The North America Potato Storage Organization (NAPSO) recently hosted an informative and impactful webinar, drawing the attention of professionals across the potato industry. The webinar was titled “Preparing for a Successful Storage Season”.
A highlight of the event was a detailed presentation by Todd Forbush, a seasoned potato storage specialist with Techmark, Inc.
His presentation, titled “Crossroads to Harvest,” offered an in-depth exploration of best practices for potato storage, with a focus on understanding the chemical maturity of potatoes as they transition from field to storage.
Forbush’s expertise illuminated several critical aspects of potato storage, emphasizing the importance of a holistic approach that integrates soil management, variety selection, cultural practices, and weather monitoring. His presentation served as a valuable guide for growers and storage managers aiming to optimize storage conditions and ensure the long-term quality of their potato crops.
The Four Pillars of Potato Storage: Soil, Variety, Cultural Practices, and Weather
At the core of Forbush’s presentation were four key factors that significantly influence potato sugar content and specific gravity: soil, variety, cultural practices, and weather. Each of these elements plays a pivotal role in determining the storage potential of potatoes, and understanding their interactions is essential for successful storage management.
1. Soil and Variety:
Forbush identified soil and variety as the most critical agronomic choices made by growers. The type of soil in which potatoes are planted, along with the specific variety chosen, greatly impacts the crop’s ability to develop the desired sugar content and specific gravity. These attributes are crucial for determining how well potatoes will store and their eventual processing quality.
2. Cultural Practices:
The management of cultural practices, including the use of fertilizers and chemicals, is another vital component. Forbush highlighted the importance of nitrogen management, noting that excessive or improperly timed nitrogen application can delay crop maturity, potentially leading to storage issues. Growers must carefully balance their use of fertilizers to ensure that the crop reaches optimal maturity before harvest.
3. Weather:
Mother Nature, Forbush explained, holds the wild cards when it comes to potato storage. The weather conditions during the growing season, particularly cumulative growing degree days (CGDD), play a significant role in determining the crop’s maturity. Forbush provided detailed guidance on how to monitor CGDD and assess the impact of stressful weather events, such as high nighttime temperatures or prolonged heatwaves, on potato development.
Pre-Harvest Sugar Analysis: A Crucial Step Toward Storage Success
Forbush’s presentation placed significant emphasis on the importance of pre-harvest sugar analysis in determining the maturity and storage potential of potatoes. This analysis, he argued, is a critical step that allows growers to make informed decisions about nitrogen management, vine kill timing, and storage conditions.
Understanding Tuber Sucrose and Glucose Levels:
Forbush explained that tuber sucrose and glucose levels, combined with canopy vigor assessments, provide valuable insights into the crop’s maturity. These metrics help growers determine whether the crop is ready for storage and what adjustments may be needed to optimize storage conditions. In particular, Forbush noted that understanding the relationship between canopy senescence and tuber development is essential for predicting storage outcomes.
Timing of Pre-Harvest Sampling:
Forbush recommended conducting pre-harvest sampling at least twice before vine kill or harvest—once three weeks prior and again within one week of vine kill or harvest. This practice allows for the collection of critical data on tuber sugars and specific gravity, enabling growers to fine-tune their nitrogen applications and other cultural practices to enhance storage potential.
Managing the Threat of Fall Frost: Strategies for Protecting Crop Quality
As the growing season transitions to fall, the risk of frost becomes a pressing concern for potato growers. Forbush outlined strategies for managing this risk, emphasizing the need to assess crop maturity before the onset of cold weather.
Cold Temperature Sweetening and Frost:
One of the key challenges identified by Forbush is cold temperature sweetening, a condition that occurs when potatoes experience frost or near-freezing temperatures in the field. This can cause a rapid increase in sugar levels, making the potatoes unsuitable for storage or processing. To mitigate this risk, Forbush recommended storing immature potatoes at temperatures above 52°F (11°C) to allow excess sugars to break down, while mature potatoes can be cooled to 50°F (10°C) or lower, which can improve their quality over time.
Importance of Pre-Frost Evaluation:
Forbush stressed that evaluating crop maturity before frost sets in is essential for making informed storage decisions. Immature potatoes that are exposed to frost require careful management to avoid post-harvest losses, while mature potatoes can be stored at lower temperatures with confidence that their quality will improve in storage.
Optimizing Storage Management: Cooling and Holding Strategies
Forbush’s presentation also provided a comprehensive guide to storage management, particularly cooling and holding strategies that are crucial for maintaining potato quality throughout the storage season.
Cooling Strategies:
Forbush emphasized that the cooling process should be tailored to the specific needs of the crop, taking into account factors such as the intended market (e.g., chip, fry, or table potatoes), the crop’s condition, and the variety being stored.
He recommended a cooling rates that range from 0.2°F to 1.0°F per day for potatoes based on the condition of the potatoes, the intended market, the presence of refrigeration in the storage and the availability of outside air for ambient cooled storage. The final holding temperature of the storage is dependent upon the market requirements and the crop’s sugar concentration.
Avoiding Over-Cooling:
Forbush cautioned against cooling healthy potatoes too quickly or to temperatures that are too low, as this can lead to excessive pressure bruise as well as rising sucrose and glucose levels, ultimately degrading the quality of the stored potatoes. He recommended monitoring sugar levels regularly throughout the storage season to ensure that the crop is maintained at the appropriate holding temperature.
Holding Temperature Considerations:
Proper holding temperature is critical for maintaining potato quality. Forbush advised that if sucrose and glucose levels are stable or falling, and the quality of the potatoes is improving after cooling, the holding temperature is likely appropriate. However, if sugars are rising and quality is deteriorating, the temperature may be too low, necessitating adjustments to avoid economic losses.
The Role of Disease Management in Storage Success
Another important aspect of Forbush’s presentation was the role of disease management in ensuring storage success. He emphasized the need to assess disease pressure in the field before harvest and to take preventive measures to minimize the risk of bringing disease into storage.
Assessing Disease Pressure:
Forbush discussed the importance of monitoring for signs of disease in the field, such as early die, blight, or other crop health issues. He noted that disease pressure can significantly impact the quality of potatoes in storage, making it crucial to identify and manage these risks before the crop is harvested.
Preventive Measures in Storage:
To minimize the risk of disease in storage, Forbush recommended taking a cautious approach when dealing with crops that have been exposed to disease pressure. This includes implementing rigorous storage management practices, such as storage ventilation and humidification control along with regular sugar sampling and careful monitoring of storage conditions, to prevent the spread of disease and preserve crop quality.
Collaboration and Knowledge Sharing: A Path to Continuous Improvement
In his closing remarks, Forbush underscored the importance of collaboration and knowledge sharing within the potato industry. He referenced a memorable quote from the late Dr. Burt Cargill: “The potato will never let us know all the secrets.” Forbush echoed this sentiment, highlighting the need for industry professionals to share their insights and experiences to continuously improve storage practices and achieve better outcomes.
The Importance of Industry Collaboration:
Forbush emphasized that the collective knowledge and experience of the potato industry are essential for unlocking the full potential of potatoes in storage. By participating in forums like the NAPSO webinar and engaging in open discussions, industry professionals can refine best practices and apply them to their operations, ultimately benefiting the entire industry.
Conclusion: Implementing Best Practices for Potato Storage
Todd Forbush’s presentation at the NAPSO webinar provided a wealth of practical information and actionable insights for potato growers and storage managers. His emphasis on pre-harvest sugar analysis, careful weather monitoring, and strategic storage management offers a comprehensive approach to maintaining potato quality from field to storage.
As the industry continues to face challenges such as unpredictable weather patterns, disease pressure, and market demands, the insights shared by Forbush will undoubtedly contribute to improved storage outcomes and greater industry-wide success. By adopting these best practices and continuing to share knowledge, the potato industry can unlock new levels of efficiency, quality, and profitability.
For those interested in further exploring the topics discussed in Forbush’s presentation, NAPSO encourages industry professionals to engage with Techmark, Inc., and participate in future NAPSO webinars and events aimed at advancing potato storage practices.
Cover image: Credit Todd Forbush
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