My red potatoes are really weird, what is wrong?

A:

This looks to be common scab. This is a bacteria that lives in the soil or can come in on seed potatoes. It usually attacks thin skinned potato varieties while the russet types are more resistant. It seems unusual that your Yukon Golds were not affected while the reds were. This may suggest that the reds came in infected. Did you buy certified scab free seed potatoes?

Other conditions can cause scab to occur. Hot, dry soil is one. So if you did not keep your soil consistently moist this may have been some of the problem. Also, adding raw or uncomposted manure can cause this as well as growing your potatoes in the same spot year after year. Low acid soils will also contribute to the problem. Most of central Oregon has neutral to slightly alkaline soils so if you also let the soil dry out between waterings this could be your main issue.

Since there are many factors that contribute to common scab you will need to look at your practices to see if you need to change some. For more information on this matter, see Cornell's article on potato scab. If the lesions do not go too deeply you can peel them off and eat the potatoes.

It may be a good time to do a soil test. You can get a kit from the Extension Office in Prineville if you are interested. 

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