The threat to chlorothalonil, better known as Bravo, is coming to a head in the EU. We have known for some time that it was up for re-registration in October of this year and it was generally accepted that the new terms and conditions were likely to differ from the current ones. The big question is by how much?
As we move into September, thoughts transfer to next year’s planting and that ongoing hope for the elusive combination of high yield and good prices. Hope springs eternal but a threat to chlorothalonil would seriously dent our long-term ability to cope with nature’s survival capacity and our ability to contain resistance development in some plant diseases.
Real concerns
It seems that there are a number of concerns with regard to the re-registration of chlorothalonil. There are reports of issues with carcinogenicity and risks with ground water. There are other issues also but most actives have some issues.
There are also concerns at the producers’ end. For Irish wheat and barley growers, chlorothalonil has been the single most important fungicide active against septoria and ramularia, diseases that have become notorious for developing resistance against mainstream fungicides.
Septoria tritici has become less sensitive to many fungicide families over recent years.
It seems that there are relatively few voices echoing these concerns. Loss of this particular active could seriously threaten our ability to grow successful winter wheat and spring barley. Control of septoria has been a serious issue for more than two decades and most actives did not retain their activity against ramularia for much more than three years.
The strobilurins promised so much in terms of a new highly active family but their promise was short-lived after septoria developed full-blooded resistance.
More recently, we have witnessed the gradual appearance of septoria isolates that show reduced sensitivity to SDHI actives. This is the last family of fungicide actives currently available that shows strong efficacy against septoria.
A product for Ireland
It is important to say that this product is far more significant for Ireland and the UK than anywhere else in the EU. This makes the threat to re-registration even greater. With a growing acceptance that a balanced multi-enterprise agriculture is important for the health of any industry, where are our champions for the retention of chlorothalonil?
The importance of chlorothalonil for grain yield and quality is shown annually in trials from Teagasc, UCD and other research facilities. Chlorothalonil has shown its worth for many decades as a component in wheat and barley fungicide trials. More often than not, it has supported the activity of the main actives and added significantly to yield.
This was most obvious in winter wheat where its presence supported the main actives. Perhaps the only time when it did not show considerable benefit was following the introduction of the strobilurins. These products were so active when they were working that there was little benefit from adding anything else in the tank. But that is history and we once again came to depend heavily on this active.
The other disease of significance is ramularia in barley. This late-season disease has shown incredible capacity to overcome family after family of fungicide actives to develop resistance. The only stable force against this damaging disease has been chlorothalonil.
Without its presence in the market, ramularia would leave a serious dent in both yield and quality of both winter and spring barley on this island. Its removal would be a real threat to malting barley production.
There is little doubt but that chlorothalonil plays a role in the control of many other diseases, albeit a smaller one.
Its greatest benefit in Ireland has been its resilience against those diseases that have been most active at developing resistance.
Resistance management
While we can clearly see almost annual proof of the yield and quality benefits from chlorothalonil in fungicide trials, its impact as an anti-resistance agent is far less clear. The frequent use of this active alongside triazoles, strobilurins or SDHIs is bound to have helped to some degree in preventing or slowing the buildup of isolates that were less well controlled by the main actives.
Ramularia has become resistant to most families of fungicides.
One thing we are certain of though is that when the triazoles weakened against septoria and ramularia, we depended much more heavily on chlorothalonil to do a bigger job, especially following the collapse of the strobilurins.
At this point, we hope to see at least two new fungicide families on the market in the near future. But when they do arrive, how can we protect a new single-site active against resistance development? What might its expected lifespan be against resistance development in the absence of chlorothalonil?
In a high-disease pressure country like this, such products might only have a life expectancy of two to four years without appropriate backup.
Needs a champion
The potential to lose chlorothalonil is great and it might be described as just another loss on top of the hundreds gone before it.
But chlorothalonil is much bigger than most others – it has been the basis for the ongoing efficacy of many other fungicide actives and without it our future in grain production would be challenged.
But where is the urgency of this situation being expressed at political level? Chlorothalonil’s forte is in wet climates against wet season diseases. It is for this reason that it is so important in Ireland and the UK but it is of little relevance on broad-acre crops in most other areas of the EU. So we have very few allies in this battle for retention but who is making the case for Ireland?
The chlorothalonil issue has not been included in press releases from ministers, political parties or other lobby groups. We know there is an amount of work going on in the background but who is the champion for Bravo?
As we move into the final phase for the re-registration of chlorothalonil, it is increasingly obvious that it is under severe threat.Chlorothalonil has been a key component in fungicide mixes on wheat and barley in this country for years.The loss of chlorothalonil would be a serious threat to grain production in Ireland and its removal would shorten the lifespan on any new fungicide actives.
The threat to chlorothalonil, better known as Bravo, is coming to a head in the EU. We have known for some time that it was up for re-registration in October of this year and it was generally accepted that the new terms and conditions were likely to differ from the current ones. The big question is by how much?
As we move into September, thoughts transfer to next year’s planting and that ongoing hope for the elusive combination of high yield and good prices. Hope springs eternal but a threat to chlorothalonil would seriously dent our long-term ability to cope with nature’s survival capacity and our ability to contain resistance development in some plant diseases.
Real concerns
It seems that there are a number of concerns with regard to the re-registration of chlorothalonil. There are reports of issues with carcinogenicity and risks with ground water. There are other issues also but most actives have some issues.
There are also concerns at the producers’ end. For Irish wheat and barley growers, chlorothalonil has been the single most important fungicide active against septoria and ramularia, diseases that have become notorious for developing resistance against mainstream fungicides.
Septoria tritici has become less sensitive to many fungicide families over recent years.
It seems that there are relatively few voices echoing these concerns. Loss of this particular active could seriously threaten our ability to grow successful winter wheat and spring barley. Control of septoria has been a serious issue for more than two decades and most actives did not retain their activity against ramularia for much more than three years.
The strobilurins promised so much in terms of a new highly active family but their promise was short-lived after septoria developed full-blooded resistance.
More recently, we have witnessed the gradual appearance of septoria isolates that show reduced sensitivity to SDHI actives. This is the last family of fungicide actives currently available that shows strong efficacy against septoria.
A product for Ireland
It is important to say that this product is far more significant for Ireland and the UK than anywhere else in the EU. This makes the threat to re-registration even greater. With a growing acceptance that a balanced multi-enterprise agriculture is important for the health of any industry, where are our champions for the retention of chlorothalonil?
The importance of chlorothalonil for grain yield and quality is shown annually in trials from Teagasc, UCD and other research facilities. Chlorothalonil has shown its worth for many decades as a component in wheat and barley fungicide trials. More often than not, it has supported the activity of the main actives and added significantly to yield.
This was most obvious in winter wheat where its presence supported the main actives. Perhaps the only time when it did not show considerable benefit was following the introduction of the strobilurins. These products were so active when they were working that there was little benefit from adding anything else in the tank. But that is history and we once again came to depend heavily on this active.
The other disease of significance is ramularia in barley. This late-season disease has shown incredible capacity to overcome family after family of fungicide actives to develop resistance. The only stable force against this damaging disease has been chlorothalonil.
Without its presence in the market, ramularia would leave a serious dent in both yield and quality of both winter and spring barley on this island. Its removal would be a real threat to malting barley production.
There is little doubt but that chlorothalonil plays a role in the control of many other diseases, albeit a smaller one.
Its greatest benefit in Ireland has been its resilience against those diseases that have been most active at developing resistance.
Resistance management
While we can clearly see almost annual proof of the yield and quality benefits from chlorothalonil in fungicide trials, its impact as an anti-resistance agent is far less clear. The frequent use of this active alongside triazoles, strobilurins or SDHIs is bound to have helped to some degree in preventing or slowing the buildup of isolates that were less well controlled by the main actives.
Ramularia has become resistant to most families of fungicides.
One thing we are certain of though is that when the triazoles weakened against septoria and ramularia, we depended much more heavily on chlorothalonil to do a bigger job, especially following the collapse of the strobilurins.
At this point, we hope to see at least two new fungicide families on the market in the near future. But when they do arrive, how can we protect a new single-site active against resistance development? What might its expected lifespan be against resistance development in the absence of chlorothalonil?
In a high-disease pressure country like this, such products might only have a life expectancy of two to four years without appropriate backup.
Needs a champion
The potential to lose chlorothalonil is great and it might be described as just another loss on top of the hundreds gone before it.
But chlorothalonil is much bigger than most others – it has been the basis for the ongoing efficacy of many other fungicide actives and without it our future in grain production would be challenged.
But where is the urgency of this situation being expressed at political level? Chlorothalonil’s forte is in wet climates against wet season diseases. It is for this reason that it is so important in Ireland and the UK but it is of little relevance on broad-acre crops in most other areas of the EU. So we have very few allies in this battle for retention but who is making the case for Ireland?
The chlorothalonil issue has not been included in press releases from ministers, political parties or other lobby groups. We know there is an amount of work going on in the background but who is the champion for Bravo?
As we move into the final phase for the re-registration of chlorothalonil, it is increasingly obvious that it is under severe threat.Chlorothalonil has been a key component in fungicide mixes on wheat and barley in this country for years.The loss of chlorothalonil would be a serious threat to grain production in Ireland and its removal would shorten the lifespan on any new fungicide actives. 
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