On April 30th, our UPL potato technical lead - Geoff Hailstone - was joined by three experts from across the industry to host a dedicated, hour-long webinar on the subject of potato blight and how to deal with the rising threat of resistant strains.

We heard from:

• Dr. David Cooke - Lead research from the James Hutton Institute, which runs the Fight Against Blight monitoring service

• Eric Anderson - Senior agronomist at Scottish Agronomy

• Stephen Kildea - Plant pathologist and research officer at Teagasc

The webinar kicked off with a question asked directly to all the growers who’d joined to watch live:

The results clearly showed an eagerness to tackle the problem, with cost factors taking a backseat compared with the threat of resistant strains and ineffective control.

Diving into the threat from the continent 

With only an hour to cover several key topics, we got stuck straight into discussing the threat from Europe, with the change in blight strains and the risk of seed imports.

Dr. David Cooke from the James Hutton Institute began by explaining the rise of the EU43 and EU46 strains and their resistance to carboxamide fungicides like Revus.

These strains have caused widespread losses in the Netherlands after abnormally wet conditions overwhelmed fungicide programs over-reliant on this chemistry.

Eric Anderson quantified the potential impact these strains could have here, warning that "a worst case scenario 10% yield loss across the UK potato area would equate to £138 million in lost value.”

Stephen Kildea cautioned that the threat of import via seed shouldn’t be growers' only concern, as these resistant blight strains could easily spread via the wind across to the UK mainland too.

Reducing the levels of inoculum with cultural controls 

Our next section focused on the importance of reducing primary inoculum sources through strict hygiene.

Everyone on the panel emphasised the importance of eliminating volunteers, discard piles, ground keepers and other potential reservoirs.

Steven advised "it's easier to avoid it than try to rescue it later because that can cause more problems."

The Fight Against Blight and forecasting tools

With Dr. David Cooke on the panel, our talk soon turned to discussions of monitoring and forecasting to help growers deal with the blight threat.

He encouraged us all to use the Fight Against Blight programme for population monitoring, as it provides an "early heads up on what's going on with blight populations this year.”

We then moved onto a discussion around decision support tools and their utility.

Eric cautioned that decision support systems can sometimes "underplay the real risk" based on the experience in the Netherlands. He recommends "maintaining a 7-day program and using decision support to indicate when to use more aggressive, anti-sporulant products."

Designing effective spray programmes 

The fourth and final section of our blight webinar focused on the various guidelines from FRAC and manufacturers, and how to understand fungicide groupings to design more effective programmes.

Our panellists outlined strategies to mitigate resistance development through a responsible mix of available modes of action, as well as touching on those key guidelines.

David spoke about "mixing and alternating because that's what's worked in preventing resistance in Denmark,” while Stephen suggested deploying multi-site protectants in robust and alternate mixtures at >80% rates, to help us move away from that reliance on mancozeb and manage resistance.

There was so much discussed, too much to cover in detail.

We shared some key application guidelines to deal with the threat of blight last month, but to get the very best insight and understanding watch the webinar in full.