Mosaic- PLANT DISEASE

Mosaic, plant disease 

Mosaic, plant disease caused by various strains of several hundred viruses. A number of economically important  variety of crops, horticultural and vegetable crops are susceptible to mosaic infections, such as  roses, beans, tobacco, tomatoes, potatoes,cassava, beet, alfalfa, cucumbers and peppers including tobacco,
Tulip mosaic virus “breaks” tulip and lily flowers, causing attractive and colourful streaking; this rare, unusual effect drove some of the frenzy of Tulip Mania in the 17th century. Mosaic is a viral diseases found throughout the United States.

Mosaic symptoms are variable but commonly include irregular leaf mottling (light and dark green or yellow patches or streaks). Leaves are commonly stunted, curled, or puckered; veins may be lighter than normal or banded with dark green or yellow. Plants are often dwarfed, with fruit and flowers fewer than usual, deformed, and stunted. Mosaic symptoms may be masked or latent, especially at temperatures above 27 °C (81 °F), and are sometimes confused with nutrient deficiency or herbicide injury. The causal viruses are spread by aphids and other insects, mites, fungi, nematodes, and contact; pollen and seeds can carry the infection as well.

Mosaic can be avoided by using virus-free seeds and plants, growing resistant varieties, separating new from old plantings, rotating annuals, and observing stringent sanitation and pest-control measures.

This virus infects more than 150 types of plants, including many fruits, vegetables, and flowers. It is characterized by leaves mottled with yellow, white, and light and dark green spots or streaks. Some of the most commonly infected plants include tomatoes, squashes, cauliflower, and cucumbers.

Cucumber mosaic virus is one of the most common types of mosaic viruses, and it is usually spread by aphids. As can be inferred from its name, cucumber mosaic virus often affects cucumbers, but it is also a common problem for tomatoes, melons, squashes, and other plants.

Tobacco mosaic virus spreads through seeds and direct contact, and the best way to avoid it is to grow resistant varieties.


IDENTIFICATION
HOW TO IDENTIFY MOSAIC VIRUSES AND DAMAGE
Viral diseases are difficult to identify because symptoms vary from plant to plant and may also vary depending on the age of the plant and its growing conditions. However, the most common ways of identifying mosaic viruses are listed below.

The leaves are mottled with yellow, white, and light and dark green spots, which appear to be elevated. This gives the leaves a blister-like appearance.
Plants are often stunted, or they grow poorly.

Plants may have other deformities and their leaves may be crinkled or wavy.
Cucumber mosaic virus: Infected plants are stunted and often exhibit “shoestring sydrome,” which is a characteristic malformation in which the edges of the leaves fail to develop, with the leaf veins developing as long, narrow strips. Tomatoes are small and misshapen.

Tobacco mosaic virus: Infected plants have mottled and yellowed leaves and twisted or deformed young growth.

Cucumber mosaic virus causes severe damage and discoloration to a spinach plant.
Plant viruses can be difficult to detect as symptoms look similar to many nutrient deficiencies and vary depending on the age of the plant when infection occurs. Look for:

Yellow, white or green stripes/ streaks/ spots on foliage
Wrinkled, curled or small leaves
Pronounced yellowing only of veins
Stunted growth and reduced yields
Infected fruit appears mottled and develops raised “warty” areas
Mosaic virus overwinters on perennial weeds and is spread by insects that feed on them. Aphids, leafhoppers, whiteflies and cucumber beetles are common garden pests that can transmit this disease. Soil, seed, starter pots and containers can be infected and pass the virus to the plant. Cuttings or divisions from infected plants will also carry the virus.


CONTROL AND PREVENTION
HOW TO CONTROL MOSAIC VIRUSES
Once plants are infected, there are no controls. Remove all the infected plants and destroy them. Also, be sure to disinfect your gardening tools.

PREVENT MOSAIC VIRUSES
Plant resistant plants when available in your garden. Resistant varieties of tomatoes have yet to be developed for cucumber mosaic virus, but tomatoes that are resistant to tobacco mosaic virus may have some slight resistance to cucumber mosaic virus as well.

Mosaic viruses are mostly spread by insects, especially aphids and leafhoppers. You can try covering your plants with a floating row cover or aluminum foil mulches to prevent these insects from infecting your plants. Look at our other tips for controlling aphids.

Control your weeds. Some types may serve as hosts for the disease.
To avoid tobacco mosaic virus, soak seeds in a 10 percent bleach solution before planting and avoid handling tobacco near plants.

PLANTS AFFECTED
Tomatoes
Cucumbers
Cauliflower
Squash and Zucchini

Treatment

There are no cures for viral diseases such as mosaic once a plant is infected. As a result, every effort should be made to prevent the disease from entering your garden.

Fungicides will NOT treat this viral disease.

Plant resistant varieties when available or purchase transplants from a reputable source.
Do NOT save seed from infected crops.

Spot treat with least-toxic, natural pest control products, such as Safer Soap, Bon-Neem and diatomaceous earth, to reduce the number of disease carrying insects.

Harvest-Guard® row cover will help keep insect pests off vulnerable crops/ transplants and should be installed until bloom.

Remove all perennial weeds, using least-toxic herbicides, within 100 yards of your garden plot.
The virus can be spread through human activity, tools and equipment. Frequently wash your hands and disinfect garden tools, stakes, ties, pots, greenhouse benches, etc. (one part bleach to 4 parts water) to reduce the risk of contamination.

Avoid working in the garden during damp conditions (viruses are easily spread when plants are wet).
Avoid using tobacco around susceptible plants. Cigarettes and other tobacco products may be infected and can spread the virus.

Remove and destroy all infected plants