The Chemicals Regulation Division (CRD) has approved the use of Funguran Progress (copper hydroxide) to control late blight in organic potato crops under an emergency use application.
Growers in England are able to use the fungicide until 30 September 2020 and have until 31 October 2020 to dispose of stocks.
Nick Badger, Certis UK potato product manager says this is good news for organic potato growers this season.
Growers using the fungicide must ensure any crops treated with the product are not exported to EU member states to avoid exceeding Maximum Residue Level restrictions.
Growers must also ensure that Funguran-treated potatoes are not fed to livestock.
AHDB knowledge transfer manager, Anne Stone says: “While fungicide sprays can be an effective part of blight control, many aspects of the potato crop affect its susceptibility to late blight and overuse can build up resistance. In the long term, the use of resistant potato varieties will be crucial to a sustainable blight management programme.
“Modern technology allows breeders to select varieties resistant to blight using genetic markers. Companies purchasing fresh market potatoes have named and listed new robust varieties, with many more coming through the development process.
While take-up of new resistant varieties is a slow process, organic growers can help by working with breeders, seed suppliers and customers to increase their use.”
In order to meet the two restrictions, the CRD has set out a series of stewardship arrangements.
Growers are advised to keep comprehensive records of their Funguran use. As well as adherence to the restrictions, any samples submitted by a grower to an organic certifying body may also be used by the CRD to support future applications for Funguran.
Growers who want to use Funguan must:
To apply Funguan Progress use a conventional hydraulic horizontal boom sprayer, keeping to a maximum dose of 2kg per hectare, Certis advises.
A maximum number of four applications is permitted, with a 10-day interval observed between treatments. The final treatment can be made up to the point when leaves and stems are dead, 14 days before harvest.
The maximum dose of copper substances from all sources, including non-plant protection uses, must not exceed 4 kg copper/ha per annum.
For further information and guidance from AHDB Potatoes visit ahdb.org.uk/potatoes.