Help With Potatoes: Why Would They Have Spots??!
Posted by Melinda on Saturday, November 7th, 2009
Hope you’re having a lovely weekend, everyone. I received an email this morning from a reader having trouble with her potatoes, and I was wondering if any of you potato experts could help her. I haven’t had troubles with potatoes - ours just grow and produce lovely scrumptious potatoes - so I have no idea what it is!
Hi, I have grown potatoes for years and every year I have the same problem. The literature doesn’t seem to define it well. The problem is small dark brown or black spots on the surface of the potato which are approximately 1/16th to 1/8th inch in diameter. The spot travels into the potato for 1/4 to 1/2 inch with a sort of rope or dry string-like material also dark brown or black. I always remove these with a knife before cooking. Sometime there are 5-6 of these spots on a potato. But sometimes many more. Although I expect to find an insect or burrowing creature, I never have. Any ideas?
Please help if you know, or have any resources!
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Filed in Gardening, The Growing Challenge |
Kristion 07 Nov 2009 at 4:56 pm 1Does it look like this? http://vegetablemdonline.ppath.cornell.edu/factsheets/Potato_Scab.htm
Melindaon 07 Nov 2009 at 11:10 pm 2For 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.
Patrickon 08 Nov 2009 at 1:08 am 3Like 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.
Deb Gon 08 Nov 2009 at 7:48 am 4That 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.
nic @ nipitinthebudon 08 Nov 2009 at 8:49 am 5I’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.
Gayeon 08 Nov 2009 at 1:57 pm 6Melinda & 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
Melindaon 12 Nov 2009 at 6:29 am 7Gaye, 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”.