ST. CLOUD - Have you ever picked up a fruit or vegetable and noticed that it had an odd shape to it and wondered how it got there? Recently, a gardener dropped off some potatoes at the Extension office that were misshapen and had several deep cracks. I have had several misshapen fruits and vegetables enter my kitchen over the years and this week I wanted to explore why this happens in potatoes.

The deformities that were seen in the potato that was brought in are called growth cracks. They are seen as deep cracks in the potato that are only a physical condition and not a biological one. Growth cracks are mainly esthetic. The only negative is that they may reduce the quality of the potato which can make it unattractive to buyers. Although the potato may not look the best, it is still safe for consumers to eat.

The deformities seen in potatos are called growth cracks. Photo illustration, Shutterstock, Inc.
The deformities seen in potatos are called growth cracks. Photo illustration, Shutterstock, Inc.

Growth cracks start to form when the potato experiences shifting environmental conditions. The causes can relate to uneven soil moisture, fluctuating soil and air temperature, and rapid water uptake which causes a spurt in growth in the potato (Hiller and Thornton 2008; Jefferies and MacKerron 1987). Potato growers as well as gardeners may see an increase in growth cracks when poor growing conditions suddenly transition into great growing conditions. Growth cracks become more severe when potatoes are spread further apart in a plot, are planted at a low soil density, and when fertilizer is applied unevenly.

The best way to have perfectly smooth potatoes and reduce growth cracks is to keep up the right amount of soil moisture during the growing season. Other ways to reduce growth cracks in potatoes are to irrigate evenly, apply the recommended amount of fertilizer, and plant potatoes at an equal distance from the other. It is important to remember that growth cracks in potatoes are merely esthetic and are still safe for consumers to eat.

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Sources in this article are linked here: https://z.umn.edu/potatodeformities. If you have questions about this or any horticulturally related topic, please reach out to your local Extension Educator.