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

Potato scab is a detrimental disease, impacting not just potatoes, but also tomatoes, peppers, eggplants, and other similar plants. It exhibits in two types – dry and wet forms of potato scab.

Potato scab is caused mainly by the Streptomyces fungus. They are 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 fills with fluid, eventually rupturing to form large dark brown areas (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

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

What Is Potato Scab?

Potato scab is a plant disease due to exposure to the fungus Rhizoctonia Solani. It is fatal to potatoes, and wind or water can transfer it. It affects all 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 you can easily see with the naked eye.

The Potato scab fungus enters through wounds in the leaves and 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 turn the potato’s skin black and give off an unpleasant odor. It can affect all body parts, though it is more common on the skin. Spores can transmit it, mainly through water droplets or wind currents.

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

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 Scabs?

A fungus that grows on the surface of the potato causes 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 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, they can contact the spores that cause the scab fungus.

The spores will then enter the potatoes through their leaves or stems if you cut them to eliminate 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, making peeling difficult. 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 heavy rain occurs. You can replace your plants when they show 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.
  • After planting them out, cover long rows of potatoes with plastic sheeting or tarps. This will dry the potatoes during rainy periods and prevent infection from spreading 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 the pH Balance

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

Before planting them in your garden, you must know about potato varieties that resist scabs. Varieties such as Viking and Kennebec are resistant to scabs, and you can grow them throughout the growing season. There are wide 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, ensure you don’t place them where they can harm other healthy potatoes. It is also essential to keep them dry so they do not further spread the damage.

As soon as you see any signs of decay, throw them out and ensure 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 from spreading 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 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 showing tips on growing potatoes for better results. You can watch it below.

What To Plant In Your Garden To Prevent Potato Scab

Make sure you consider the regional climate and soil conditions before deciding. 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 tend them.

The best way to prevent this disease is by planting resistant varieties. Numerous varieties of potatoes are immune to this disease. Avoiding those susceptible to potato scabs if your garden is prone to heavy rainfall or wet conditions is best.

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 your soil type and which pest you try to avoid.

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

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 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 fungicide they should use, as some will only kill specific 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 to eliminate fungi or weeds before they can spread to the potatoes. These sprays can keep the fungus from spreading and infecting other plants.

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

Can you eat potatoes with scabs?

This disease has no remedy once it has infected the crop. The tubers may appear unappealing, but they are still edible if peeled. The storage is unaffected.

How do you control common scabs?

As an in-furrow soil treatment, pentachloronitrobenzene (Blocker) has been shown to inhibit common scabs. Chloropicrin (Strike) is a soil fumigant that controls various soil-borne illnesses and effectively reduces common scabs.

What causes common potato scabs?

The bacteria-like organism Streptomyces scabies causes the common scabs of potatoes, a soil-borne illness. Potato stems are the target of this creature. Stolons of potatoes

Can I reuse potato soil?

If your potatoes were affected by blight this year, do not reuse the soil in your garden. If you want to reuse any soil, consider crop rotation – for example, cultivating the same crops in the same soil year after year.

Can you eat potatoes with disease?

Potatoes can be infected before and then afterward collected, and the ailment shows up as brown, dry, and indented regions. The natural part might be protected to eat.

Conclusion on what potato scab is

Potato scab is a common problem 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 early spring.

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