How to Prevent Potato Scab

After growing potatoes in the same location for several years, last year a couple of my potatoes had potato scab. It’s a good thing I decided to rotate the crops this year or I’d probably end up with a whole bunch of them this time around.

In case you don’t know, potato scab is basically a bacteria that builds up in the soil and then causes your taters to have gross lesions.  The worst part about potato scab is that usually you don’t even know your potatoes have it until you go to dig them up.   The good thing, is that preventing potato scab is pretty easy to do if you’re paying attention {unlike someone I know, ahem}.

The bacteria really only thrives in a pH level above 5.5, and taters like it between 5.0 and 5.5–so, while I’m not a mathmagician, keeping your pH level at about 5.0-5.2 will go along way in making a really inhospitable environment for the bacteria.  Testing the pH level of your soil will help you to know how to ammend it to achieve the perfect balance.

Another way to naturally manage potato scab is moisture.  The bacteria thrives in dry conditions, so a weekly irrigation of your potatoes really ticks off the bacteria.  (Just make sure not to go overboard, or you will have rotten potatoes.}

If you do get potato scab, it is essential that you rotate your crops.  It can survive in the soil for years, and without a host plant, it obviously can’t do any harm.  Your best bet is to plant a cover crop that will replenish the soil while the bacteria dies off–corn, rye and alfalfa are not susceptible to the bacteria, so they make good cover crop choices.

If you really want healthy dirt, plant a cover crop in the location for at least 3 years while you wait out the storm.

I know a lot of people don’t reuse their potato dirt at all once it has shown signs of disease, but I think with the cover crops I planted last fall and by simply rotating my crops I’ll be able to nurse my soil back to good health.

What have you done in the past to prevent potato scab?

~Mavis