Viral disease high threat

Mosaic Viruses (CMV, ToMV, ZYMV)

Cucumber mosaic virus; Tomato mosaic virus; Zucchini yellow mosaic virus

A family of viruses causing mottled, distorted leaves and deformed fruit across tomatoes, cucurbits, beans and peppers.

Active right now (Apr) in southern/eastern Australia. Check susceptible crops weekly.

Temp range

15-32°C

Affected crops

Peak months

7 / 12

Background

Mosaic viruses are a diverse group. Cucumber mosaic virus (CMV) has one of the widest host ranges of any plant virus, infecting tomatoes, capsicums, cucurbits, ornamentals and weeds. Tomato mosaic virus (ToMV) is mechanically transmitted and can persist in seed and debris. Zucchini yellow mosaic virus (ZYMV) severely distorts cucurbits and is aphid-transmitted.

How to identify

Light and dark green mottling (mosaic pattern) on leaves
Leaf distortion — narrowed or strap-like leaves, puckered surfaces
Stunted plants, poor yield
Fruit with mottled skin, bumps or distortion (ZYMV on zucchini is striking)

Life cycle

CMV and ZYMV transmitted by aphids in a non-persistent manner (seconds of probing can transmit). ToMV is mechanically transmitted — hands, tools, contaminated seed. Many alternate weed hosts.

Weather triggers

Temperature: 15-32°C
Follows aphid activity for CMV/ZYMV. ToMV is weather-independent.

Peak season (southern hemisphere)

Jan

Feb

Mar

Apr

May

Jun

Jul

Aug

Sep

Oct

Nov

Dec

Red = active season · Dark red outlined = this month

Affected vegetables & crops

Tomato Capsicum Chilli Cucumber Zucchini Pumpkin Watermelon Rockmelon Bean Lettuce

Click any crop to see current prices and growing info.

Climate zones at risk

Tropical Subtropical Warm temperate Mediterranean Cool temperate

Organic & low-impact control

Remove infected plants promptly
Control aphids to slow spread
Wash hands and tools between plants when handling tomatoes (for ToMV)

Chemical control

No chemical cure

Always read product labels — registrations change.

Prevention

Choose resistant cultivars (especially zucchini and cucumber cultivars with ZYMV resistance)
Control aphids and their weed reservoirs
Use clean seed
Avoid tobacco handling near plants (TMV)

Companion planting

Flowering insectary plants reduce aphid numbers and thus spread of CMV and ZYMV.

Biosecurity

Some virus strains are reportable.

Sources

Agriculture Victoria — Mosaic viruses
NSW DPI — Virus diseases of vegetables

Accuracy confidence: high. We update this library as new extension guidance is published.

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