Comments on: Help With Potatoes: Why Would They Have Spots??!

By: Melinda

Melinda — Thu, 12 Nov 2009 13:29:11 +0000

Gaye, on that same site are a whole bunch of other "fact sheets" about potatoes here. The one that might help the most is called "Detection of Potato Tuber Diseases & Defects".

By: Gaye

Gaye — Sun, 08 Nov 2009 20:57:38 +0000

Melinda & Kristi,

Thank-you Melinda for guiding me to the forum. And thank-you Kristi for the nice Cornell Veg MD.

I’ve had scab before, just like in the photos. But the problem I’ve described is not pictured. Perhaps it is a form of scab, since as the fact sheet states, scab can vary in its appearance. It is that little snaky thing that travels into the potato that “bugs” me! This characteriistic of my problem is not described.

Gaye

By: nic @ nipitinthebud

nic @ nipitinthebud — Sun, 08 Nov 2009 15:49:22 +0000

I’d agree it sounds like scab and could be caused by too much moisture or not enough depending on the kind of scab you have. Common scab has patches with ragged edges and is most likely found on potatoes planted in light soils under dry conditions. To prevent it next time dig in compost before planting and grow a resistent variety like Wilja.
If the patches have raised edges and are powdery to touch it’s more likely to be the less common powdery scab which is caused by wet conditions and heavy soils. Crop rotation is recommended to prevent recurrences.
Both forms of scab are harmless and don’t effect eating. Cutting all the bits out may seem a shame but at least it’s not a disease where you lose the whole crop like the blight we had this year that wiped out all our tomatoes.

By: Deb G

Deb G — Sun, 08 Nov 2009 14:48:28 +0000

That is a great fact sheet! I’ve tried adding pine needles to my potato beds. I don’t remember how much difference I thought it made. I usually just cut the scab out when I get it. The most beautiful potatoes I’ve grown were ones that I grew in potting soil but as Patrick said, it doesn’t really matter much.

By: Patrick

Patrick — Sun, 08 Nov 2009 08:08:13 +0000

Like the factsheet says, rotation and choosing resistant varieties are the most important things. In Northern Europe a lot of gardeners put grass cutting in the ground with the seed potatoes, which helps a lot. If you have access to grass cuttings, you might try this.

If you are really a gardening geek, and have a completely organic garden, some people are experimenting with inoculating their ground with other Streptomyces strains that don’t cause scab but displace the strains that do. Some people have reported success with this, and probably if you search around on the Internet you could find sources of inoculants.

When it comes down to it, scab is just cosmetic. If you can live with it, there’s nothing wrong with a few scabs on your potatoes.

By: Melinda

Melinda — Sun, 08 Nov 2009 06:10:11 +0000

For anyone clicking on Kristi’s link, make sure you scroll down to the bottom of the page for the photos – it was a bit confusing to me at first.

Kristi, Great resource! Loads of great articles there. I’ve emailed the reader, so hopefully she’ll let us know soon if that was it.

By: Kristi

Kristi — Sat, 07 Nov 2009 23:56:58 +0000

Does it look like this? http://vegetablemdonline.ppath.cornell.edu/factsheets/Potato_Scab.htm