we can do two things at once, and, in time, we hope it can get us out of using chemicals like Roundup and Basta,” Tim said.

They first applied Alion in early spring, prior to budburst and before a rainfall event of 5-10 mm to incorporate the herbicide.

“In the first year, we applied it at 150 mL/ha with 350 L/ha of water and Roundup. In the second year, we halved the Alion rate to 75 mL/ha with 350 L/ha of water, and we really looked at the vineyard and wondered whether we even needed to apply the Roundup,” Tim said.

“What amazed us was that we used Alion in 95 per cent of the vineyard, and we had a young block where we didn’t use it and the difference was chalk and cheese. We could see the wireweed regenerating within a month where Alion was not applied, whereas the block where it was applied was spotless.

“It was Alion and Roundup compared with straight Roundup and Firepower for any resistant weeds, and we had to do second rounds where Alion was not applied. Wireweed was running rampant and we used Basta to remove the weeds.”

He said there was a reduced application of Basta in the first year of applying Alion, so it saved the cost of the chemical plus operational time and effort.

“In the second year, Basta will only be used on the untreated block and by year three, our goal is we won’t be needing a Roundup or Basta.”

“We certainly see Alion as a chance to rest the common use of Roundup and Basta in the vineyard, so it gives us a handy tool and we are really impressed with the results so far,” Tim said.