Cucumber Mosaic Virus (CMV) has a very large range of host species numbering as many as 191 in as many as 40 families.
This is important to not only the vegetable grower but to ornamentals as well as it attacks anemone, begonia, butterfly bush, candytuft, china aster, chrysanthemum, columbine, dahlia, delphinium, dichondra, salvia, freesia, geranium, gilia, gladiolus, gold guinea vine, heavenly bamboo, heliotrope, houttuynia, hyacinth, iris, larkspur, lily, marigold, mandevilla, morning glory, nasturtium, passion vine, periwinkle, petunia, phlox, potato vine, viola, saffron flower, snail vine, snapdragon, sunflower, tulip, and viburnum, zinnia, ixora, passion fruit and many more.
For the vegetable grower it is a large concern as the first vegetable hosts that the pathogen prefers are cucurbits, tomatoes, peppers and bananas. It also attacks these other vegetable crops alfalfa (symptomless), artichoke,amaranth, buckwheat, cucumber, carrot, chickpea, dill, fennel, muskmelon, squash, tomato, spinach, celery, peppers, eggplant, water cress, beet, sweet potato, snap beans, turnip, chayote, gherkin, watermelon, pumpkin, citron, gourd, lima bean, broad bean, lettuce, onion, pea, rye, new zealand spinach, cabbage, rhubarb, safflower, pineapple, parsley, husk tomato, ground-cherry, eggplant, potato, rhubarb, parsnip, parsley, spinach, yams and loofah.
Perennial weeds are reservoir hosts for the phytovirus as well such as bur-cucumber, burdock, catnip, white cockle, wild ground cherry, flowering spurge, horse nettle, jimsonweed, milkweed, mock-cucumber, motherwort, ragweed, pigweed, pokeweed, nightshade, and various mints. Other weeds that are hosts include milkweed (Asclepias syriaca), yellow rocket (Barbarea vulgaris), marsh yellowcress (Rorippa islandica), and yellow toadflax (also called butter-and-eggs, Linaria vulgaris), and chickweed (Stellaria media).
Cucumber mosaic virus is one of the most widespread and devastating phytoviruses. CMV is a worldwide problem.
CMV is overwintered in many perennial weeds that serve as reservoir hosts for the phytovirus. CMV overwinters in the roots of the weeds and then in the spring when the plants grow again it becomes active. Over 60 species of aphids feed on the weeds and transmit the virus to neighboring plants. From there CMV can be spread by aphids or mechanically by tools or humans hands. It can be spread by one plant touching another as well. In years of drought the aphids can be more concentrated and the crop loss can be 100%. CMV may also be seed borne.
A systematic infection is produced by CMV. The older the plant tissues are the least they are affected by the virus. The newer cells cells and tissues that develop after infection may develop with varying degrees of severity. External symptoms of CMV may take 4 to 5 days to show after infection for young plants. More mature plants may take 14 to 15 days to show symptoms of infection.
If a plant is infected with CMV early in the growing season, few fruits will set on it and they will be of poor quality. Often with a mosaic color, stunted or misshapen. If the plant is infected later in the season, the fruit after the plant has become infected will be misshapen while fruit set on the older part of the plant may appear normal.
You are probably wondering what CMV looks like. EEK, do I have it and how do I get rid of it! Well lets take this one step at a time.
First, CMV causes the plants to become stunted. The leaves may become yellow and they may appear mottled as well as distorted and malformed. Leaflets especially on tomatoes may become narrowed or shoestring in appearance.
Next, there is no way to get rid of CMV. These steps can help you keep control of your field. Of course overall soil health is the first step.
Please do not spread CMV and remove all plants infected with CMV immediately. Not doing so will result in a rapid spread of CMV.
Do not prune or remove any part of the plant infected with CMV it is systematic, you will spread the virus.
- Plant a Beneficial Row or border for good insects.
- You must remove the weeds surrounding the field so that there is no transmission of CMV from weeds to crops. Clear at least 30 feet away from your plants.
- Use floating row covers early in the season until bloom time. This will protect you from aphids and the spread of disease.
- Remove any plants showing signs of CMV or it will spread like wildfire. Spray any plants with insecticide before removing from field, so that aphids do not jump to another plant.
- Put all plant debris in trash not compost.
- Wash hands with hot soap and water after touching infected plants, not to spread CMV.
- Sterilize tools after use, not to spread CMV.
- Till under all residue in fall.
- Control aphids and cucumber beetles.
- Rotate crops.
- Plant resistant varieties of cucurbits
- Use aluminum reflective mulch to ward off aphids
- Use a weekly mineral oil spray (if temperatures are under 90 degrees) this keeps aphids away.
- Plant early
- Plant a tall crop as a wind break
- Do not plant cucurbits next to crops infected with CMV.