| EFFECT OF FUNGICIDE ON FHB SYMPTOMS |
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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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Visual assessments were carried out
at GS73 and GS85. The results from the GS85 assessments are shown for 1999 to
2001.
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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 0.3l/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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- All the treatments applied reduced levels of disease compared to the untreated controls
- Greatest reductions were seen with application of tebuconazole, carbendazim, kresoxim-methyl +
epoxiconazole and metconazole.
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| 2000 |
The effects of fungicide rate and fungicide mixtures on FHB 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 0.5l/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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- All fungicide treatments reduced the level of disease compared to the control.
- Tebuconazole and metconazole applied at full rate were the most effective treatments.
- In general, the use of a full rate straight formulation gave greater control than the half rate straight
formulation.
- In general, where a half rate triazole was applied in mixture with a half rate strobilurin the control
achieved was equivalent to that of the half rate triazole used alone.
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| 2001 |
The effect of fungicide rate and application timing on HB symptoms 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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- Disease levels on control plots were much lower than in previous years (5.5
% compared to circa 30 %).
- All fungicide treatments, with the exception of the post-inoculation azoxystrobin (0.25 l/ha) treatment,
significantly reduced the level of disease compared to the control plots. No other significant
differences were seen.
- In general the higher the fungicide application rate the greater the control achieved. No difference in
degree of control of symptoms was seen between the two fungicide application times.
- Reducing the level of inoculum applied to the ear reduced the differences in fungicide efficacy seen in previous years.
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