Cassava mosaic virus
Class: Viruses
Common Name
Cassava mosaic virus (CMV) and cassava mosaic disease (CMD)
Potential Hosts
Cassava (synonyms: yucca, manioc, and mandioca)
Who am I?
Cassava mosaic virus is one of the most economically important threats to cassava-growing regions. Over the years, several different species of viruses have been identified and shown to possess the ability infecting cassava in various countries, such as India, Africa, and South America.
Cassava mosaic virus is a member of the geminiviruses family and is transmitted in a persistent manner; whitefly adults feed on infected plants for more than a couple of minutes, sometimes hours. After the uptake, the virus has to circulate in the adult whitefly before it can infect healthy plants. In other words, the virus is acquired and transmitted by its vector in long periods of time that are measured in hours. Other than adult whiteflies, the spread occurs due to contaminated planting materials and occasionally by mechanical means.
Whiteflies are attracted to new foliage and colonize them quickly. A single whitefly contracted with the virus only needs about 10 minutes of feeding time to infect young leaves. When multiple infected whiteflies feed on a plant, the chances of the plant acquiring the disease are significantly higher.
Symptoms
The key infection period for the virus begins 2-3 weeks after planting crops and the formation of new leaves have emerged. The symptoms appear 3-5 weeks after the plant is infected.
The symptoms appear as a mosaic pattern and discolored of leaves. Plant stunting, mottling, misshaped and twisted leaflets, and a reduction in the size of plants and roots also occurs.
Control measures
Cultural
Use resistant crop varieties whenever possible; work with a disease tolerant variety.
Do not use planting materials that came from an unknown distributor and are of bad quality.
Sanitation: Keep the crops’ close surroundings and environmental conditions neat by removing weeds and closeby plants that are non-cultivated and unprotected, which can attract whiteflies.
Conventional (chemical)
Maintaining a whitefly-free environment is not feasible due to their high resistance against insecticides. Additionally, if the cause of the virus is due to moving infected planting material then eradicating the whitefly population will not resolve the situation.
Important Note: The virus’s high rate of recombination and co-infection capabilities makes the management practices difficult.
Caution and careful notice should be taken when using any plant protection products (insecticides, fungicides and herbicides). It is the grower’s sole responsibility to keep track after the legal uses and permissions with respect to the laws in their country and destination markets. Always read the Instructions written on the label and in any case of contradiction work with accordance to the product label. Keep in mind that information written on the label usually apply only to local markets. Pests control products intended for organic farming are generally considered to be less effective in comparison to conventional product. One must keep in mind that when dealing with organic, biologic, and to some extent a small number of conventional chemical products that a complete eradication of a pest or a disease will often require several iterations of a specific treatment or combination of treatments.