A breakthrough emergency authorisation for Cuprokylt has provided the only fungicide available to organic potato growers for the control of late blight, at a key time of the season.
The Extension of Authorisation for Minor Uses (EAMU) was driven by industry leading stakeholders, including Certis, Agrii, the Agriculture and Horticulture Development Board (AHDB), National Farmers’ Union and several organic growers associations.
The active ingredient copper oxychloride is available to organic potato growers until September 28, 2018.
“Being able to utilise copper oxychloride will support organic growers and help them to capitalise on market demand,” said Nick Winmill, Agrii Potato development manager.
“Without copper, only cultural control methods are available for the control of late blight in organic potatoes, and as a result, it’s been difficult to keep varieties with preferential qualities blight free.
When wet weather hits and if temperatures remain, blight pressure is likely to increase, so this news comes at a crucial time.
Winmill warned that if another extension isn’t secured for copper oxychloride, or if an alternative isn’t found, for use in organic potatoes, then production will only become more difficult in the future.
“Although blight-resistant varieties are available, these don’t necessarily meet consumer demand for cooking and taste qualities,” he said.
“This emergency authorisation is an important milestone for organic potato production, but there is still work to do to support organic production going forward.”
‘Strict guidelines’
Selchuk Kurtev, Certis’ head of integrated pest management, explains that strict guidelines must be followed when applying Cuprokylt.
Growers must ensure they have a hard copy of the EAMU and written recommendation from a BASIS-registered agronomist prior to application.
“Application timings must be based on a recognised disease forecast model, such as the widely used Hutton Criteria,” he says.
“Also, buffer zones of 18m from static water and 5m from the top of dry ditches should be left for water protection.”
Cuprokylt should be applied at a maximum individual dose of 0.85kg/ha combined with 1,100-1,300L of water.
Growers can implement six applications per crop with a 10-14 day interval between each one. The emergency authorisation will expire on September 28, 2018.
