Arabis Mosaic Virus

Genus Nepovirus in the family Secoviridae

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Hosts

• Field-grown hemp
• Many crops such as celery, grapes, hops, horseradish, lettuce, peach, raspberry, rhubarb, strawberry, sugar beet
• Geranium
• Lilac

Symptoms

ArMV causes a range of symptoms including leaf mottling (patterns and mixes of yellow and green shades), twisted and curled foliage, and stunted shoot growth. Symptoms may resemble herbicide damage. Overall plant growth can also be slightly slowed to severely stunted. In many non-hemp host plants, the virus causes no symptoms. The effects of viruses on cannabis yield and flower quality have not been determined.

Disease Cycle

The virus is spread by dagger nematodes (Xiphinema spp.) from infected plants to healthy plants. It is then spread further in propagation by taking cuttings from an infected mother plant. 

Time for Concern

Starting at the middle of the growing season through to harvest. 

When and Where to Scout

Starting in late spring, observe plants for unusual leaf coloration, especially on plants growing closest to alfalfa fields.

Threat Level

Low.

Occurrence in Utah

Arabis mosaic virus was detected on one hemp plant in a single field in northern Utah. It has not been reported widely from other U.S. states, but does occur on hemp in Europe.

Management

• Plant only certified disease-free material, and only propagate cuttings from healthy plants.
• If there is a concern about nematodes in the field, soil tests are available to determine if Xiphinema nematodes are present. There are labs around the country that can do the test.
• Remove plants with positive diagnosis.

When to Consider Treatment

At this time there is no information available that treatment is needed. 

Look-alikes

Other viruses, genetic abnormalities, nutrient deficiencies (nitrogen, iron, magnesium), herbicide damage, stunted growth due to poor growing conditions.

Photo Credits

All photos: USU Extension IPM Program

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