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How To Identify Tomato Plant Mosaic Virus

There are many viruses which can attack your vegetables and the mosaic virus is becoming more common each year.  The key sign is mottled areas of yellow leaves which at the same time become distorted. See the picture below and click on it for a larger picture. It mainly affects tomato and cucumber plants.


Yellow leaves caused by mosaic virus The tomato plant picture on the left (click it to enlarge it) shows the distinctive yellow leaves which are almost bronze in colour when the disease is advanced.

There are many variations of mosaic virus, spotted wilt, streak, fern leaf to name but a few. They have slightly different symptoms but all can be identified but the distinctive yellowing leaves.


How to Treat Mosaic Virus
There is no known cure, but all is not necessarily lost. Some advice is to dig up the plant and burn it but that advice is now generally thought to be out of date. Mosaic virus is transmitted from plant to plant in two key ways, by insects and by you, the gardener. Both result in the same symptoms of yellow leaves.

The virus won't kill your plant, it will reduce its vigour and ability to produce crops. So, if you want to keep your plant then follow the steps below.

1. After handling a plant with mosaic virus always wash your hands thoroughly before touching another plant. This will stop the disease being transmitted to your other plants

2. Try and leave tending to plants with any sign of the disease to the last, especially when removing yellow leaves as described below.

3. Remove all yellowing or bronzed leaves and put them away for burning.

4. Make sure that infected plants are well watered and well fed but not overfed.

If you take the steps above, the plants will recover a lot of their vigour, the yellow leaves will slowly reduce and the danger of cross-infection will be minimal. Clear up all debris during the season and especially at the end of the season, no signs of infected leaves should be left on the soil.

Next season, definitely don't plant tomatoes or cucumbers in the same area again. If you are using a greenhouse, remove all the top soil and replace it with new soil. Increasing the temperature in the greenhouse above 24°C (75°F) has been proven to reduce the effects of mosaic virus.