Cercospora Leaf Spot

Cercospora beticola

Favoured by wet and humid seasons, Cercospora leaf spot (Cercospora beticola) is the most economically damaging disease of beet crops. Epidemics can cause the complete loss of crop leaves and dramatically reduce yields.

Main Host

Fodder and sugar beet.

Symptoms

First symptoms are individual circular leaf spots (3-5 mm). Spot centres are light brown with darker-brown to reddish-purple borders. Black sporulating spots can be seen (with magnification) under high humidity conditions. With disease progression, spots will coalesce, with leaves turning yellow and then brown while remaining attached to the plant.

Life Cycle

Cercospora leaf spot survives on plant debris, some weed host species and in seed. Spores distributed by wind and rain splash.

Weather Conditions

Higher temperatures and humid conditions are ideal for disease development.

Economic Impact

Cercospora leaf spot is the most damaging beet disease economically. Disease epidemics can result in complete loss of crop leaves, reducing leaf and bulb yields.

Control

Escolta has a label claim for the control of cercospora leaf spot.

2022

In recent years, following testing, populations of cercospora have been identified that are not fully controlled by Escolta. In areas where cercospora resistance is present, and in seasons favourable for disease development, Escolta may not adequately control cercospora. It's important to note that, at this stage, the resistance is limited to cercospora only and distribution of the resistance within New Zealand is not fully understood.

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Related Pests

Beet Rust

Uromyces beticola

Favoured in cool and wet seasons, Beet rust (Uromyces beticola) is commonly seen in beet crops. Characteristic symptoms are raised red pustules on leaves. Severe infestations can lead to leaf loss and reduce yields.

Ramularia Leaf Spot - Beet

Ramularia beticola

Severe infestations of Ramularia leaf spot (Ramularia beticola) can cause significant defoliation in beet crops. It is first seen as light brown angular spots with dark-brown to reddish margins. Infected leaves turn yellow and die.

Powdery Mildew - Beet

Erysiphe betae

Powdery mildew (Erysiphe betae) is commonly seen in New Zealand beet crops as greyish-white mycelium on leaves. Favoured by hot weather, severe attacks can significantly reduce yields and feed value of fodder beet crops.