Cercospora Leaf Spot
Fodder and sugar beet.
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.
Cercospora leaf spot survives on plant debris, some weed host species and in seed. Spores distributed by wind and rain splash.
Higher temperatures and humid conditions are ideal for disease development.
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.
Escolta has a label claim for the control of cercospora leaf spot.
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.