There are numerous plant virus diseases, most of which are specific to one plant or group of plants. They can produce various symptoms, depending on the type of virus they are and the plant affected.
Virus infections are normally transmitted by sap-sucking insects, such as greenfly and whitefly that move from plant to plant, spreading the disease. However, they can also be spread by using tools infected with the virus and some may even be seed-borne.
Luckily, they are not a very common problem, although potatoes and cucumbers are susceptible to a mosaic virus, that affects the crop and yield..
Viruses are normally seen as spotting, marbling, yellowing or mosaic patterning on the leaf. Severe virus outbreaks can also lead to growth distortions or even death of the affected part.
Treatment and control
Protect vulnerable plants by preventing attacks from sap-sucking insects, by spraying with a suitable insecticide. Sterilise secateurs and lopper blades with household bleach.
Unfortunately, there are no chemical controls for plant virus diseases. Dig up and dispose of affected plants – to prevent it spreading to other plants.