| EFFECT OF FUNGICIDE ON FHB PATHOGENS |
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Currently, there is no one fungicide on the market capable of giving 100% control of FHB.
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To date the best control achieved is between 60 and
70%. However to achieve this level of control the fungicide needs to be applied
at the correct time.
- Optimal fungicide timing = five days pre or post inoculum arriving on the ear
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This can be difficult to achieve and as a result fungicides should be used only as part of an integrated management
program.
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As part of a three-year project funded
by the HGCA (Project Report No. 297), several trials have been carried out at
CSL to investigate the effectiveness of fungicides against FHB. Unless otherwise
stated the results presented are from CSL trials.
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The trials were carried out on plots artificially inoculated with a mixed conidial suspension containing
F. culmorum, F. graminearum, F. avenaceum, F. poae and M. nivale vars nivale
and majus. Plot humidity was maintained at a level greater than 70% for five days following inoculation.
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Grain was analysed at the John Innes
Centre for the presence of FHB pathogens using competitive PCR. Results from
trials carried out between 1999 and 2001 are presented.
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| 1999 |
The effect of a range of fungicides applied at full rate was investigated. All fungicides were applied two
days post inoculation.
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Fungicides applied were difenoconazole (as �Plover� at 0.3 l/ha), kresoxim-methyl + epoxiconazole
(as �Landmark� at 1 l/ha), metconazole (as �Caramba� at 1.5 l/ha), carbendazim (as �Derosal WDG� at 400 g/ha),
azoxystrobin (as �Amistar� at 1 l/ha), tebuconazole (as �Folicur� at 1 l/ha) and prochloraz (as �Sportak� at 0.9 l/ha).
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- M. nivale DNA was not found in any of the samples analysed by PCR.
- Significant reductions in the levels of F. culmorum, F. graminearum and F. avenaceum DNA
were seen following applications of tebuconazole, carbendazim, prochloraz or metconazole.
- Azoxystrobin was ineffective against any of the true fusaria.
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| 2000 |
The effects of fungicide rate and fungicide mixtures were investigated. All fungicides were applied
two days post inoculation.
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Fungicides applied were tebuconazole (as �Folicur� at 1 l/ha and 0.5 l/ha), metconazole (as �Caramba� at 1.5 l/ha
and 0.75 l/ha), azoxystrobin (as �Amistar� at 1 l/ha and 0.5 l/ha), kresoxim-methyl + epoxiconazole
(as �Landmark� at1 l/ha), epoxiconazole (as �Opus� at 1 l/ha and 0.5 l/ha), tebuconazole + azoxystrobin
(as �Folicur� and �Amistar� both at 0.5 l/ha), metconazole + azoxystrobin (as �Caramba� and �Amistar� at 0.75 l/ha
and 0.5 l/ha respectively), and epoxiconazole + azoxystrobin (as �Opus� and �Amistar� both at 0.5 l/ha).
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CSL, York
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- The predominant species detected by PCR was F. graminearum. High
levels of F. culmorum and low levels of M. nivale DNA were also
detected.
- Full rate applications were more effective than reduced rate applications.
- Application of a triazole fungicide significantly reduced the levels of
F. culmorum and F. graminearum DNA.
- Application of a triazole fungicide had no effect on the level of M.
nivale DNA detected compared to the untreated control.
- Application of azoxystrobin significantly reduced levels of M. nivale
DNA.
- Of the mixtures both tebuconazole and metconazole mixed with azoxystrobin
significantly reduced the levels of F. culmorum, F. graminearum
and M. nivale DNA detected.
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| Morley Research Centre, Wymondham, Norfolk |
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- The predominant pathogen DNA detected by PCR was M. nivale. Relatively low levels of F. culmorum
and F. graminearum were also detected.
- The application of a triazole reduced levels of F. culmorum and F. graminearum DNA detected.
However no fungicide application gave a significant reduction.
- Where azoxystrobin was applied, either as a straight formulation or as part of a mixture,
levels of M. nivale DNA were significantly reduced.
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| 2001 |
The effect of fungicide rate and application timing on FHB pathogens was investigated. Fungicides were
applied to plots either 2 days pre-inoculation (S1) or 2 days post-inoculation (S2). Levels of inoculum used
to artificially infect the plots were reduced compared to previous years in order to achieve disease levels
comparable to a natural infection.
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Fungicides applied were tebuconazole (as 'Folicur' at 0.5 l/ha and 0.25 l/ha),
azoxystrobin (as 'Amistar' at 0.5 l/ha and 0.25 l/ha) and tebuconazole + azoxystrobin
(as 'Folicur' and 'Amistar' both at 0.5 l/ha and 0.25 l/ha).
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- F. culmorum was the predominant pathogen. No M. nivale
DNA was found in any of the samples.
- All fungicide treatments, with the exception of the post-inoculation azoxystrobin
(0.25 l/ha) treatment, significantly reduced the level F. culmorum
DNA compared to the control plots.
- Fungicide treatment did not significantly affect any other Fusarium
species.
- Levels of FHB pathogen DNA were much lower than in previous years. Reducing the level of inoculum
applied to the ear reduced the differences in fungicide efficacy seen in previous years.
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