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Cucumber Green Mottle Mosaic Virus

and Watermelon Green Mottle Mosaic

Virus

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Cucumber green mottle mosaic virus (CGMMV) and watermelon green mottle mosaic

virus (WGMMV) can cause severe disease and significant economic losses in cucurbit
species such as pumpkins, watermelons, and zucchinis.

These viruses can be transmitted through seed. They spread easily when healthy

plants come into contact with contaminated equipment, hands, clothing, or plant

material. CGMMV was first discovered in the United Kingdom in the 1930s. It was

reported in North America in 2013. WGMMV was first described in 2019 from a 2007

detection in Taiwan and reported in North America the same year. These viruses are

under official control in the United States.

What To Look For

CGMMV and WGMMV can be challenging to spot. Symptoms may not appear until 6

weeks after seed sowing and may fade as plants mature. Some infected plants may

appear normal.

Look for:

Mottled leaves covered with uneven blotches or patches of different shades or

colors, including white, yellow, brown, purple, red, and pink.

Leaves with a mosaic pattern that contains even-shaped spots or streaks of

yellow, white, and green.

Fruit that appears mottled, discolored, malformed, and has spongy flesh. 

How to Prevent This Disease

Because CGMMV and WGMMV are seedborne pathogens, management should begin

with the seed. Early detection and identification are critical to prevent introduction

of these viruses.

Use seed and transplants from reputable sources. Make sure that seed is tested

and declared free of CGMMV and WGMMV. Inspect all transplants for symptoms

before planting.

For transplant production, monitor seedlings regularly and test any suspected

to be infected with CGMMV/WGMMV. If either one or both viruses are detected,

destroy all plants within 3 to 5 feet of the symptomatic seedlings to prevent the
virus from spreading further.

During grafting operations, follow strict sanitation practices for all work

surfaces and tools and put in place hygiene worker training programs that

include sanitation of boots, clothing, hands, and tools. The most effective

disinfectants are sodium hypochlorite (0.53% solution) and glutaraldehyde

(0.22%). Commercially available products such as Clorox® (Clorox Company,

Oakland, CA) or Virocid® (CID Lines N.V., Belgium) can be used as stock to

prepare a working solution.

Keep records of seed and transplant sources so they can be traced if needed.

Disinfect all agricultural machinery and equipment before moving between

fields and farms.

To prevent contamination from visitors and their vehicles, limit access to a

secure place near the entrance to the farm; this site should have cleaning and

disinfection facilities.

Eliminate potential CGMMV/WGMMV reservoirs, such as volunteer plants and

alternate host weeds, particularly any weeds in the cucurbit family.

Minimize crop handling and other procedures that may wound the plants,

especially early in the growing season, as the most severe yield losses result

from early infections.

Scout plants in the field for symptoms of CGMMV/WGMMV infection; take tissue

samples and have diagnostic testing done on suspect plants. Train field workers

and fruit pickers to report any unusual looking plants or fruit.

Follow a crop rotation strategy with 2 to 3 years between cucurbitaceous crops.

How It Is Treated

Host Removal

All infected plant material must be removed using APHIS-approved disposal

methods. Cut, rake, and burn all plant material in infected fields. If burning is not an

option, disking fields is an acceptable alternative.

To prevent infection of new host material, infested field(s) should remain free of

CGMMV/WGMMV hosts for at least 2 years. During this time, aggressive weed control

is necessary to prevent volunteer cucurbit and broadleaf weed growth. Equipment or

personnel entering fields must follow strict sanitation protocols to reduce the
likelihood of spreading CGMMV/WGMMV. Fields should be tested for the presence of

CGMMV/WGMMV before they are returned to cucurbit production. This can be done

by using sentinel plants (susceptible hosts) throughout the fields during the non-host

crop or fallow period.

Equipment Disinfection

Equipment must be power washed or steam cleaned to remove all soil and

debris before it leaves infested areas.

Saturate all surfaces with an appropriate disinfection solution.

Surfaces must be exposed to the disinfectant for at least 15 minutes before

rinsing.

Each disinfectant should be prepared daily from the stock according to

manufacturer instructions or EPA label.

Approved disinfection chemistries include:

Disinfectant (active ingredient)* Application rate

Sodium hypochlorite 0.53%

Glutaraldehyde [OHC(CH2)

3

CHO, C5H8O2] 0.22%

*Commercially available products such as Clorox® (Clorox Company, Oakland, CA)

or Virocid® CID Lines N.V., Belgium) can be used as stock to prepare a working

solution.

Seed Treatment

The only way to eliminate CGMMV and WGMMV from infected seed is to destroy the

seed.

Report Plant Pests and Diseases

Have you seen this pest or signs of pest damage? Immediately report your findings.

Find your State plant regulatory official

Find your State plant health director

Controlling CGMMV and WGMMV
Information for Cooperators

New Pest Response Guidelines

Contact Us

Lynn Evans-Goldner

National Policy Manager

Email: lynn.evans-goldner@usda.gov

Phone: 301-851-2286