New actives are as rare as teeth in a hen this year but there is still a lot of chatter about the new Syngenta SDHI adepidyn. While it may still be a year or more away from the market here, it is worth keeping an eye out for it if you are visiting field trials this year.

The first question that might arise is why would anyone get excited about a new SDHI active when we are seeing decreased sensitivity in mutations of many fungi to other actives from that family.

Well, the answer to that is that it is an SDHI with a difference. It is actually a unique sub-group which claims to bring both mildew and fusarium into its portfolio of susceptible diseases.

Described as a new generation fungicide by Syngenta, the company claims that it will provide better and longer-lasting disease control, initially in both wheat and barley. A clearance on oats is anticipated in time but not initially.

Adepidyn™ is the trademark for the active ingredient pydiflumetofen. It is a new chemical group – N-methoxy-(phenyl-ethyl)-pyrazole-carboxamide – and considered by some to be a next-generation fungicide, due to its unique molecular structure and related properties.

However, it is still a single mode of action and needs to be used sensibly and managed to minimise the risk of resistance development.

The active is already registered in countries across the Americas, Asia and Africa and registration in the EU is currently ongoing, where France is the rapporteur country.


It is expected to be used on many different crops, as well as the cereals we grow in Ireland. These would include maize, potatoes, brassicas, pulses, soya beans, vegetables, peanuts, grapes, tomatoes and fruit crops.

It is also said to offer excellent performance against fusarium head blight

On these crops, it is claimed to be active against many different pathogens which include leaf spots, powdery mildew, botrytis and sclerotinia.

On cereals, it is said to be good against many of our common foliar diseases. This includes the majority of the leaf-spot diseases which would include septoria, rhyncho, net blotch, rusts, mildew and ramularia. It provides both curative and protectant activity against pathogens.

But as well as these, it is also said to offer excellent performance against fusarium head blight. If this proves true it would be the first modern non-triazole active to be affective against Fusarium spp.

Some of the strobilurins were highly active against Microdochium spp but not against fusarium. And if this claim is carried through to Irish fields, it should also help reduce the levels of mycotoxin contamination in cereal seeds.

Syngenta has already done some fusarium specific work on malting barley here in Ireland and results indicate a worthwhile reduction in ear fusarium levels. This could be valuable in all crops for yield protection but is very valuable for the brewing sector where fusarium contributes to a ‘gushing’ problem in beers.

While its primary use will be in cereals, Adepidyn is being evaluated for its ability to control chocolate spot in beans this year.

Irish trials to date confirm that its major strengths are septoria in wheat and net blotch in barley but ramularia control in barley has been outstanding to date.

Syngenta see the flag leaf timing in cereals as its major strength, applied in mixtures with a triazole and also a multisite product.

It is also worth noting that adepidyn will be tested in field beans this year as there are indications that it could be good on chocolate spot and that would be a major benefit.

Rainfastness and longevity

Another of the unique characteristics of this active is its balanced distribution within plant leaves and its outstanding rainfastness.

The active is said to bind quickly and strongly to the wax layer on the leaf surface from which it slowly penetrates into the plant tissue over time.

This then contributes to the even concentration of chemical active in the plant tissue over time, which is also said to add to the longevity of the protection offered against diseases.

A comment coming from some researchers who have worked with the active during its development is that it keeps on performing long after application.

Whether this continues to be the case five years into its commercial life remains to be seen but it is a good place to start.

A leading safety profile

As well as these functional characteristics, it is said to be safer for the consumer, the user and the environment. It claims to have a lower risk profile than most or all of its competitors.

Its low application rate may help in this respect but it is still said to be potent and long-lasting.

Like all other fungicides, it is not to be used on its own and I understand that it will come initially as a co-formulation with prothioconazole and also as a co-pack. As is the case with most new products coming to the market, its use is confined to one application per crop per season.

A long incubation period

While there is still no certainty about when it will be available to EU or Irish growers, it is worth noting that the development of new actives takes a very long time and a lot of money.

It was first synthesised in 2008 and then submitted initially for registration in 2015.

It is understood that the process was delayed because it got caught between two different versions of the registration regulations due to the time when it was submitted. This resulted in a requirement for additional information that had not been previously required for product registration.

Key points

  • Adepidyn is a new fungicide active with a very broad range of disease control ability across many different crop types globally.
  • It is particularly good against virtually all leaf-spot diseases.
  • It is said to have good activity against the fusarium ear blight complex.
  • It will be used initially on wheat and barley, but uses on other crop are expected in time.
  • It is not yet registered in the EU but this is hoped for in time for next season.