Can you share some good practices for storing potatoes?
Answer: Good storage should prevent excessive dehydration, decay and sprouting. Maintaining good sanitation, adequate humidity and appropriate temperatures in storage facilities, combined with adequate curing of harvested potatoes, are important considerations, particularly since organic growers do not have the array of chemical controls available that conventional growers have. Helpful practices include:
• Thoroughly clean the storage space and machinery of all potato debris and excess dirt, using a pressure washer and steam as needed.
• Disinfect equipment and the storage structure with organically approved materials and methods. Contact your certifier for more information.
• Perform routine maintenance and repairs on ducts and structure as needed.
• Clean dust, dirt and sprout inhibitors from fan blades.
• Check dampers and louvers for free movement and function of limit switches.
• Be certain all motors are lubricated and working and that belts are in good condition.
• Check all thermostats, humidistats and controls.
• If needed, wet the storage floor to help maintain high humidity.
• Humidify and pre-cool the storage area to from 55 to 60 degrees a few days before introducing the potatoes.
A major component of managing potato quality in storage is effective sprout inhibition. Sprouting causes increased weight loss, reduces tuber quality and impedes air movement through the potato pile. Prevention of sprouting is one of the Achilles’ heels of storing large quantities of organic potatoes. The use of essential oils and hydrogen peroxide is a recent development in sprout inhibition and is approved by the USDA National Organic Program (NOP).
Mint and clove oils applied through wick application are effective at suppressing sprouts. The oils appear to work by burning the sensitive meristimatic sprout tissue. Although both oils have suppressive qualities, peppermint oil tends to cause less problems with culinary and palatability concerns. Clove oil is a more effective suppressant when applied as a thermal aerosol.
Hydrogen peroxide is also allowed by NOP standards, however some products may contain adjuvants that are not allowed. Check with your certifier to make sure products are approved by the NOP. Oils are typically applied through the humidification system in storage. Frequent and repeated applications are necessary for long-term sprout control. These products also demonstrate the ability to inhibit postharvest diseases in laboratory studies, but this research has not been extended to storage facilities (Frazier et. al., 2004).
Ready to learn more? Check out the ATTRA publication Potatoes: Organic Production and Marketing. This publication outlines approaches to organic and sustainable potato production. Practices include fertility and nutrient management; organic and biorational pest management for insects, diseases and weeds; and storage and marketing.
Frazier, Mary Jo, et al. 2004. Organic and Alternative Methods for Potato Sprout Control in Storage. University of Idaho Extension.