Mosaic virus

Updated June 2026

Worst when aphids are active through spring and summer, September to March.

Mosaic viruses mottle leaves in patches of light and dark green or yellow and distort growth on tomatoes, cucurbits, beans and many others. They are spread mainly by aphids and on hands and tools, cannot be cured, and lurk on weeds, so the focus is removal and aphid control.

How to identify

• Mottled patches of light and dark green or yellow across the leaves
• Puckered, distorted, narrow or fern-like new growth
• Stunted plants and poor, often distorted fruit
• Symptoms spreading from plant to plant where aphids are active

How to prevent

• Control aphids, the main carriers of mosaic viruses
• Pull out and bin infected plants quickly to remove the source
• Wash hands and tools after handling suspect plants
• Clear weeds that host the virus and grow resistant varieties where available

How to control organically

• Remove and bin infected plants whole, never composting them
• There is no cure, so focus on stopping spread to healthy plants
• Keep aphids in check with oil and soap sprays and natural predators
• Disinfect hands and tools between plants when working near infection
• Avoid saving seed from infected plants