There is no cure for mosaic once a plant is infected. Disease-free seed offer an effective means of control. Infection may appear at any stage of growth. Very young seedlings are killed. Surviving plants are smaller in size, quality of heads is affected and maturity is delayed.
Infected leaves have an upright habit of growth and the veins turn yellow and begin to clear.
Areas around the veins turn white causing the veins to appear enlarged. The virus is soilborne and may persist in the soil for a long period of time. The virus can be transmitted by Olpidium brassicae , a soilborne fungus found in the rootlets of many growing plants. Avoiding excessive soil moisture and rotation are means of reducing disease losses. Margins of leaves die and turn brown.