Challenges aplenty for harvest and the storage season ahead

Reports from around the country indicate that there is a challenging season ahead in most of England & Wales, with only the far north of England and Scotland showing any immunity from the impact of the hot and dry summer.

A crucial part of storage is to have adequate skin set and this is proving very difficult to achieve with reports of 4–6 weeks gap from defoliation to lifting not uncommon. Where growth has been extended for yield, there are concerns of late (November) harvest, which will increase the likelihood of crops entering store at low temperatures and with higher moisture levels.

Secondary growth is reportedly rife across many crops that have suffered from drought and high temperatures. Such has been the demand for water from crop canopies that this physiological effect even extends to irrigated crops. Marked differences in dry matter content are also evident on such tubers, which may well lead to variable cooking and frying quality. The associated dormancy break and sprouting in the ground highlighted in our last bulletin appears to be widespread and linked to secondary chain tuberisation with granddaughter tubers reported to be as large as 50 mm in some crops. These immature tubers will be easily scuffed at harvest and provide an easy entry point for diseases, so some sorting of the crop at loading is likely to pay off if long term storage is planned.

Diseases are an issue across the country, but this varies hugely at the regional level. Blight is present in some regions and will continue to be a threat as green crops are slow to die off and re-growth takes place. Bacterial and fungal rots will exploit warm, moist conditions if these persist; cooler conditions will cut this risk as long as stores don’t take too long to load and damage levels are low. Ideally stores should be closed and under control in 7–10 days maximum.

Early application of sprout suppressants will be required to take control of the crop and the best chance of achieving this is with the maximum individual dose of CIPC (12g/t) applied under optimal conditions for even distribution – visit the Be CIPC Compliant website for label requirements. Remember that the total dose cannot exceed 36 g/t on processing crops and is limited to a single application of 12 g/t for crops held below 5°C; other fresh market crops can have a maximum of 24 g/t.

Where crops are suffering to a lesser extent from the impact of drought, there has been some good bulking in recent weeks, with varieties like Markies, Royal and Cultra reported to be performing well. The downsides of late harvesting remain a threat if this is not balanced with the need to get crops burned off to ensure a dry and sound crop goes into store.

Best practice advice is available from the AHDB Potato Store Managers Guide and from crop storage specialists on the Storage Advice Line 0800 02 82 111.

Potato store managers' guide

More on harvest and storage