Ireland
April 17, 2009
New research at
Teagasc Crops Research
Centre, Oak Park, Carlow has found that current strategies to
control the wheat disease Septoria tritici may be under threat.
In recent weeks strains of Septoria tritici were found in some
crops that were less sensitive to the fungicide prothioconazole
(Proline) in the laboratory than any previously tested. These
strains also show a reduction in sensitivity to epoxiconazole
(Opus).
Dr Eugene O’ Sullivan, plant pathologist at Teagasc Crops
Research Centre, Oak Park said: “It is not clear if these
changes will affect fungicide performance in the field this year
but fungicides should be used in a way that will reduce
selection pressure. Triazole fungicides should not be used in T0
(pre-T1) sprays. In subsequent sprays, prothioconazole and
epoxiconazole should only be used in pre-formulated mixtures or
tank mixes with partner fungicides with different modes of
action.”
The triazole group of fungicides have been the mainstay of
cereal disease control for three decades. The strobilurins,
popular in the late 1990s and early 2000s quickly succumbed to
developing resistance in 2003. Growers have relied on triazole
fungicides for most of their disease control since then. “We
need to do all that we can to avoid any reduction in the
efficacy of triazole fungicides,” stated Dr O’ Sullivan.
This development is a cause for major concern according to
Professor Jimmy Burke, head of Teagasc’s Crops Research Centre.
He said: “It is not clear how the shift in insensitivity will
affect disease control by prothioconazole in the coming growing
season. Intensive monitoring of the evolving fungicide
sensitivity situation will continue at Oak Park. Teagasc
researchers will monitor developments in the field as the season
progresses, testing the efficacy of the fungicide in crops. In
the meantime, growers must choose fungicide strategies wisely.”
Previous studies by scientists at Oak Park have shown a
reduction in sensitivity of septoria to the triazole fungicides
Folicur and Caramba but not to Opus and Proline. But this has
now changed and growers are warned to be vigilant so that world
class yields can still be attained,” said Professor Burke. |
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