Ramularia leaf spot of sugar beets

Ramularia affects sugar beet in damp climates. This disease is reported when the summer is cool and rainy. 

Symptoms
The fungus typically attacks older leaves. Leaf spots are usually light brown and approximately 4–7 mm in diameter. Mature leaf lesions may be reddish-brown with silvery grey or white centres. Leaves then turn yellow and die. High plant density combined with a sulphur deficiency increases disease intensity. The disease favours low temperatures and high humidity; thus, as soon as warm, dry weather occurs, plants may recover.