Difference between Early Blight and Late Blight of Potato

Late blight and early blight are two diseases that affect potato and tomato plants of the Solanaceae family. While the early blight is caused by the fungus Alternaria in relatively warmer temperatures, late blight is caused by the oomycete Phytophthora in cooler temperatures. Find out more such differences between the early blight of potato and late blight of potato in the table below.

Early Blight of Potato

Late Blight of Potato


Early blight of potato is a disease caused by fungal species.

Late blight of potato is a disease caused by oomycetes, which is a distant relative of fungi.

Causative agent



Infectious Species

Alternaria solani and Alternaria tomatophila

Phytophthora infestans


The pathogen prefers a slightly warmer temperature in the range of 24-29 ℃

The pathogen favours a moist and cool temperature in the range of 12-18 ℃


Circular dark brown rings or lesions on older leaves, that spread to stems and leaves gradually.

Irregular-shaped lesions on the leaves, petioles and stems, the potato tubers start to rot, a whitish cottony growth of fungus is visible on the whole plant


It has a small impact on the plants.

The plants are severely affected and damaged.

Cause of infection

Prolonged period of wetness on the plants.

The spores tend to spread in cool and wet conditions.

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Frequently Asked Questions


How do you identify early blight in potatoes?

Early blight in potatoes can be identified by the presence of dark brown concentric lesions on older leaves.


Can you eat potatoes with early blight?

No, it is not recommended to eat potatoes with early blight infection.


How do you treat early potato blight?

Early potato blight can be prevented by applying fungicides to the plant and preventing the plant from constant wetting


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