Understanding Potato Blemishes: Is It Safe to Eat Potatoes With Warts?

October 7, 2025 •

4 min read

While potato wart disease does not pose a threat to human health, agricultural authorities consider severely diseased tubers unfit for human consumption primarily due to appearance and quality issues. This raises the question for many home cooks and gardeners: Is it safe to eat potatoes with warts, or are these growths a sign to discard the entire batch?

Quick Summary

Potato wart is a fungal agricultural pest, not a food safety risk to humans. Affected potatoes are usually discarded due to cosmetic damage and poor texture, not toxicity. It is important to distinguish true wart from other common, harmless blemishes like scab, which are perfectly safe after peeling.

Key Points

No Human Health Risk: Potato wart, a fungal disease, is not harmful to human or animal health, though affected potatoes are aesthetically undesirable.
Discard Diseased Tubers: Potatoes with true wart disease are considered unfit for consumption due to texture, appearance, and the need to prevent pathogen spread, not for safety reasons.
Peel Common Scab: Common scab is a bacterial infection causing corky patches that is harmless. Simply peel the affected skin and the potato is safe to eat.
Recognize Swollen Lenticels: Small, white, bumpy pores are swollen lenticels from wet soil conditions. They are normal and safe to eat once washed.
Cut Out Bruised Parts: Internal black or brown spots are bruises from rough handling or storage. Cut out the discolored parts, and the rest is safe to consume.
Properly Dispose of Wart: Do not compost truly infected potato wart, as it can spread the persistent fungus. Dispose of it according to local agricultural guidelines.
Practice Good Storage: Keep potatoes in a cool, dark, and dry place to prevent many blemishes, including swollen lenticels and internal bruising.
Know Your Potato's Origin: Store-bought potatoes are less likely to have true potato wart due to regulation; blemishes are often benign. Be more vigilant with home-grown crops and report suspected wart to authorities.

Navigating Blemishes: A Guide to Safe Potato Consumption

For home gardeners and consumers, encountering an imperfect potato is common. From green patches to sprouting eyes, potatoes can develop various imperfections. A particularly alarming sight, however, is a potato covered in what look like warts. While the cauliflower-like growths are visually unappealing, understanding their cause and differentiating them from other harmless blemishes is crucial for making informed decisions about food safety and minimizing food waste.

What Exactly is Potato Wart?

Potato wart is a plant disease caused by the soil-borne fungus Synchytrium endobioticum. This fungus invades the meristematic tissues of the potato plant, leading to the proliferation of abnormal, tumor-like growths, or galls. These warts are initially white and pulpy but turn black and rotten as they decay.

Key Characteristics of Potato Wart:

Cauliflower-like, warty growths on the surface, usually developing from the eyes.
Distorted and spongy texture in severely infected tubers.
Caused by a persistent fungus that can survive in soil for many years.
Mainly affects potatoes, though related plant species can sometimes be affected.

Is Potato Wart a Health Risk for Humans or Animals?

One of the most reassuring facts about potato wart disease is that it poses no risk to human or animal health. The fungus is a plant pathogen that induces abnormal growth in the potato tuber, but it does not produce toxins harmful to people. This means that accidentally ingesting a small, affected piece of a potato with wart disease is not a cause for panic.

However, while the wart itself is not toxic, authorities still advise against consuming diseased tubers. The primary reasons for this recommendation are:

Aesthetic and texture issues: The warty growths and spongy texture of an infected potato are unappetizing.
Unmarketability: The severe deformation makes the potatoes commercially undesirable.
Spread of the pathogen: Consuming infected potatoes could lead to the fungus's resting spores passing through an animal's digestive system (if fed to livestock) and re-entering the soil via manure, contributing to the spread of the disease. For home gardeners, this means discarding affected potatoes in a way that doesn't re-contaminate soil (e.g., not composting them).

Distinguishing Wart from Other Blemishes

The term "warts" is often used colloquially for any bumpy growth on a potato, but several conditions can cause different types of blemishes. Knowing the difference helps determine if a potato needs to be discarded or can simply be peeled.

A Comparison of Common Potato Blemishes


Feature	Potato Wart (Synchytrium endobioticum)	Common Scab (Streptomyces scabies)	Swollen Lenticels	Internal Bruising
Cause	Soil-borne fungus	Soil-borne bacteria	Excess soil moisture	Impact during harvest/storage
Health Risk	None to humans/animals	None, but peeling is recommended	None	None
Appearance	Cauliflower-like, spongy, warty growths	Raised or sunken corky patches	Small, white, raised bumps or pores	Internal black or brown spots
Action	Discard (dispose of properly)	Peel affected areas, then cook	Wash and cook as normal	Cut out affected spots, then cook
Severity	Can lead to total distortion of tuber	Varies from superficial to deep pitting	Generally mild, depends on soil saturation	Mild discoloration; worsens over time

Best Practices for Dealing With Blemished Potatoes

When faced with potatoes that are less than perfect, here's a step-by-step approach to ensure you're handling them safely:

Identify the Blemish: Determine if the potato has true wart disease or one of the more common, harmless blemishes like scab or swollen lenticels by referencing the comparison table above. True wart growths will be spongy, cauliflower-like masses, often originating from the potato's eyes.
Properly Discard Potato Wart: If you have confirmed the presence of potato wart, do not consume the potato. Instead of composting it, which could spread the pathogen in your garden, dispose of it properly according to local waste guidelines. These guidelines are crucial for controlling the spread of this regulated plant pest.
For Harmless Blemishes, Peel and Enjoy: For issues like common scab or internal bruising, the potatoes are perfectly edible. Simply use a peeler or knife to remove the affected skin or discolored flesh. Wash the potato thoroughly before cooking. In the case of swollen lenticels, no special action is needed beyond a good scrub.
Store Properly to Prevent Blemishes: Many blemishes develop due to improper storage. To minimize issues, store potatoes in a cool, dark, dry, and well-ventilated space to prevent sprouting, greening, and excess moisture build-up.

Common Sense and Context:

When purchasing potatoes from a store, blemishes are less likely to be true wart disease due to agricultural regulations. The more common issues are scab or physical bruising. In these cases, it's generally safe to simply cut away the bad parts.
If you are a home gardener and suspect true potato wart, contacting your local agricultural extension or plant health authority is the responsible course of action. This helps contain the spread of a significant agricultural pathogen. The Canadian Food Inspection Agency (CFIA) and the USDA's Animal and Plant Health Inspection Service (APHIS) are examples of such organizations.
If a potato is soft, mushy, or accompanied by a foul smell, regardless of the blemish, it's a sign of rot and should be discarded.

Conclusion

While the sight of warty growths on a potato can be startling, the good news is that they do not pose a direct health threat to humans. The recommendation against eating truly wart-diseased tubers is based on quality and the need to prevent the spread of an agricultural pest. For other common imperfections like scab, swollen lenticels, or bruising, a simple wash and peel is all that's required. By understanding the different types of potato blemishes, you can confidently decide what to discard and what to safely cook and enjoy, minimizing food waste while protecting your health.

For more detailed scientific information on potato wart disease, the National Institutes of Health provides a comprehensive review of research status and management strategies: PMC3964305

Frequently Asked Questions

No, potato wart is not dangerous to eat. The fungal disease is an agricultural pest and is not a threat to human health or food safety.

Potato wart is a fungal infection causing large, cauliflower-like growths that are often spongy and distort the tuber. Potato scab is a bacterial infection that causes corky, cosmetic patches on the skin. Potatoes with scab are safe to eat after peeling, while potatoes with true wart disease are typically discarded.

While the fungus itself isn't a human health threat, severely infected potatoes are often spongy and distorted, making them unappealing. It is generally recommended to discard the entire tuber to prevent spreading the pathogen, especially if it was home-grown.

You should not compost potatoes with true wart disease. Because the fungus is persistent, the best practice is to dispose of them according to your local agricultural authority's guidelines to prevent further spread.

These are likely swollen lenticels, which are pores that swell in wet conditions. They are perfectly harmless and the potato is safe to eat after a thorough washing.

No, the potato wart fungus is not harmful to animals. However, feeding infected tubers to animals is discouraged because the fungus's spores can survive digestion and be spread via manure, re-infesting agricultural land.

Cooking would likely destroy the fungal material, but since the fungus doesn't pose a health risk to begin with, this is not the main concern. The primary reason for discarding infected tubers is their poor texture and appearance.