In the grips of what’s been described as a bad powdery mildew season for many growers, a new fungicide from Syngenta, applied early in the crop to help
keep the disease firmly under control is what some are terming a no-brainer.
Compared to a myriad of other powdery mildew products, a single application of Seeker Duo fungicide is the best, as one agronomist explained, for establishing this early disease protection.
In one Western Australian trial (Figure 1) Seeker Duo fungicide kept powdery mildew to just 3.5 per cent incidence observed on the bunches, compared to 16 per cent incidence with a commonly used competitor product.
In the untreated area, there was 96 per cent disease incidence, meaning there was high pressure in the vineyard.
Leading agronomists in South Australia observed the benefits of Seeker under extreme conditions late last year in chardonnay vines at the Syngenta
Learning Centre in the Barossa Valley. Here, Seeker outperformed other commonly used fungicides, when used once at different times in a sulphur-based spray program.
Senior agronomist at Platinum Ag, Virginia Paul Pezzaniti said implementation of only one Seeker Duo spray up to EL 12 (5-leaf stage) made such a huge difference for control of powdery mildew – it’s the best I have ever seen.
He was so impressed with the outcome of the trial he already plans to make Seeker a part of his programs.
“Where one spray (of Seeker Duo fungicide) was used following Thiovit Jet fungicide at the start of the season, this was better than most intensive programs. The site is notorious for powdery and has taken us three years to understand the pressure from the area and [chardonnay] variety.
“We’ll definitely be using Seeker Duo in the spray program next season,” Mr Pezzanti said.
Syngenta technical services lead Dr Brandy Rawnsley expects Seeker Duo fungicide to have relevance to wine grape growers and advisors across Australia, given powdery mildew is one of the key diseases that infects grapes in all viticultural regions.
“You’d be hard pressed to find a grape grower that does not apply fungicides in a spray program for powdery mildew control,” Dr Rawnsley said.
“With so many products on the market, growers need products that work, and work well.
“The arrival of Seeker Duo provides advisors greater peace of mind thanks to its robust, residual control for up to 21 days, while being highly rainfast.
“Coming from the same makers of Miravis, Switch and Thiovit Jet advisors and growers can also have confidence in the rigour in which Seeker has been brought to market.”
Seeker Duo fungicide contains two active ingredients: 375 g/L fenpropidin newly registered in Australia, and 100 g/L difenoconazole.
Proven difenoconazole, a Group 3 fungicide, or better known as a DMI (demethylation inhibitor), has excellent preventative and curative activity. It works by stopping sterol production in the fungus which is required for cell membrane and function.
Fenpropidin belongs to the Group 5 amines (morpholines) and also stops sterol synthesis in fungal membranes at a different site to Group 3 fungicides. It is considered low risk of fungicide resistance development with no known cross-resistance to other chemistry groups.
Dr Rawnsley said the combination of these two actives creates true synergistic activity to enhance efficacy, which is a real benefit to users. When compared to a solo difenoconazole fungicide, Seeker truly provides better control of powdery mildew.
Seeker Duo fungicide can be applied once per season at 40 mL/ 100 L within a protectant fungicide program.
Residue data shows there are no quantifiable residues (<0.01 mg/kg) in wine following one application no later than 80 per cent capfall (EL 25).
When using Seeker Duo fungicide, the vineyard can be entered once the spray is dried offering growers the flexibility of continuing critical vineyard practices.
Formulated as an emulsifiable concentrate (EC), Seeker Duo has a built-in adjuvant, is easy to mix and is compatible with a range of crop protection products across a wide range of grape varieties.
A recent replicated trial in South Australia showed physical and biological compatibility with 20 different tank mixes, with excellent powdery mildew control with each mixture compared to an untreated control.
Seeker Duo has rapid systemic mobility through the xylem to protect developing shoots as they are growing.
“Powdery mildew can arise from infected buds leading to flag shoots,” Dr Rawnsley said.
“Flag shoots are new emerging shoots that can be completely covered in powdery mildew, so it’s critical that fungicides are used early to stop disease development.
“Seeker Duo is one of only a few fungicides that has excellent early curative activity.
“Used preventatively from 3-5 leaf stage protects the vineyard and sets the grower up for a successful season. The results from trials have been remarkable, especially at high pressure sites.”
With only one application per season allowable, the trial showed how to best use Seeker Duo.
Syngenta product lead Scott Matthew explained.
“Start a program with two Thiovit Jet applications from budburst then use Seeker Duo as your first non-sulphur fungicide to protect the developing shoots.
With up to 21-day control, it fits perfectly with Miravis applied pre-flowering which offers excellent protection of the vines at those critical times”.
Director of Stirling Viticulture Trent Reilly agreed.
“I was a bit sceptical about ‘another’ powdery mildew product, but having seen it, it’s the best you can get,” he said.
“Timing is critical; at the right time, at the right grape phenology, I’ve seen that using Seeker Duo gives excellent disease control.
“Seeker fits nice and early in the spray program, it’s a no brainer.
“Another positive is the re-entry of Seeker as it fits into the work program such as checking irrigation and other vine-related activities. I can’t wait to put it in spray programs next season.”
Seeker Duo will be available for the 2024/2025 growing season.
