Maintaining potato quality in store

27.09.2018

Pre-harvest advice

Potato growers continue to face numerous challenges in the field, many because of climatic conditions this season. Desiccation has been delayed in some parts of the country, subsequently impacting skin setting and potential harvest date. 

VCS Agronomy’s, Graham Tomalin, believes skin setting is also taking longer due to secondary tuber growth, resulting in late tuber maturity. 

Graham urges growers to harvest as soon as crops are fully skin set, assessing this by digging up samples in numerous locations within a field. It’s important to focus on the rose end of tubers, and field areas with immature canopies and significant secondary growth, as these will be the last to set skins.

To minimise disease risk going into store, he recommends maintaining blight protection programmes until canopy desiccation is complete. 

Assessment of potato damage and bruising going into store is also important. Target harvester and grader set-up changes to avoid creating possible entry points, which allow development of bacterial diseases.

Store management 

Adrian Briddon, Senior Scientist at AHDB Sutton Bridge, says temperature control in store is key to reduce disease spread, sprouting, and sugar content in potatoes.

Warm, dry weather has caused potatoes to physiologically age faster than usual, which is why growers are seeing early dormancy break in the field. It can also cause early onset of senescent sweetening at the end of the storage period.

Senescent sweetening is a problem in potatoes grown for processing, as an irreversible increase in sugar content causes a deeper brown fry colour, otherwise known as ‘Maillard browning’.

Optimum potato storage temperatures depend on potato variety and customer requirements.

Store temperature should be as low as crop quality allows, reducing weight loss, the spread of disease and sprouting pressure. However, Adrian warns that temperatures left too low will lead to increased concentrations of sugar in potatoes.

Crop protection
 

Morley Benson, Certis’ Field Sales Manager, advises that potatoes going into store damaged or diseased will deteriorate and affect the surrounding crop.

Therefore, as part of an ICM strategy, Morley recommends protecting crops grown for seed with Gavel to help control key storage diseases. One of Gavel’s strengths is the control of fusarium dry rot, which could be an issue this season. Importantly for Gavel, there’s no known resistance to fusarium dry rot.

Ware crops can be protected from sprouting by applying a growth regulant, such as Gro-Stop, and the sooner crops can be treated once lifted the better, to ensure efficacy. 

Gro-Stop should be applied in accordance with current CIPC guidelines. Consult the label for more information. For best results, potatoes should be clean and dry, with skins well set before early application.

Store management top tips:

• Ensure store environments are clean and cool

• Remove damaged and bruised potatoes

• Fill stores quickly with clean potatoes, ensuring skins are set well

• Apply Gavel to seed crops to limit disease

• Apply Gro-Stop to ware crops to avoid sprouting

• Monitor stores daily