Pacific Northwest 1998 An Online Guide to Plant Disease Control

FactSheets offer superior print quality for the page you are currently viewing. Using Microsoft's Internet Explorer has given best printing results.
Glossary
Guide Home
Search

OSU Extension Office
 
Potato (Solanum tuberosum) -- Leak
 
Cause: Pythium debaryanum and P. ultimum, soilborne funguslike microorganisms. The disease is associated with high temperatures at digging time or in early storage and shipment. It also has been a problem on new lands in the Columbia Basin. The pathogen is attracted to the tuber's skin and can attack directly. Irrigation practices do affect disease incidence. Overwatering, clearly shown by increased incidence in the first tower of a center pivot irrigation system where more water is applied, does impact disease levels.
Symptoms: Decayed tissue is brown or gray; its uniform texture resembles a soft, watery paste. Margins of rotted tissues are sharply defined and darker in color. Tubers may develop a sour odor. They may eventually dry and mummify. Generally this disease rots the tuber from the inside out, leaving only a thin papery shell, sometimes called "shell rot." Rots to tubers are also caused by late blight, bacterial rot, and pink rot.

This tuber is severely decayed.

 
Cultural control:
  1. Prevent tuber injury during harvest.
  2. Keep tubers as cool and dry as possible during harvest.
  3. Store promptly at low temperature (45 to 50°F).
  4. Maintain storage at 90 to 95% relative humidity as soon as tuber surfaces dry.
Chemical control: One application when plants are flowering has been shown effective in Colorado. A second application two weeks following the first application has an increased benefit. New in furrow application at planting reduces cost over two aireal applications.
  1. Agri-Fos at 2 to 5 quarts/A in 10 gal water as a furrow spray applied in a band spray directly over top of row just before row is closed or 1.25 quarts/A in 90 to 375 gal water applied as a foliar spray on 5- to 14-day intervals 4-hr reentry.
  2. MetaStar 2E AG at 1.68 fl oz/1000 ft row. 48-hr reentry.
  3. Quadris Ridomil Gold at 0.82 fl oz/1000 row feet applied in furrow using 3 to 15 gal/A of water. See label for reentry intervals.
  4. Ridomil Gold Bravo SC at 2.5 pints/A following tuber initiation when the largest tubers are the size in diameter of a nickel. Make a second application 14 days later. Under severe pressure a third application may be made 14 days later. Do not use within 14 days of harvest. 48-hr reentry.
  5. Ridomil Gold SL at 0.42 oz/1000 row feet on a 6- to 8-inch band width at planting or Ridomil Gold SL at 0.42 fl oz/1000 row feet in furrow at planting. 48-hr reentry.
  6. Ridomil Gold MZ at 2.5 lb/A. Do not use within 14 days or harvest. Note Contains an EBDC fungicide, so take care not to exceed seasonal limits. 48-hr reentry.
  7. Ridomil Gold Copper at 2 lb/A. Do not use within 14 days of harvest. Do not use with Polyram. 48-hr reentry.
Content edited by: Phil Hamm and Cynthia M. Ocamb on January 1, 2010
 
Top

In print since 1954 and on the web since 1996. Questions or comments, please contact us.