Strict guidelines remain for blight control, new product available

As fungicide products become harder to come by and resistance strains continue to cause problems in potatoes guidelines need to be adhered to.

Siobhán Walsh

26 March 2025

Strict guidelines remain for blight control, new product available

Mild temperatures and high rainfall levels meant high blight pressure on Mark's farm.

As we look ahead to a new season for potatoes, blight remains a challenge as always, except that challenge is becoming more difficult. The new resistant strain, EU43, is now in all potato-growing regions across the country according to Teagasc, and farmers face a technical challenge when deciding on a blight control programme for the season.

As we look ahead to a new season for potatoes, blight remains a challenge as always, except that challenge is becoming more difficult.

The new resistant strain, EU43, is now in all potato-growing regions across the country according to Teagasc, and farmers face a technical challenge when deciding on a blight control programme for the season.

They face huge costs as fungicides need to be applied regularly to keep blight at bay.

However, it is clear that the guidelines on blight control need to be followed, because if blight does develop it will be an even bigger problem for the farmer and add further to costs.

Speaking at an event last week to launch BASF’s new potato fungicide, Teagasc researcher Steven Kildea said the key guidelines remain in place.

You need to mix and alternate modes of action, and think about resistance management throughout the entire programme.

Guidelines for blight control:

Mix different modes of action.

Different fungicide families.

Do not mix CAA and Zorvec.

Cymoxanil is not a sufficient mix partner.

Alternate different modes of action.

Alternate different fungicide families where possible.

Avoid sequencing CAAs (eg Revus) and Zorvec.

Steven explained that you need to be thinking about resistance management throughout the entire programme. There are less products coming through the pipeline and so what is there needs to be minded. That’s where the guidelines come in.

When Teagasc devises the blight control guidelines for the year, Stephen explained that in 2024 the team was missing a product to fill out the plan according to anti-resistance and Fungicide Resistance Action Committee (FRAC) guidelines.

He added that “we need to use all actives, but use wisely and not rely overly on any”.

He explained it is important to equalise out the number of fungicide families in the programme and not to use one too often and to use a rate that will give effective control.

Privest

Paul Gobbard of BASF said Privest is a new fungicide available this season from BASF.

It is a co-formulation with two modes of action. It contains 75g/l ametoctradin and 453g/l potassium phosphate. This means there is a mixture in the can, so no other product is needed at the times it is applied.

Paul explained that it is a truly systemic fungicide that controls all blight strains and has a low resistance risk. It fits well into the early part of the season as it can protect new growth well.

It can be applied three times in the season and of course it should be alternated with another product.

In positive news, another new fungicide is on the way next year pending registration and there is also an insecticide and a herbicide in the pipeline.