I absolutely agree with you. Purple Vikings are yummy...as well as good looking. For another delicious potato (more so, in my opinion) try Terra Rosa.

Yes, I have grown Gbutterball for years and noted those brown spots. It is itself low-yielding compared to Yukon Gold.

I believe it is well established that scab is directly correlated with soil ph. Sounds like lowering ph would help, if there were a way to do that affordably.

On the good side, you don't mention CPB, so I assume that means you don't have it there. You can therefor figure that you live in potato-growing heaven!

Hi pnbrown, yes, scab is a ph thing. I add lots of
handfuls of sulfur to my potato patch every year. And that seems to help, but with a bedrock of limestone, it's almost a losing battle. I grew Yukon golds and red pontiacs one year and they were basically one big scab with a potato inside. Still very edible, but UGLY! Montana, (being next door to Idaho) is a potato state. In fact my land was once a potato plantation back in the 40's. The soil is rife with the bacteria, so there's no curing it. Thankfully they are coming out with scab resistant varieties now, and German Butterballs and Purple Vikings both seem to be.

Sweet - do you know if Terra Rosa is scab resistant?

Sorry...I don't know. My soil is acid. I bought the seed potatoes from Grand Teton. Perhaps you could e-mail them and ask about any particular problems with them. Terra Rosa will be a yearly "must have" for me.

Lots of sulfur and do not plant your own saved seed will help with scab. I had great yields from Purple Viking this year.
Here is a comparison of two plants of each variety.
{{gwi:119320}}
Top left is Viking then Yukon or Keuka Gold is next. Adirondack Red is top middle then Yukon or Keuka is top right. Bottom right is Magic Molly, then Rose Finn Apple, Russet Burbank and then left bottom is Augusta Gold which is the highest yielding gold.

So then no CPB problem? I'd probably switch with you..

I use gypsum to help break up the clay soil that I have. Looks like it's used for scab as well. Ck it out.

https://www.google.com/#q=potatoes+scab+gypsum

Adding sulfur - how and how much? Probably irrelevant, but powder form or granular?

I do not have scab problems, but for years I have been wanting to experiment with sulfur for my potatoes to see if it improves the crop. I have slightly alkaline soil.

Generally speaking, I consider blanket applications of soil amendments and fertilizers inefficient, impractical, and wasteful. I prefer doing targeted applications instead. Based on how potato plants grow and set tubers I assume that for a targeted application of sulfur I would dig a hole, place the seed potato in the hole, barely cover that seed potato with dirt, and then apply granular sulfur to the compost/fertilizer/soil mix that I would use to fill the remainder of the hole.

Assuming that the above concept is valid, my main question is simply how much granulated sulfur to use in each hole (in other words, how much granulated sulfur to use per individual plant)? One tablespoon perhaps?

As long as I am asking questions, how much granulated fertilizer (and what NPK ratio) should be mixed into that "fill" soil mix for each plant?

Thanks for any help or advice.
-Tom

Potato Garden has a liquid product called Acton. I used it last year and will again in the future. Good stuff. You could phone them and ask about it.

pH OF POTATO SOIL:

Because of the SCAB issue, potato soil has to be acidic, pH of 4.8 to 5.5(I think). Then scab is not a serious disease if you don't intend to sell your potatoes.

It doesn't have to be that low, IME. I find scab doesn't appear much until over ph6.

Little minnie -- thanks for the comparison photo. Very informative.
And really good yields!
Did you do taste comparisons too? Im' wondering how the "golds" compare in a taste test -- are the Augustas as good as Yukons?

I doubt anyone could tell much difference with the golds. Yukons are known for poor yield compared to harder to find gold varieties. But you have shipping cost when buying less common varieties. So I saved myself plenty of Augusta for seed. Previously I had grown Keuka which did better than Yukon and seems very uninteresting to CPBs. Oddly here in potato country I saw only 1 or 2 all season!!!

I had my soil tested in fall 2012 and it was 7.3 IIRC and the soil here is sandy and alkaline by nature. Plus the drought increased alkalinity due to irrigation rather than rain. So I bought 40# of split pea sulfur from the farm chemical company in town and spread that. I meant to do another soil test this fall to see how far down it dropped but the garden produced so excellently I figured I would skip one year. I didn't get more sulfur this fall as intended but probably will in spring. The potato farmers here use truckloads of powdered sulfur and I guess it to be ammonium sulfate?

Potatoes around here seemed to have amazing yields this year. I had a crop failure last year and huge production this year. They sure love water! I grew half of my beds in black plastic mulch and half in pine debris mulch. Both did great but the pine debris mulch needed replenishing to avoid green shoulders and it didn't hold in moisture or hold back weeds as much. We had no bugs which was crazy weird but there was a little fungal problems. I sprayed a little sulfur and copper but mostly ignored it because the tubers were formed by then and it didn't spread to tomatoes. The farmers sprayed tons of chemicals for little effect. I am growing all my potatoes in black plastic next year with drip lines under and I use some mulch on top to help the stem area stay covered.

Tom,

Here's what worked for me this year and I had hardly NO scab, which is almost a miracle from my garden. I chose the site I wanted my potato patch and last fall I sprinkled granular sulfur in just that targeted area. (I'm not sure how much exactly, about the same as if I were scattering chicken-feed.) Sulfur doesn't work right away-it has to sort of "stew" in the ground, that's why it's recommended to be applied in the fall. Then in the spring I coated my seed potatoes in powdered sulfur and planted. It probably cost me less than $2.00. I'm thoroughly convinced tho, that it is the variety of potatoes I chose, rather than my methods that deserve the scab-free credit. It would probably take alot of sulfur to lower my 7.8 soil down to 5.5.

I don't use any fertilizer at all because my garden gets compost each year, but I'll tell you where I made a BIG mistake...going from advice from another poster on these forums. (This tip did not work for me.) Instead of hilling up the potatoes as they grow, it was advised to just use straw. Keep piling on the straw and in the fall digging is almost nil and no green shoulders. All true. Good advice perhaps for someone who doesn't have moles/voles/mice. I found out that I have way more of those critters than I imagined and they loved the nice cozy mountains of straw I provided for them over a buffet table of papas al gratuitous!

little minnie -- thanks for the info on the golds, and the details on your growing.
I always wish my potato yields were better, so I'm always interested in what people with great yields are doing.

My soil is naturally 5.4 PH, so I'm planning to open up a dedicated potato bed and not lime it, and rotate potatoes in and out of there.

runswithscissors - Thanks for your response to my question. I guess my preferred method of targeted applications will not work, but I am thinking of still trying it as an experiment in one row. A second row will have an application of ammonium sulfate. A third row will have an application of 10-10-10. Those three rows will be compared to a third row that uses just organic compost. Will be interesting to see the results. My main crop will be planted elsewhere using my usual planting methods.

I have not grown Purple Viking but based on comments here I plan on giving this variety a try. I normally plant Red Pontiac (and occasionally Red Norland), Yukon Gold, Russet Burbank, Kennebec White, and Russian Banana fingerlings. This last season I experimented with some new varieties with mixed results:

Red Gold - poor
Red Cloud - good
Carola - very good
Irish Cobbler - poor
German Butterball - good

The seed was purchased from out of state so I withhold ultimate judgment on these varieties until they have acclimated to my soil and local growing conditions. If all the varieties store well enough the entire harvest will be used for seed stock. It was fun to grow some new varieties after growing just the tried-and-true standards since the 1980s.

My Golden Yukons always produce low yields of very good quality potatoes and continue to be highly regarded by people who get them from me. Seed stock has always been cheap and readily available locally, so my solution has been to simply plant more Yukons rather than try to find a higher yielding substitute that might turn out to be a disappointment for whatever reason. That being said, I think I would be foolish not to give Augusta Gold a try. :-)