What is on these horrible potatoes?

[Vanisle_BC]

I'm not familiar with potato diseases - blight, scab, whatever. Who can tell me what this is and what to do about it? I won't grow potatoes in the same place again, but how far away is far enough; other end of same bed, adjacent bed with 3 foot path between ... ??

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[Gary350]

I think your potatoes have scabs and it is caused by soil ph being too high. Some potato varieties are more sensitive to ph than others. I test my soil with ph paper so I know what it is. 8ph causes bad scab problems. 7ph my red Pontiac has scabs but it is not very bad it is easy to peel off with potato peeler. 7ph is no problem for my Kennebec potatoes. Russet & Idaho potatoes have small surface scab problem with 7ph. Russet & Idaho are the same potato you can not legally call russet an Idaho unless it is grown in the state of Idaho. Test your soil with ph paper see what you have. When I lived in Arizona soil & water were both 8ph. Now I live in Tennessee soil is 6ph but I added lots of organic material that made my soil be 8ph. December I put a 5 gallon bucket of sulfur on my whole 35'x60' garden it lowered soil ph from 8 to 7. I might need to add sulfur again this Dec to get soil down to 6ph but I will test soil first with ph paper. Information online says potatoes like 5.5ph to 6ph. If you add sulfur to your soil you can plant nothing for 4 months. If your potato crop is small buy kitchen vinegar by the gallon pour it on the soil. Test ph of your city water too. If your city water is high ph don't put it on your potato plants. I learned from experimenting that 1/2 cup of vinegar will lower 5 gallons bucket of 8 ph water to 6 ph. Don't put lime or calcium or wood ash on potatoes. Don't give plants much nitrogen or you get very large plants and no potatoes. I have tried several different fertilizers I think 10-20-30 is good 15 lbs in a 40 ft row. PH paper is 99¢ on ebay free postage from China.

If your potato crop has a disease don't plant in same place or you will have no crop the next year. So far so good I planted same place 2 yrs in a row but not next year. I want my corn crop farther north for more sun so potatoes crop needs to go south but still full sun for 12 hours.

[Vanisle_BC]

Thanks Gary; from looking online I was deciding the problem is scab as you suggest. I already have sulfur as my wife was given a Camellia and it too likes acid soil. But I'm sure I can get pH test papers closer than China. I'll buy local - it's my own, personal trade sanction .