How to Prevent Potato Scab

Potatoes are one of those easy to grow veggies that are a staple in most vegetable gardens as well as most pantries. Potatoes are a wonderful addition to the garden because they store so well. Any vegetable I can grow that will last all winter long is a must for my garden!

When you go to dig up those beautiful home grown potatoes only to realize they are covered in scabs, it can feel like such a let down. Scabby potatoes are still fine to eat once the scabs are removed, but pealing scabby potatoes can be a lot more work!

Me gathering potatoes from my no-dig potato bed.

You can learn more about the no-dig bed I grow my potatoes in here.

What Causes Potato Scab

Potato scab is caused by a bacteria (streptomyces scabies) in the soil. This bacterial thrives in alkaline soil. Unfortunately for those of us gardening in Alberta, Alberta is known for its alkaline soil. If you have grown potatoes for long in Alberta you have probably experienced potato scab.

How Does Potato Scab Bacteria Get Into Soil?

Potato scab bacteria typically gets into your garden soil through one of the following:

• Infected seed potatoes (the most common way)

• Compost that has had scabby potatoes or scabby potato peals put into it

• Fresh animal manure - potato scab can pass through the digestive tracts of animals

Unfortunately, potato scab can live for three or four years dormant in the soil.

How to Prevent Potato Scab

First off, always buy seed potatoes from a reputable, trusted source. I personally love Eagle Creek Seed potatoes, located in southern Alberta. If you have never had potato scab or if you have some scab free garden beds, be extra careful to plant scab free potatoes to keep the bacteria from entering the soil.

Once the bacteria has entered your soil, the best way to prevent potato scab is to lower your pH, ideally to 5 to 5.2. As mentioned earlier, potato scab bacteria thrives in an alkaline environment. Creating an acidic soil will greatly slow down and hopefully mitigate the presence of potato scab bacteria.

Elemental sulfur and peat moss are two ways to lower your soil pH. I have had success lower my soil pH with this 99.5% elemental sulfur from Amazon (this is an Amazon affiliate link from which I may earn a small commission. Peat moss is very acidic and also aids in creating a light texture soil that potatoes love to grow in. Add peat moss to a rate of up to half of your soil volume to help lower your soil pH.

Maybe the easiest of the ways to prevent potato scab is to plant scab resistant potato varieties. Scab resistant potato varieties include:

• Gold Rush

• Norland

• Russet Burbank

• Viking

Practicing crop rotation is anther great way to prevent potato scab.

Learn more about growing potatoes and the difference between determinate and indeterminate potatoes here.

You can also learn more about harvesting, curing and storing potatoes in this blog post.

If you have found this article helpful and would like to see more gardening tips and tricks for gardening in Alberta and other zone three gardening climates, please subscribe to my blog (the bottom of the home page) and follow me on Pinterest, Instagram, Facebook and/or YouTube!

References:

https://salisburygreenhouse.com/avoiding-potato-scab/