Alternaria solani

Alternaria solani is a fungal pathogen, producing a disease in tomato and potato plants called early blight.

It produces small, darkened lesions on the plants, that spread into growing black spots of dead tissue, often killing most of the plant in the long run. Seeds infected with the disease may even damp off during germination.

This disease can be prevented with some fungicides, including azoxystrobin, potassium bicarbonate, hydrogen dioxide as well as the biological control agent Bacillus subtilis.

Other preventative measures include ensuring the healthy circulation of air in garden rows, rotating crops so that solanaceous plants are only present every three years, and choosing resistant cultivars.