Common Scab

Typical raised scab lesions.

Causal Agent:

Common scab is caused by several species of Streptomyces, a genus of bacteria that is present in all soils in huge numbers.


Most soils contain bacteria capable of causing potato scab, but exactly what conditions bring on symptoms is not fully understood. Scab-causing bacteria are constantly changing the arrangement of genes in their DNA, which may explain some inconsistency in field management.


  1. Reliable strategies are not known for scab prevention under all conditions.
  2. Avoid planting scabby seed tubers.
  3. Plant varieties with scab resistance when possible.
  4. Avoid application of soil amendments that increase soil pH.
  5. A generally healthy crop may help reduce scab intensity on tubers.

Further Reading:

Pacific Northwest Pest Management Handbooks

Consortium Members and Partners


Insects, Diseases, Nematodes, & Beneficial Organisms

Find out more information about insects, diseases, nematodes, and beneficial organisms for Potatoes.

About The Northwest Potato Research Consortium

In February 2012 the state potato commissions in Washington, Idaho, and Oregon officially launched a new cooperative effort in research. The aim of this initiative is to increase cooperation and efficiency of the research programs funded by the three potato commissions that total about $1.5 million annually. It will also work toward comprehensive research results reporting process that aims to get useful information to the growers and industry members who need it. This website is a big part of that effort. Research results, integrated pest management guidance, and production information of many kinds will be presented here. For feedback or suggestions on this site, please contact Andy Jensen, Manager of the Consortium.

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Research Library

A useful and resourceful research library available with a wealth of knowledge and insight into potato data from in field experience.

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