POTATO storage was never going to be easy this harvest, but new changes to in-store chemical applications will also complicate things.

The new product label recommendations CIPC (chlorpropham) product labels, aimed at lowering application rates, have recently been confirmed by the CRD (Centre for Reviews and Dissemination).

Critically, fans will be required as part of the application process. CIPC must be actively re-circulated during application and until the fog has cleared. The Potato Industry CIPC Stewardship Group (PICSG) has been running a ‘No Fan, No Fog’ campaign for three years in preparation for this decision.

And, the National Association of Agricultural Contractors' CIPC applicators group has confirmed that applications will not be made by their members if fog is not able to be recirculated.

There are also new statutory limits for total dose. Approved limit is 36g/tonne for processing and 24g/t for fresh market produce, and the maximum individual dose is reduced to 12g/tonne. Applications must also be made a minimum of 14 days before removal from store for sale or processing.

Additionally, 'best practice' allows just one application (now up to 12 g/t) in cold stores as CIPC residue declines more slowly at low temperature. This applies to all stores that will be held below 5°C.

Mike Storey, AHDB’s head of resource management and chair of PICSG, said:

“As the 2017 store loading season builds, many store managers will be considering their first CIPC apllication. The labels now state that best practice must be complied with and so it is a legal requirement that both an NAAC applicator is used to apply CIPC and active recirculation of the store air/fog takes place during and after treatment. This will help ensure compliance with the maximum residue level (MRL of 10 mg/kg).

"In stores with positive ventilation, active recirculation is achieved by fitting a variable frequency drive and using the store’s ventilation system. In overhead throw box stores, active recirculation can be brought about using an air separator or duct at the end of the store to create an ‘open suction’ system. Alternatively, fan-assisted plenums placed within box stacks will ensure active recirculation can be achieved," he added.