Mosaic virus infects plant cells and interferes with normal growth and chlorophyll production, producing the characteristic mosaic pattern on leaves. Symptoms vary with the tomato variety, plant age and growing conditions and can include mottling, distorted or fern-like leaves, stunting and unevenly ripened fruit.

The virus is extremely persistent and spreads mainly through infected plant material, contaminated hands, tools, stakes and other surfaces. Unlike many plant viruses, it does not need an insect vector to move efficiently from plant to plant.

How to Fix It

There is no cure for an infected plant. Remove badly affected plants and dispose of them rather than composting them. Wash your hands and thoroughly clean tools, stakes, pots and other equipment that may have contacted infected plants before handling healthy plants.

Start with certified disease-free seed or transplants and choose resistant varieties where available. Avoid handling plants after touching tobacco products, and don't save seed from infected plants.

There is no practical biological control that cures mosaic virus. Prevention, resistant varieties and strict sanitation are the most effective controls.