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Fluazinam insensitivity EU-37

This is a reprint of a press released by Wageningen University​, and translated into English:

June 28, 2017

Results from Wageningen University & Research shows that all P. infestans EU-37 isolates tested, displayed a reduced sensitivity to fluazinam. There is a strong indication that the rise of EU-37 in Europe is not only caused by its better fitness but also by a selection advantage in situations in which fluazinam is used.

EuroBlight annually monitors and reports upon the development of Phytophthora genotypes in Europe. The results of 2016, which in many countries was a serious late blight year, showed that two relatively new genotypes are on the rise. Their survival and spread at a time when other clones have failed to establish suggests they are evolutionarily fit and may pose challenges to disease control. One of these genotypes is EU-37.


A single sample of EU-37 was first detected in the Netherlands in 2013 and was sampled locally at a low frequency in the following two seasons. However, it comprised 5.5% of the EU-population sampled in 2016, having spread as widely as England, Germany, Belgium, the Netherlands and NW France.

So far it was assumed that EU-37 could establish due to its fitness. Current results indicate that other characteristics also contribute to the increase of this genotype.

Results from Wageningen University & Research shows that all P. infestans EU-37 isolates tested, displayed a reduced sensitivity to fluazinam. The isolates tested originate from the Netherlands and Germany. They were obtained from fields with a clear reduced efficacy of fluazinam or from potato stores with unexpectedly high tuber blight infection levels. Further research has to establish whether all EU-37 isolates display excellent fitness and reduced sensitivity to fluazinam.

Strategy to reduce risks

To avoid reduced efficacy of fluazinam in commercial potato production, it is important to follow resistance management recommendations: reduce the selection pressure exerted by fluazinam by limiting the number of applications with fluazinam-containing products and alternate with other active ingredients. Also the use of products in which fluazinam is combined with other active ingredients lowers the selection pressure. Implementing the resistance management recommendations could possibly, besides preventing problems with a disappointing efficacy, also prevent the further rise of EU-37 (Dark Green 37).

Our Reaction

While I may not need to remind you of the requirement to employ a range of blight treatments in order to maximise the efficacy of your programme, I would like to take this opportunity to en courage you to send in your blight samples to our Fight Against Blight service.

How to send a sample

We no longer require text messages into the service. This function has been disabled.

You can now submit your reports in five easy steps:

  • Take a picture of the affected area
  • Upload the image to
  • Fill out the relevant report fields
  • Take a note of your report ID number
  • Submit

Sampling protocol:

The sampling protocol for late blight requiries only four sub-samples. For an infection across a field or in volunteer potatoes, samples should be taken from four distinct areas within the field. A single hot spot or outgrade pile still requires four sub samples, even though the infection source is relatively small. This is to identify any genetic variation within the infection.

Results for all positive samples are available on-line at and as always the identification details are anonymous and only known to the scout that sent in the sample.

Genotype analysis on first FAB sample

Analysis at The James Hutton Institute has shown the first FAB sample from Kent in April was caused by genotype 6_A1.  The group will endeavour to provide an early indication of the genotypes causing infections in any blight samples submitted in the coming weeks to support the industry’s management decisions

EU_37_A2 equates to 2.7% of FAB samples tested in 2016 (2 leaf samples & 6 tuber samples post-harvest) – Population data below

Your sample helps everyone fight against blight

By working together we can increase the performance of our blight programmes. News such as the above serves as a reminder of the importance of sharing samples so that we can track insensitivity and resistance across various strains. If you require assistance with our service, please drop me a line.

Regards, Claire

E: | T: 0131 297 7462

Source: Unknown

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