Blight is the bane of potato growing and experts warn that, long-term, pressure in the UK is only set to rise. Together with his business partner at Spud Agronomy, John Sarup, is responsible for over 11,000 acres of potatoes across Northern England up to the Scottish Borders.

“Getting to the source of the inoculum is key,” he says. “Usually that’s about controlling volunteers, and growth on potato dumps. With the loss of CIPC, we’re turning to maleic hydroxide, a sprout suppressant, which is an effective active for controlling volunteers. The next step is understanding which genotypes you’re dealing with. As soon as blight appears in your crop, take a sample and send it in via the ‘Fight against Blight’ initiative. It will help you make informed decisions about what products you can use safely without causing any resistance issues.”

Despite the delayed start to this year’s season, AHDB have already recorded the first incidence of 2021. Several patches of the disease were seen in a crop of Maris Peer in Kent when the sample was collected on May 26.

“You’ve got to look at the strengths and weaknesses of products and use products when they are likely to be most effective. For example, some perform well on tuber blight and are effective at preventing spores dropping onto leaves, systemic products are generally more effective during rapid growth when you’ve new leaves every two or three days, while other products are better at stable canopy because they are purely a protectant.”

With fewer products available and the need to adjust fungicide programs according to weather conditions, growth stage and disease profile, Sarup welcomes new products such as Enervin SC®.

“Growers and agronomists certainly have a challenge when it comes to protecting crops without exceeding maximum applications of a given product, or of an active ingredient dosage,” says Matthew Goodson, specialties market manager at BASF. “It’s why we have developed our latest blight product, Enervin SC®, as a straight formulation; it gives producers flexibility and potentially, simplifies program planning for growers and agronomists.”

Enervin SC® is the first straight formulation of ametoctradin, an active ingredient that sits in the QoSI chemistry group. It’s well suited to the stable canopy slot and potentially frees up CAA and QII chemistry for use elsewhere in the program.

“Eurofins’ trials, are demonstrating Enervin SC®’s efficacy. Working synergistically with a partner product, it consistently provided outstanding control despite the artificially high disease pressure. It worked well in partnership with propamocarb, mandipropamid and mancozeb. In 2020, we repeated the trial replacing mancozeb with a cymoxanil/propamocarb co-formulation. Again, all treatments stood-up to the challenge well,” he says.

BASF has another blight spray in the pipeline, BAS657. It’s a co-formulation, with two unique modes of action in ametoctradin and potassium phosphonate. Positioned early in the program, it offers protection when the crop is at rapid canopy development, protecting the foliage.

“The loss of diquat means we’re flailing crops. We want a quick kill, predominantly to ensure we hit customer specifications but also because that’s when crops are vulnerable to late blight getting in through the damaged haulm. And if the weather is against you, there’s nothing else you can do,” the farmer concluded.