Spraing is the word used to describe the brown lines that appear on the inside of potatoes. Also known as corky ringspot disease (CRS), this condition interferes with potato storage. And, hey, it doesn’t look very appetizing either.
Those brown lines can be caused by one of two viral diseases: potato mop top or tobacco rattle. They can also be caused by irregular watering, mechanical injury, and calcium deficiencies. There are other causes of brown marks inside your potatoes. We’ll get to those, too.
Potato mop top
Potato mop top virus (PMTV) is spread by the powdery scab fungus (Spongospora subterranea). The two entities work together to support each other. Since the fungus can remain viable in the soil for up to 18 years, it’s a good idea to ensure proper drainage. Leaves of infected plants have odd areas of bright yellow.
Tobacco rattle virus (TRV) is spread by nematodes as they feed. Infected plants may look normal aboveground, at first. Eventually, leaf mottling and distortion may be seen. Infected tubers exhibit necrotic arcs and lines both on the surface and inside. Leaves of plants infected with TRV may have localized yellow spots with green centers. Tobacco rattle is most common in sandy soils after it rains. This disease is best prevented by applying nematicides and planting resistant varieties.
Other causes of internal browning
There are several other causes of browning on the inside of potatoes, but symptoms look a little different from spraing:
How to prevent spraing
Investing in certified pest- and disease-free seed potatoes is the best way to avoid those brown streaks. Since irregular watering can lead to several problems, including hollow heart, splitting, and spraing, water regularly. Good drainage can also help prevent these problems.
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