As harvest concludes across Northwestern Europe, storage facilities become the front line in determining crop value. The 2025 season delivered generally healthy yields, but weather variability and maturing crops have left store managers facing a delicate balance: preserving quality while avoiding early spoilage. 

According to industry specialists, careful control during the first few weeks in store will define whether that balance is achieved.

The Critical Early Stage

At the start of the storage cycle, two processes dominate: drying and wound healing. Both are essential to long-term quality. “The field quality looks very good,” notes Frank van der Linden, Senior Agronomist and Storage Specialist at Omnivent B.V., in the company’s Storage Advice Potatoes 2025 bulletin. Yet, he cautions that the physiological age of many lots — accelerated by drought stress — makes them more vulnerable to bruising and infection. “Damp soil and rotten tubers should be dried as quickly as possible to ensure long and trouble-free storage,” he advises.

Omnivent recommends beginning with full-capacity ventilation and, when necessary, using gentle heat to reduce relative humidity so that outside air remains effective for drying. Van der Linden warns against allowing tubers to cool too soon, as incomplete healing can lead to Fusarium or soft rot later in the season. His guidance sets the minimum temperature for wound healing at 10 °C, ideally 12–15 °C, for about 7 to 14 days. At these levels, the skin closes small wounds, creating a barrier against pathogens.

Once the product is dry, cooling should proceed slowly — about 0.5 °C per day for processing potatoes and 0.3 °C per day for seed lots — until the final temperature is reached in early December. Cooling too quickly, Omnivent notes, risks condensation and quality loss.

Lessons From 2025 Weather Patterns

The season’s weather created uneven field conditions: some lots were lifted dry, others after rainfall, leaving variable moisture levels at loading. These differences call for flexible ventilation control.

Storage technology provider Tolsma-Grisnich B.V. advises operators to base ventilation decisions on dew-point differentials rather than fixed hourly programs. The company’s guidance stresses “smart ventilation” that uses real-time data on air humidity and crop temperature to prevent re-wetting. In practical terms, this means alternating between outside-air and recirculation modes as weather shifts.

This approach mirrors Omnivent’s recommendation to maintain a small but positive dew-point difference (outside air slightly drier than the product) during the drying period. Such precision helps managers avoid moisture fluctuations that can promote soft rot or silver scurf.

Uniformity And Airflow Checks

Temperature uniformity remains a fundamental requirement in any type of storage, whether bulk or box. Omnivent advises completing loading within a single day whenever possible; if not, partial loads should be ventilated between batches to equalize internal temperatures.

Before continuous operation, stores should undergo a full mechanical inspection: ducts and shutters must seal properly, fans should deliver even airflow, and no cold or dead zones should remain. Even a small air leak can unbalance pressure and cause moisture pockets. While modern climate computers automate many adjustments, physical verification — using smoke or simple airflow meters — remains best practice.

Managing Relative Humidity

Omnivent’s 2025 recommendations call for maintaining around 85 % RH during wound healing and then raising it to about 95 % for the holding phase. Higher humidity at lower temperatures minimizes shrinkage without risking condensation.

Publicly available storage guides often recommend slightly higher humidity (90–100 %) throughout, but Omnivent’s parameters are optimized for its system configurations and European conditions. Regardless of the chosen settings, the key is stability: rapid fluctuations in humidity or temperature create stress in tubers and accelerate sprouting.

Sanitation And Disease Vigilance

While 2025’s crop entered storage in generally good health, vigilance remains crucial. Pathogens such as Fusarium and Pectobacterium can multiply rapidly under moist conditions. Technicians should inspect piles frequently during the first two weeks, removing any suspect pockets of dampness or decay.

Between seasons, thorough sanitation of ducts, walls, and ventilation components should be standard procedure. Disinfecting with approved agents before loading a new crop eliminates lingering inoculum and ensures consistent air quality.

Read the rest of this feature in the complimentary e-copy of the November / December Issue of Potato Processing International, which can be accessed by clicking here.