Skip to Content

What is Potato Scab? I Show You How To Prevent It!

This article may contain affiliate links. We get paid a small commission from your purchases. More Affiliate Policy

Potato scab is a disease that affects potatoes, tomatoes, peppers, eggplants, and other plants. There are two types of potato scabs: wet and dry.

Potato scab is caused mainly by the Streptomyces fungus. Showing signs of small brown spots to large patches. It is caused by dry alkaline soil. To prevent it use slightly acidic soil and ensure the potatoes do not dry out completely.

Dry potato scab looks like tiny brown dots on the leaves or skin and can cause some damage to the plants. It becomes large blister-like lesions as it progresses and filled with fluid and eventually ruptures to form large areas that are dark brown in color (or black if they become advanced).

Potato scab prevention includes using straw mulch on the plants, which can help keep soil temperatures cool throughout the day and night.

Picture of potatoes with potato scab

To prevent potato scab, a gardener can plant potatoes in soil with a pH between 6 and 7. This will increase the number of nutrients for the potatoes to grow and help with their overall health.

What Is Potato Scab?

Potato scab is a plant disease that occurs because of exposure to the fungus Rhizoctonia Solani. It is fatal to potatoes, and wind or water can transfer it. It affects all types of potatoes, but some are more resistant than others. The wet leaves or soil carries the spores. Potato scab infects potatoes when it gets on their skin and leaves small brown patches that you can easily see with the naked eye.

The Potato scab fungus enters through wounds in the leaves and then invades plant tissue under humid conditions. It spreads fast because it can live as spores in the soil for up to two years. These spores are resistant to chemical treatments that would usually kill other fungi.

Potato scabs make the skin of the potato turn black and give off an unpleasant odor. It can affect all parts of the body, though it is more common on the skin. It can be transmitted by spores, mainly through water droplets or wind currents.

The most common signs of potato scabs are discoloration, deformation, and decay. It can spread and infect other plants close to potato plants, such as tomatoes or eggplants.

Why Do Grapes Turn Brown on the Vin...
Why Do Grapes Turn Brown on the Vine?

What Are the Signs of Potato Scab in Your Garden?

A tiny, round, brownish discoloration on the underside of a leaf is usually the first sign of potato scab. These spots will become more pronounced as they develop. They may eventually grow into other areas that are visible from above and tend to have rough edges.

Some other signs of potato scab in your garden include:

  • The average size of the affected area will increase over time.
  • There may be a yellowish discoloration on the upper side of the leaves.
  • Leaves may become crinkled or curled as well as twisted around their stems.
  • You may see surface cracks in the soil where you once planted the potatoes.

How Potato Scab Affects Potatoes

Potato scab starts as spots that are usually dark brown, on the leaves and stems. The fungus spreads quickly, causing patches of dry, crinkled leaves with little or no green color. Eventually, the plant will die off because it can not get enough nutrients from the soil to grow.

The presence of fungi will cause the disease because it introduces spores to the plant. These spores will then infect the potatoes and cause decay.

What Are the Causes of Potato Scab?

A fungus that grows on the surface of the potato caused the potato scab. You can prevent the disease by removing the leaves of diseased plants and using organic mulch.

The fungus spores spread via contact between healthy and diseased plants and can also be transferred by splashing rain or irrigation water onto the plant.

Potato scab affects all types of potatoes but grows best in moist, humid conditions. Small, circular brown or white spots on the surface and dark-green areas under these brown spots characterized it.

The fungi that cause this disease live only on plant debris and do not need to live on potatoes to reproduce and spread. This means you can have a potato scab without having any potatoes nearby when it starts to produce spores.

Fungi that live in the soil can cause a potato scab. Animals or plants can spread it. When gardeners plant potatoes, the spores that cause the scab fungus can come into contact with them.

The spores will then enter the potatoes through their leaves or stems if you have cut them to get rid of them. When these spores grow on the potatoes, they will form a black growth over the surface.

How Gardeners Can Prevent It

The potato scab can cause the skin to develop a rough texture that makes it difficult to peel. This fungus damages the leaves and can eventually affect the potatoes themselves, which causes them to rot.

It is essential to keep your soil moist during periods of drought to prevent this fungus, but not too wet when there is heavy rain. You can replace your plants as soon as they start showing signs of potato scab.

The best way to prevent potato scab is to plant resistant varieties, but if it has already started on your plants, you should try the following:

  • Keep your garden area as clean as possible from other diseases-this will also discourage potato scabs.
  • Use only high-quality seed potatoes-this will reduce the chance of growing diseased plants.
  • Cover long rows of potatoes with plastic sheeting or tarps after planting them out-this will keep the potatoes dry during rainy periods and prevent infection from spreading upwards into healthy leaves.
  • Sprinkling wood ashes on potatoes before planting can help reduce the number of potato bugs and their damage to your plants.

Effective Ways To Prevent Potato Scabs

Test the soil To Confirm pH Balance

It is essential to test your soil to confirm that it has the appropriate pH balance. You can purchase a pH kit at most garden stores. If you do not have a garden store in your area, you can use the color matching scale on the back of most liquid plant foods as an indicator of pH.

Maintain a Consistent Soil Moisture Content

Gardeners should keep the soil moisture content at an optimum level to keep plants healthy and thriving.

Use a Fungicide

You can use fungicides to kill fungi. You can do this on plants in a garden. Gardeners spray fungicides on plants or crops that fungi may have infected.

Plant Potatoes With Varieties That Resist Scab

It is essential to know about potato varieties that resist scab before planting them in your garden. Varieties such as Viking and Kennebec are resistant to scab, and you can grow them throughout the growing season. There are many resistant varieties to this disease.

The following are some potato varieties that resist scab:

  • Viking
  • Kennebec
  • Norland

How To Minimize Damage From Already Infected Potatoes?

It is essential to try to minimize the damage caused by infected potatoes. To do this, make sure that you don’t place them in a place where they can harm other healthy potatoes. It is also essential to keep them dry so that they do not further spread the damage.

As soon as you see any signs of decay, throw them out and make sure they don’t come into contact with other potatoes.

Potato Scab Prevention Tips for Organic Gardeners

Potato scabs can be prevented by following these steps:

  • Rotating crops will help prevent diseases spread from a previous crop to your new one, and vice versa.
  • Store your seed potatoes (or whichever variety you’re using) in cold storage for at least two weeks before planting them in your garden.
  • Planting potatoes deep so that there’s not much surface area exposed to sunlight and air would help minimize damage from pests like potato scabs.

Tips to Grow Healthy Potatoes in the Garden

Potato scab is a fungal disease that you can easily prevent once you know the necessary steps:

The first step is to provide the right conditions for healthy growth. Your potatoes should have access to plenty of sun and well-drained, loose soil. The soil should not be very rich in nitrogen, which can produce soft and abnormal tubers.

Opt for fertilizers that provide phosphorus and potassium instead; these will help maintain healthy plant growth without damaging your crop. Keep your potatoes from being exposed to dew or rain during the night when they are very vulnerable to infection after harvesting them for storage. Cover them with hay or dry leaves.

I created a video that will show you tips on growing potatoes to have a better result. You can watch it below.

What To Plant In Your Garden To Prevent Potato Scab

Just make sure you take into account the regional climate and soil conditions before making your decision. Potato scabs can develop if you expose potatoes to water for too long, so it’s important to know what type of potatoes you’re planting and how you’ll store them before you plant them.

The best way to prevent this disease is by planting resistant varieties. There are numerous varieties of potatoes that are resistant to this disease. It’s best to avoid those susceptible to potato scab if your garden is prone to heavy rainfall or wet conditions.

When Is the Best Time of Year To Plant Potatoes To Prevent Potato Scab?

The time to plant potatoes is always a good discussion topic for gardeners. You can grow potatoes in the spring or the fall. It depends on what type of soil you have and which pest you are trying to avoid.

If you plant them in the fall, they can’t form an adequate amount of skin and may not protect against other diseases like late blight or dry rot. If planted in the winter, potatoes are more likely to succumb to potato scabs.

Many factors go into figuring out when the best time to plant potatoes. One factor is the temperature. You can’t plant potatoes before the soil has warmed up to at least 55 degrees Fahrenheit.

Can Fungicides or Herbicides Prevent Potato Scab?

To try and control potato scabs, you can apply some fungicides to both seed potatoes and existing crops. Gardeners need to know what type of fungicide they should use, as some will only kill specific types of fungi.

Fungicides or herbicides are chemicals that kill fungi and weeds. Potato Scab is a disease that affects potatoes, caused by a fungus called Rhizoctonia Solani.

You can spray fungicides or herbicides on the fields with the hope of getting rid of any fungi or weeds before they have a chance to spread to the potatoes. These sprays can keep the fungus from spreading and infecting other plants.

Conclusion on what is potato scab

Potato scab is a common problem that occurs when the weather becomes humid, warm, and wet. It will cause potatoes to split open and grow brown spots. Therefore, the best time of year to plant potatoes is in the early spring.

If you found value in this article, subscribe to the blog for all future updates. You can do that below.