24 Potato Diseases and How to Identify Them (With Pictures)

There are many potato diseases that can affect the growth and health of potato plants, including viral, bacterial, fungal, and nematode infections.

In this blog post we will show you how to identify them with pictures

Violet root rot

Helicobasidium mompa, a fungal pathogen, is responsible for causing an insidious illness in potato plants known as violet root rot. The disease primarily targets the roots and tubers, manifesting symptoms such as stunted growth, leaf yellowing, and wilting. The telltale sign of violet root rot is the development of a violet-colored discoloration in the roots and stem base.

This fungal menace can persist in the soil for several years, making it crucial to employ crop rotation and fungicidal treatments as effective management strategies. To prevent and control the spread of violet root rot, farmers should prioritize planting certified disease-free seed potatoes and avoid poorly drained soils. Additionally, implementing robust weed control measures can help curb the spread of the disease.

Verticillium wilt

Verticillium wilt is a fungal disease that affects potato plants, caused by the soil-borne pathogen Verticillium dahliae. The disease is characterized by yellowing and wilting of the leaves, which eventually leads to plant death. Infected plants also exhibit decreased tuber yield and quality. The pathogen can survive in the soil for several years, making crop rotation and resistant varieties important management strategies. Fungicides may also be used to control the disease, although they are not always effective

Tobacco Necrosis Virus

Tobacco Necrosis Virus is a viral affliction that wreaks havoc on potato plants. This disease, commonly referred to as TNV, is spread via aphids and has the potential to inflict significant harm on potato crops. Signs of TNV manifest in the form of leaf yellowing and necrosis, stunted growth, and diminished yields. Unfortunately, once a plant contracts TNV, there is no cure and the only recourse is to uproot and dispose of the contaminated plants to avoid further spread. 

Tobacco Rattle Virus

Did you know that there’s a virus out there that can affect potato crops around the world? It’s called Tobacco Rattle Virus (TRV), and it spreads through soil-borne nematodes. Unfortunately, TRV can cause some serious problems for potato growers, leading to lower yields and quality issues. You can spot TRV on potato plants by looking out for mosaic patterns, stunted growth, and necrotic streaks on the stems, leaves, and tubers. It’s not just the appearance of the plants that can be affected, either – TRV can also lead to smaller and fewer potato tubers, which can really impact the bottom line for growers. Let’s all keep an eye out for TRV and do our best to help potato farmers keep their crops healthy and thriving!

Blackleg and bacterial soft rot

Blackleg and bacterial soft rot are two common diseases affecting potato crops worldwide. These diseases are caused by bacteria belonging to the genera Dickeya and Pectobacterium, respectively. Symptoms of blackleg include darkening and softening of the stems, wilting, and eventual death of the plant. Bacterial soft rot, on the other hand, affects the tubers, causing them to become soft and develop a foul odor. These diseases are particularly problematic in wet conditions and can spread easily through contaminated soil, equipment, and seed potatoes. 

Potato Mop Top Virus

PMTV is characterized by a distinctive mop-top symptom, which appears as stunted growth and yellowing of leaves, followed by the formation of brown tuber necrosis and deep cracks on the surface of the potato. The virus is transmitted through infected seed tubers, soil-borne vectors, and contaminated farm equipment. 

Watery wound rot

One of the most prevalent potato diseases is watery wound rot, which is caused by the bacteria Pectobacterium carotovorum. This disease manifests as water-soaked lesions on the potato’s surface and progresses to produce soft and mushy tissue with a foul odor reminiscent of alcohol and fish. The disease can infiltrate potato crops through tainted seed potatoes, soil, or machinery. Effective measures to control its spread include using disease-free seed potatoes, crop rotation, and maintaining adequate sanitation practices. Additionally, fungicides can be used to control the spread of the disease.

Skin spot

The appearance of skin spots on potatoes is a common sight and may indicate a number of issues. These spots are often caused by exposure to light or physical damage during harvest and storage.

Ring rot

Ring rot is a serious bacterial disease that affects potato crops. It is caused by the bacterium Clavibacter michiganensis subsp. sepedonicus and can result in significant economic losses for potato growers. Symptoms of ring rot include wilted foliage, stunted growth, and dark streaks in the tuber flesh. Please throw this potatoes away when you see one.

Powdery scab

There’s a common fungal disease that affects potato crops all over the world called powdery scab. This pesky disease is caused by a soil-borne fungus called Spongospora subterranea that infects the roots and tubers of potato plants. The symptoms aren’t fun, with small, raised pustules forming on the surface of the potato tubers that eventually become powdery and scabby.

Black dot

The notorious black dot, which goes by the moniker “sugar spot,” is an inherent imperfection that arises when potatoes are subjected to extreme levels of heat or sunlight while they are still in the ground. Another possible cause of its formation is the infiltration of bacterial or fungal agents. Despite the fact that the presence of this blemish may not necessarily compromise the potato’s overall caliber, it does have the potential to mar its aesthetic appeal and hasten its spoilage.

Wart disease 

Potato wart disease, caused by the fungus Synchytrium endobioticum, is a significant threat to potato crops worldwide. This disease can wreak havoc on potato crops, causing extensive damage to tubers and resulting in significant yield losses. The fungus is highly contagious, spreading swiftly through soil, water, and infected seed potatoes. To counter this menace, farmers and gardeners alike must adopt a range of effective control measures such as crop rotation, soil disinfection, and sourcing certified disease-free seed potatoes.

Potato Leafroll Virus

Potato Leafroll Virus (PLRV) is a plant virus that poses a significant threat to the potato industry. This virus is primarily transmitted through aphids, which feed on infected plants and then spread the virus to healthy potatoes. PLRV causes a range of symptoms, including yellowing, stunted growth, and decreased yields. Additionally, infected potatoes may have an undesirable taste and texture, making them unsuitable for sale or consumption.

Pink rot

Pink rot is a common disease that affects potato caused by the fungus Phytophthora erythroseptica. It causes browning and softening of the potato tissue, resulting in significant yield losses and reduced quality. Pink rot typically thrives in warm and wet conditions, making it particularly prevalent during the rainy season. 

Latent and mild mosaic viruses

These viruses infect the potato plant and can remain latent, undetected for long periods of time, until they are triggered by environmental factors such as stress. Symptoms of infection may include mottled or distorted leaves, reduced growth, and reduced tuber quality.

Late blight

Late blight on potato is a devastating disease caused by the fungus-like organism called Phytophthora infestans. This disease can cause significant damage to potato crops, leading to severe economic losses for farmers. Late blight can affect both the leaves and stems of the plant, causing wilting and necrosis. The disease can quickly spread throughout a field, leading to rapid crop destruction if left untreated. So if you found one in your garden, I would just recommend isolate the whole tuber.

Gangrene

Gangrene on potato refers to a bacterial infection that affects the flesh of the potato and causes it to turn brown or black. This infection is primarily caused by Clostridium bacteria, which thrive in areas with low oxygen levels. The most common way for potatoes to become infected is through damage to their skins or tubers during harvesting or storage. Gangrene on potato does not pose a direct threat to human health so don’t worry if you found one. But I still wont eat it.

Common scab

Common scab is a bacterial disease that affects potato plants. It is caused by the Streptomyces scabies bacterium and can result in unsightly scabs on the surface of potato tubers. The bacteria can survive in soil for extended periods and can infect plants through wounds or natural openings. The disease thrives in alkaline soils that are dry and warm.

Brown rot

This disease is caused by the fungus Monilinia and can affect both seed and tuber potatoes. Symptoms of brown rot on potato include a brownish-black rot that can spread rapidly throughout the potato. Infected potatoes may also emit a foul odor and become soft and mushy. Yuck!

Dry rot

The disease can infect both seed potatoes and mature potatoes, leading to dark, sunken lesions on the tubers. The fungus responsible for dry rot thrives in moist, warm conditions and can spread rapidly throughout a potato field.

Black scurf and stem canker

Black scurf and stem canker are common diseases affecting potato crops worldwide, caused by the soilborne fungus Rhizoctonia solani. Symptoms of black scurf include dark, rough patches on the surface of potato tubers, while stem canker causes dark, sunken lesions on the plant stems. Fungicides may also be used to control the diseases, although their effectiveness may vary depending on the specific strain of R. solani present in the soil.

Alternaria

The fungus produces characteristic dark brown to black lesions on the skin of the potato, which can cause significant losses in crop yield and quality. Alternaria can infect potatoes at any stage of development, from the field to storage. The fungus thrives in warm and humid conditions, making it a particular threat in regions with high moisture levels. 

Potato Virus Y

Potato Virus Y is a serious plant pathogen that poses significant economic threats to potato production. It is a member of the Potyvirus genus and is transmitted through aphids and contaminated potato planting material. The virus can cause stunted growth, leaf curling, and mosaic patterns on potato leaves. It can also lead to reduced yields and quality of potato crops.

Silver scurf

The disease manifests as silver-gray, scaly lesions on the surface of the potato skin, reducing the quality and marketability of the crop. Silver scurf can also lead to storage rot, resulting in significant yield losses. 

Knowledge of the most common potato diseases and their symptoms is critical to effectively manage and prevent their spread. Furthermore, implementing good agricultural practices such as crop rotation, planting disease-free seed potatoes, and using appropriate fungicides can help reduce the incidence of potato diseases. By staying informed and proactive, farmers and gardeners can help protect their potato crops and ensure a steady supply of this important food source.

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