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What Causes White Spots on Potatoes?

What Causes White Spots on Potatoes?

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Potatoes are consumed in many tasty culinary delights that we all enjoy. This useful vegetable is an essential ingredient in numerous dishes and bakery goods.

It is the first choice of children and is equally popular among adults.

As nutritious and delicious as this vegetable is, it may begin to cause problems when grown in an unfavorable environment and form numerous white spots.


What Causes White Spots on Potatoes?

Potatoes begin to develop white spots when their lenticels are swamped with water. If your potatoes have developed white areas and you plan to discard them, I suggest you don’t do it just yet. White spots on potatoes are a mild and reversible problem. All you need to do is improve and remedy your plant’s care routine, and you can reestablish an ongoing supply of freshly irrigated potatoes. 


What are Lenticels?

Most living beings require an adequate supply of oxygen to survive. Lenticels in potatoes are involved in gaseous exchange; they maintain a steady oxygen inflow and carbon dioxide outflow.

Lenticels are similar to stomas, often appearing on woody tissues like shoots and roots instead of more tender leafy tissues.

The lenticels found in tubers serve as nutrient stores that allow the potato plant to survive in extremes temperatures and regrow and reproduce afterward in a favorable environment.

The lenticels appear as blemishes in tubers and may swell when the potatoes are placed in water for long periods. The enlarged lenticels may significantly reduce the effectiveness of tubers and form an easy path for pathogen entry.

The surplus moisture settles in the lenticels and distends them considerably. They form when the potatoes are growing.

It frequently pops up when the potatoes are kept in storage and gives the gardener an unpleasant surprise.

The enlarged lenticels may seem like a plight to the grower. However, if not infected by any other bacterial or fungal disease, the potatoes can be recovered and are edible.


How to Prevent Lenticels from Swelling Up?

The potato plant thrives in temperate climates and high-moisture soils, ranging from 60% to 80%. Few would expect such a plant to develop abnormalities due to the accumulation of water.

However, it is a consistent occurrence. The distended lenticels appear on the potatoes in overly wet soils or excessively humid storage houses, especially when there is inadequate oxygen.

When growing a potato plant, keep in mind that it needs frequent watering, and soils need to drain exceptionally well. A soil that drains all excess water is essential for growing a healthy potato plant.

When preparing the growing bed for the plant, pay close attention to the soil’s draining ability. To do this, dig up a 12 inches (30.5 centimeters) deep and 12 inches square hole.

Fill this hole with water and let it drain before refilling it. Leave the hole open to drain for precisely an hour and note the water level. If the soil has drained less than two inches (5 centimeters), it is unsuitable for the potato plant.

However, if it has drained more than two inches, your soil is most likely appropriate. If the soil drains poorly, you can choose another soil type.

However, if that is not an option, look for an alternative soil and perform the water draining test again until you find the ideal soil.


Alternate Methods to Prevent White Spots on Potatoes


Thorough Mixing

An easy trick is to mix your soil well before planting. Mixing the soil ensures even moisture distribution and prevents the accumulation of water at any one point.


Add Compost

Similarly, you can add a layer of compost to the planting bed that is approximately 25% of its depth.

For instance, a 24 inch (61 centimeters) deep planting bed should ideally have a six-inch (15 centimeters) thick layer of well-rotted compost.

After putting in the compost, recheck the drainage by measuring the amount of time it takes for the water level to drop by 2 inches.

If the drainage time is still too long, I recommend constructing an above-the-ground bed, potato hills, or harvesting your potatoes in large, reasonably well-draining containers.


Watering Schedule

Water your potato plant only when required. This will not allow any water to accumulate in the first place.

The potato plant prefers 1 to 2 inches (2.5 to 5 centimeters) of water each week. Anything more or less than this can have adverse effects on the plant’s growth.


Submerged Roots

If your potato plant’s roots are submerged in water, it will form white spots, and the roots will eventually rot.

To kill two birds with one stone, take the roots above the underground water table after they have absorbed sufficient water.


Treating Potatoes with Enlarged Lenticels

If your potatoes have already developed white spots and seem to be in a bad state, please do not get rid of them.

The white spots have formed due to water-filled lenticels. Air-drying the affected potatoes until the bumps shrivel can get rid of the issue.

Once in normal condition, rinse them with clean water before consuming them.


Other Factors Causing White Spots

The various agents may contribute to the formation of white spots. Here are some that you should know:

  • Water that is too cold or too hot
  • Water containing abundant chlorine
  • Overwatering
  • Planting the potatoes in depressions that hold water
  • Planting the potatoes in poorly-draining pots

Follow the potato plant care guide to nurture a healthy and happy plant and prevent water from accumulating in its lenticels.


Frequently Asked Questions about White Spots on Potatoes


Can I eat the potatoes with white spots?

The white-spotted potatoes are consumable after a thorough cleaning. However, it is good to check for other abnormalities as enlarged lenticels provide easy access to fungal infections.

Eat only if the potato appears normal overall.


How do you know when a potato has an infection?

Typically, potatoes have tight skin and are free of any dark spots, bruises, and blemishes. A potato that is soft and mushy or has black specks all over it should be thrown away.

Likewise, potatoes with a musty or moldy odor are spoiled.


When should you throw out potatoes?

Potatoes with dark spots, a mushy or soft texture, and green color should be discarded. Ideally, store them in a cool place, such as in the basement or airy surroundings.

What To Read Next

Read the Article: Best Potting Mix for Vegetables

Recommended Ebook from Hydroponics Simplified: Get Started in Hydroponics

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