Fungicide testing sheds more light on emerging blight strains

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Results of research into the fungicide sensitivity of GB late blight isolates was presented at AHDB Agronomists’ Conference 2018 today (4 December.)

The work – carried out by Dr Alison Lees, a Research Leader at the James Hutton Institute (JHI) – tested fungicides belonging to a range of Fungicide Resistance Action Committee (FRAC) groups for their ability to inhibit late blight.

Dr Lees noted that a limited number of isolates of P. infestans belonging to lineages known to be either established or relatively new to Great Britain were tested. 

Results of testing genotype 37_A2 provided supporting evidence of its resistance to fluazinam, as previously reported.

Dr Cooke, who was presenting the findings from JHI at day one of the Agronomists Conference in Kettering today, said:

“Isolates of genotype 36_A2 were more difficult to inhibit than those of the other genotypes across several active ingredients and appeared to be relatively aggressive. However, the findings do not provide evidence of specific or multiple shifts in resistance.

“Performance using products at field rates will not necessarily be affected. Therefore, recommendations on use for 2018/19 are unchanged.” 

FRAG-UK guidelines on resistance management in potato late blight remain of high importance. It will be important to monitor the situation with regards to the emergence of 36_A2 and other genotypes in the context of their aggressiveness, to test further isolates and to monitor field performance.

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