Potato scab is caused by an organism called Streptomyces scabies, which lives in the soil and garden debris along with fresh manure. While this plant disease is not fatal, it does cause unsightly markings on tubers such as potatoes, beets, parsnips, radishes, carrots, and rutabagas.
These unsightly markings can be circular in nature with a brown, pity appearance. This disease can just cover a small area or encircle the entire tuber.
This plant disease enters the plant through its pores on the stem, and leaves. If the seed tuber is damaged in any way, this is another enter point for this disease.
Once you have potato scab, there really is not much you can do. The key is prevention. The tips below will help you avoid an invasion of potato scab in your garden space.
- Potato scab loves soils that are slightly alkaline. To reduce the chances of developing potato scab, adjust your soil pH slightly. Prior to doing this though, make sure to take a soil test. A simple one that can be purchased for a few dollars will work fine. If you find that your soil is slightly alkaline, add elemental sulfur.
- Since this plant disease can survive in the soil even when potatoes are absent, it is imperative to rotate your crops. This means you rotate anything that has a tuber. Doing this simple step will help prevent the plant disease from building up in the soil.
- Plant only seed and/or plants that are resistant to the potato scab.
- Plant a cover crop in the area you plan to plant any tuber crop in the next year. Then, the following year, till the cover crop under. This is step will prevent the organism from taking hold in the soil.
- Lastly, monitor the soil moisture. Once the plant emerges from the ground, carefully monitor the soil moisture for the next two weeks. This appears to be a critical time for the plant material and the most opportune time for the potato scab to attack the plant.
Yes, as you can see the potato scab will not affect the taste of the potato or other tuber vegetables. The only thing it really does is make the vegetables appear unsightly. If you choose not to eat your tubers that have been attacked by the potato scab, remember not to compost them. This simple process will continue the infestation anywhere you use the seasoned compost.