Downy mildew (DM) in fodder beet is caused by Peronospora variabilis.

 

Identification

DM mainly affects younger leaves as rosettes. Systemically infected leaves are stunted, distorted, thickened and light green with curling margins. Such plants usually die. In cool, humid weather masses of fruiting structures and spores turn leaves purplish grey.

 

Red beet rosette infected with downy mildew.

 

Importance

Occasionally seen in fodder beet crops; reduces plant density.

 

Spread

Initial infection stems from infected and contaminated seed; over-wintering spores in the soil or from nearby infected crops or volunteer plants. Spores can also spread via wind over long distances.

 

Management

Rotate crops to eliminate volunteer hosts and soil-borne inoculum. Use seed from a reputable source. Seed treatments can be used.