What Is The Difference Between Early And Late Blight Of Potatoes?

Potatoes are a widely produced vegetable crop all over the world. The most frequent diseases affecting potatoes are early blight and late blight. Farmers generally suffer major losses as a result of their actions. You may think the main difference between the two infections is a single word. Several producers are unaware of the necessary distinction between early and late blight. So, what is the difference between early and late blight of potato?

The fundamental distinction between early and late blight of potatoes is the fungus. The fungus Alternaria solani is the main reason for early blight. The oomycete Phytophthora infestans cause late blight of the potato.

Recognizing symptoms and determining the infectious degree at an early stage is necessary. It will be efficient for disease control and prompt disease prevention. Let’s jump into the article and find out the differences. 

Are Early And Late Blight Of Potato The Same?

The most damaging foliar diseases for potato crops are late blight and early blight. In most potato-growing locations across the world, it results in significant crop losses. Late blight shows on the leaves of potatoes as pale green or olive-green spots.

Which turn brown-black, water-soaked, and greasy. Early blight shows as dark-brown to black dots that are round or uneven. Early and late blight can affect plants at any stage of growth and development.

What Is The Early Blight Of Potatoes?

Alternaria solani causes early blight or target spot. This fungus can grow in soil and plant waste. Warm, humid surroundings are ideal for their growth.

As a result, early blight in potatoes prefers warm weather. It’s an opportunistic fungus that affects the plant’s older leaves as it becomes older.

When the plant is in a state of distress. Stems are also affected by severe infestations. After a few months in storage, tubers exposed to early blight spores produce tuber blight, a rot.

What Is The Late Blight Of Potato?

Late blight is a deadly disease that affects potatoes. Phytophthora infestans are the bacterium that causes it. An oomycete is Phytophthora infestans.

This disease damages potato crops all around the world. Which results in significant economic losses. Phytophthora infestans are the most common pathogen found in potatoes.

Because Phytophthora infestans prefer wet and chilly locations to develop. Late blight grows in certain conditions very quickly.

Leaf rots or lesions can occur as a result of late blight. The infection causes plants to wilt or fold when it develops at the seedling stage.

The stems turn dark brown and rot-like in the mature stage. While the leaves develop water-soaked irregular lesions. Finally, large portions of the plant decay, resulting in the plant’s death.

What Are The Symptoms Of Early Blight And Late Blight?

Early and late blight are two diseases that attack Solanaceae plants. Both of these disorders are quite common. They are dangerous illnesses that affect potatoes. 

Early Blight Symptoms:

  • Early disease symptoms emerge at the base of the infected plant. It starts with approximately spherical brown patches on the leaves and stems.
  • The specks become yellow halos as the lesions get larger.  Dark concentric rings frequently surround lesions greater than 10 mm in diameter.
  • Eventually, many stains on a single leaf will combine. Resulting in significant damage to the leaf tissue. Early illness can result in the entire loss of lower leaves. And possibly the death of affected plants.
  • Fruit dots start at the stem. And spread outwards from the flower-fruit attachment point. The spots are typically dark to black. It is also recessed and has a characteristic concentric ring.

Lite Blight Symptoms:

  • At the tips, little water-soaked areas appear. Any region of the leaf that enlarges to develop irregular dark brown lesions with a pale green halo.
  • Extended brown lines appear on the branch from below the ground surface and surround it. When the fungal mycelium comes from diseased plants, the lesions develop on the stem. 
  • Infected tubers have reddish-brown spots that are uneven, shallow, or sunken. To varying degrees, diseased tissue is spongy and rusty colored within. 
  • Smaller young tubers are more susceptible to infection than bigger ones. And rotting is more common in thick, damp soils.

What Is The Management Of Early Blight And Late Blight Of Potatoes?

Early and late blight are two of the most common diseases that damage potatoes. To battle it, you must first understand the situation.

What characteristics lead to and support the growth of this virus. And it’s here that producers’ management systems come into play.

Early Blight Management: 

Cultural control:

  • For the next two years, avoid potatoes.
  • After watering using sprinklers, the leaves should dry fast. 
  • If it’s chilly and foggy outside, don’t water. Also, time the end of watering to avoid open lenticels. 
  • Diseases are less severe when soil fertility is high. 
  • Only harvest tubers that are completely grown. 
  • Handle potatoes with care to avoid damage. 
  • Before harvesting, rake and burn the vines. 
  • Keep tubers in a cool, dry place to speed up the suberization process.

Chemical control:

The majority of potato cultivars are sensitive to early blight. The principal control strategy is the spraying of foliar fungicides. The most common protectant fungicides for early blight treatment are mancozeb and chlorothalonil.

Yet, when disease pressure is great, they are unable to offer adequate control. Controlling high-level pressure needs the use of systemic and translaminar fungicides.

Especially when it comes to irrigation. To achieve successful control, carefully select the fungicide and rotation. It will stop the early blight pathogen from developing fungicide resistance.

Alter the method of action of fungicides. Do not use fungicides having the same mechanism of action regularly. 

Resistant cultivars:

Commercial potato varieties offer limited tolerance to early blight. In inbreeding projects, wild Lycopersicon species with high resistance levels are used.

It has resulted in the development of an early blight-resistant variety of potatoes. The visible amount of tolerance is often related to the age of the plant. Early blight resistance is high in young potato plants.

Vulnerability grows gradually following tuber and fruit commencement. The pathogen is particularly dangerous to mature plants.

Late Blight Management: 

Cultural control:

  • Burial is a good way to get rid of potato cull piles before the growing season starts. Spreading and mixing them into fields, as well as feeding them to cattle
  • Diseased plants can sprout from infected tubers. So keep volunteer potato plants under control. 
  • It is unlikely to be infected with dried and commercially stored preserved seeds.  Plant only certified potato seedlings.
  • To prevent the spread of infection throughout a field, uproot diseased plants. Or you can disced-under, destroyed with herbicide, or flame-killed.  

Resistant varieties:

Even resistant varieties will have late blight signs. It can begin whenever the circumstances are particularly favorable for the disease. Cultivars have different levels of resilience.

According to the P. infestans clonal lineage existing, this could be more or less effective. Cornell maintains a database of disease-resistant vegetable cultivars.

Chemical control:

There are chemicals designed to manage late blight on potatoes. To be most effective, apply fungicide treatments before infection. When environmental circumstances promote symptoms.

The water mold Phytophthora infestans is not a real fungus. Repeat Water mold-specific fungicide treatments as directed on the label.

The Midwest Vegetable Production Guide has an updated list of fungicides for treatment. To cut the formation of fungicide-resistant isolates, use fungicide sets rotative.

Can You Eat Potatoes With Early Blight Or Late Blight?

Our diets are incomplete without the basic potato. It’s gradually displacing grain as the world’s most important crop. And for a valid cause: potatoes grow quicker and fare better in poor conditions than other grains.

Potatoes are in everything, from fast food to pantry staples. Also in our yards, of course. Yet, we only discover issues on our farms when we cultivate the potatoes ourselves. Blight is the hardest infection to manage.

You won’t be able to do anything once it shows up on your potatoes. Things are only possible to slow it down at this point. Or, if you’re fortunate, you can resist it.

Yet, because blight is so pervasive and hard to control. You have to wonder what will happen to our favorite potatoes when they get blighted.

Blight has a nasty way of sneaking up on you. You might assume you have a plentiful supply of potatoes in your pantry. on a regular basis, only to discover some of them decomposing.  

Do you have to worry about it? In the 1970s, UK scientists undoubtedly believed so. The government of the United Kingdom took this seriously. They urged expecting women to avoid eating potatoes.

Potato tubers affected with blight have high amounts of alkaloids. Pregnant women are advised to avoid eating them. There have been no instances of anyone having major medical disorders as a result of eating blighted potatoes.

If your potato is infected with blight, you can still use it for eating. But, have the following elements:

  • It’s possible that you’ll end up with fewer, smaller tubers. Because the damaged foliage prevented them from maturing.
  • Blight spores can contaminate your potato roots if they get into the earth.  Which you will find out later. 
  • Good potato plants can be infected by diseased potatoes. If you are not careful while harvesting, the potatoes may get sore.
  • Early blight blemishes are more considerate and heal more quickly. In comparison to late blight, which can ruin your whole crops if you’re not careful.
  • If you see that your potato has been infected by blight, try to use that potato fast. As long as there are no visible flaws.  

Potatoes do not decompose as soon as infected with blight. Potato tissue breaks down in preservation because of weak secondary germs.

If you remove the brown, damaged section, blighted potatoes are fine to consume. But it is often seen that whole potatoes are unusable. which isn’t a good sight in any case.

So it’s preferable to dump it. To prevent the infection from spreading to healthy tubers, inspect your preserved potatoes on a frequent basis.

Early Blight And Late Blight Of Potato Are Respectively Caused By Which Members?

Each of them is caused by two different types of fungi. 

Early Blight Host:

Alternaria solani mainly survives the winter on contaminated crop waste. The mycelium’s black coloration makes it more resistant to lysis. This allows the plant to survive in the ground for several years.

There have been reports of thick-walled chlamydospores, although these are uncommon. The pathogen can live from year to year in moderate environments.

They survive on bushy Solanaceous plants like horsenettle and nightshade. As well as on voluntary potato plants.

Late Blight Host:

The cause of late blight is Phytophthora infestans. It’s a watery mold from the phylum Oomycetes, not a real fungus.

Oomycetes, such as P. infestans, produce big, transparent lemon-shaped sporangia on sporangiophores, or sporangia stalks. At sites where sporangia were generated, the sporangiophores display characteristic cyclic growths.

What Are The Preferred Climate For Early Blight And Late Blight Of Potatoes?

Early blight and late blight are two different types of potato diseases that affect potatoes. The preferred climate for both types of blight is cool and wet weather. 

Early Blight:

Infection thrives in warm, humid environments (between 24 and 29 degrees C/ 75 and 84 degrees F). Conidia develop in about 40 minutes in the presence of free humidity and at a temperature of 28-30°C (82-86°F).

When re-wetted, dried germ tubes can regenerate their growth. When there are alternating rainy and dry seasons, infections can arise.

Germ tubes can either directly pierce the leaf epidermis or infiltrate from stomata. Infection of potato tubers mainly arises as a result of lesions in the tuber skin caused during harvest.

Wet harvest circumstances encourage spore germination. While also creating enlarged lenticels on the potatoes which are more quickly attacked.

Late Blight:

When there is water available on the leaves of Sporangia, it can develop at temperatures ranging from 44 to 55 F.         

These easily swim through water coatings, adhere to the leaf surface, and attack the plant. By entering the leaf area with a germ tube, encysted zoospores attack it.

At temperatures between 55 and 70 degrees F, sporangia develop in a single germ tube. Nighttime temperatures of 50 to 60 degrees F, combined with rainy weather, fog, or heavy dew.

Which is excellent for late blight infection and growth. Followed by days of 60 to 75 degrees Fahrenheit and high humidity levels. If sporangia from the leaves are carried back into the ground by rainfall or water sources, tubers could get infected.

In a water film, water-borne germs generally follow branches and stolons into the soil, where they infect tubers. As a result, tubers that are close to the surface of the ground are more likely to get affected.

What Are The Disease Cycles Of Early And Late Blight Of Potatoes?

Each of them has a different appearance cycle.  

Early Blight:

Environmental factors, leaf age, and cultivar susceptibility all influence how long it takes for foliar symptoms to manifest after initial infection. Early blight is a disease that affects aged plant tissue.

Lesions occur fast on older leaves in warm, damp environments. And become noticeable within 5-7 days after infection. For sporulation to occur, a protracted wet phase is necessary.

Although it can also happen when wet and dry periods rotate. Conidiophores are formed during rainy nights and the next daytime.

They develop spores in response to dryness. Conidia dispersal causes secondary disease transmission. Mostly by wind, but also by splashing rain or above irrigation.

Early blight is polycyclic in nature, with new infections recurring in cycles. This is the time when the virus has the greatest ability to spread quickly and cause damage to the crop.

Late Blight:

Spores appear within three to five days. Infection takes 12 hours of open wetness to take hold. Within a few days of infection, lesions on the leaf appear as tiny specks.

If situations are suitable, the lesions enlarge to water-soaked gray-green spots on the plant and sporulate. Wind and rain carry the spores to healthy plants, where the disease cycle begins anew.

Late blight spreads quickly, with a disease cycle occurring every five to seven days. Spores splashed into the ground from lesions infect plants.

In the water phase, spores develop and swim to tubers, infecting principally the eyes. Patches of brown to purple color on the potato skin indicate tuber infections. Cutting slightly beneath the epidermis reveals a dark, reddish-brown, dry, corky root.


I hope you enjoyed my article on the difference between early and late blight of potatoes. Early and late blight of potatoes often creates confusion with each other.  It is important to keep track of the type of blight for your particular planting.

I hope you will find this blog post helpful for your gardening needs. If you have any questions, please don’t hesitate to reach out. Drop them in the comment section. Thank you for reading!

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