Important Harvest Reminders

Watch for mechanical injury, foreign material and pulp temp

Published in the September 2012 Issue Published online: Sep 13, 2012 Phillip Nolte, UI extension seed potato specialist

There are a great many details that must be taken into consideration when the potato harvest is about to begin. Some of the most important details include taking measures to avoid mechanical damage or bruising in your potatoes, and taking care to ensure that the tubers are in the recommended temperature range when they're lifted and place into storage.

Mechanical injury is a detail that probably can't be totally eliminated, but steps can be taken to keep tuber damage to an absolute minimum. Naturally, machinery should be properly adjusted to avoid mechanical injury to tubers during lifting, transporting and piling. Maybe you remember seeing some mechanical damage in the crop you harvested last year. Do you know where along the transport chain the injury was occurring? An inspection of your transport line might just help you identify the problem area.

Some problems are relatively easy to spot and correct. Drops exceeding six inches in height between the different types of transport machinery should be avoided at all costs. Keep an eye on the potatoes as they are being transported on the conveyors or off the back of the truck. Perhaps a minor height adjustment or bit of extra rubber padding here and there will address some of the problem areas on your transport chain. An occasional inspection after the harvest is under way is also recommended. Machinery often gets moved around and repositioned.

Naturally, the harvester and crossover are machinery where it is possible to inflict a great deal of damage. Operate these at the highest possible capacity. Years of research have demonstrated that the best thing you can use to cushion potatoes and insulate them from damage is other potatoes.

Wounding is bad enough, but real problems can occur if damage is inflicted while tubers are at high pulp temperatures. Several severe storage disease problems are greatly favored by wounding in combination with high pulp temperatures. Pythium leak, pink rot and Fusarium dry rot are all favored by these conditions. Even diseases that are often not a problem in stored tubers, like early blight for instance, can be greatly favored by this unhappy combination of negative factors.

Another detail to keep in mind is taking measures to avoid foreign materials in your harvested potatoes. Foreign objects in potatoes can cause real headaches for processors. Any time consumers get involved, the entire industry suffers. The University of Idaho has a publication and a video available on the management of foreign material available on our website at: www.cals.uidaho.edu/potatoes. While you're logged in, check out some of the other harvest-related publications that are available at the site.

Before harvest begins would be a good time to check out your transport and harvesting machinery to ensure you don't have some problems brewing. Make sure your storage facility and the surrounding area are free of foreign materials. During harvest, keep a careful eye on the temperature.

Pulp temperatures at harvest above 65 degrees F should be avoided if at all possible. If pulp temps are too warm, you may be able to pull cool nighttime air. Some producers may be able to take advantage of an evaporative cooler if their storage is so equipped. On the other end of the temperature scale, avoid harvesting tubers below 45 degrees F. All types of potato bruising increase with lower temperatures but shatter bruise injury is greatly enhanced when tubers are cold.

As always, prevention is absolutely the best option for managing harvest-related and later storage problems. Be ready beforehand. Have a good harvest season! 

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