Leaf spot disease is the world's most significant and harmful disease of sugar beet. It can lead to yield losses of up to 40%.
Leaf spot of beet - image 1
Factors that encourage disease development are: a warm humid climate (25 degrees Celsius and 100% humidity). Beet leaves remaining on the field from previous crops, tight crop rotations, irrigation.
Pattern of damage
At first, pale gray fungal mycelia with a reddish border and a diameter of 5 mm form on the leaves (Picture 1). With heavy infections, these spots grow together so that the entire leaf is destroyed. In the completely developed spots, there are black dots which are the stromata (dense mass of fungal hyphae, reproductive organs). With high humidity, a gray felt-like coating forms on the underside of the leaves. The heart leaves remain unaffected.