Two Tips to Improve Your Potato Seed Stock

Two Tips to Improve Your Potato Seed Stock

Examples of Fusarium dry rot of potato

Fusarium dry rot
Photo by Bonnie C. Wells

The front line of any potato production system is high-quality, productive seed from a high-performing cultivar. Defective, unproductive seed leads to a low stand that not only directly compromises the yield and quality of the crop, but also lowers the efficiency and cost-effectiveness of nutrient and pest management programs.

Here are two steps you can take to ensure you have the best seed possible.

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1. Take Action to Deter Disease Prevalence

Physiological condition of seed tubers is influenced by proper handling and storage. Growing-season stress, storage temperature and time, as well as loading/unloading, transport, and cutting all provide opportunity for bruising, wounding, splitting, cold injury, and other physiological conditions to ensue.

Potatoes bruise easily and a 6-inch drop or higher should be avoided. Bruises, wounds, and splits serve as pathogen entry points. Diseases caused by wound-entering pathogens include early blight and Fusarium dry rot.

All cultivars are susceptible to these storage pathogens, so warm environments should be avoided with wounded potatoes. The wound-healing stage is critical in tuber storage. A wound-healing environment has a high relative humidity (90% to 95%), is well ventilated, and maintains a temperature range of 45°F to 50°F.

When cutting seed pieces, keep cutting implements disinfected to avoid pathogen transfer and sharp to avoid tearing damage.

Low oxygen storage environments can cause increased tuber aging and reduced germination. Low oxygen also leads to excessive moisture environment that can cause enlarged lenticels and increased susceptibility to bacterial soft rot pathogens.

Maintaining proper temperature is critical, as heating speeds tuber aging, and temperatures less than 38°F can cause cold injury that reduces germination and favors bacterial soft rot development.

2. Seek and Secure High-Quality Seed Stock

Obtaining certified seed stock with a guaranteed low incidence of disease should be the first step of any potato management program.

Most seed producers in the U.S. have a seed certification program that provides a North American Certified Seed Potato Health Certificate to buyers. Certification programs produce high-quality seed stock; however, all pathogens cannot be eliminated entirely, so suppression is key.

Certified seed stock shipments should be inspected and evaluated before accepting them. Visual inspections should be performed carefully, examining the seed closely for both external and internal symptoms. Seed also should be cut to inspect for internal symptoms, such as discoloration and rot, because sometimes these symptoms are not visible from the outside.

If possible, growers should visit the site of production to observe field and storage conditions of their seed stock. Make sure to ask your suppliers for: certified seed certificate; size and grade; cutting preference; shipping details; and any potential field problems that occurred during the season.

Planting certified seed is only the first step to reducing seedborne diseases. Other integrated pest management strategies such as seed treatments and in-season disease monitoring also should be implemented to guarantee a productive potato crop.

Watch for New Pathogen in Your Crop

Dickeya chrysanthemi of potato

This potato is showing symptoms of Dickeya chrysanthemi.
Photo by Bonnie C. Wells

A relatively new bacterial disease to the U.S. joins other notorious potato diseases like late blight, scurf scab, bacterial ring rot, black dot, and bacterial soft rot: Dickeya dianthicola.

Dickeya is an aggressive pathogen that has devastated potato crops in the mid-Atlantic region, and has recently been detected in Pennsylvania, Maryland, Virginia, North Carolina, West Virginia, and Florida on potato seed stock sourced from Maine and Canada. Potato growers throughout the U.S. are on high alert and should monitor seed stock for Dickeya and other seedborne diseases.

Example of Dickeya dianthicola of potato

Here is a side-by-side image showing exterior and interior symptoms of Dickeya dianthicola.
Photo by Clay Pederson