Alfalfa Mosaic Virus
Class: Viruses
Common Name
Alfalfa mosaic virus (AMV), lucerne mosaic virus, and potato calico virus
Potential Hosts
Pepper, potato, tomato, tobacco, eggplant, alfalfa, clover, and legumes
Who am I?
Alfalfa mosaic virus, the only member of the alfamovirus genus, is a viral disease transmitted by aphids, seeds, and mechanical means such as grafting. AMV symptoms vary depending on the crop and include, but are not limited to, bleached leaves and leaves exhibiting yellow-white mosaic patterns often seen without distortion. Plants infected in an early growth stage are likely to remain small.
*Note that in some instances, symptoms can disappear without leaving a trace.
Control measures
There are no treatments for viruses; if the number of plants infected with aphids is small, the plants should be removed from the field. Since the virus might have spread before symptoms appeared, focus should be on prevention, the usage of resistant varieties, and the elimination of weeds and aphids.
Cultural
It’s easier and more cost effective to overcome infestation by eliminating aphids during the initial stage of infestation. Make it a routine to monitor fields regularly and search plants for the presence of aphids on a weekly basis.
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 aphids.
Growing inside structures: The most effective way to protect your crop from aphids is simply (but costly) growing them inside a greenhouse or a dense (50 mesh) net structure.
Conventional (chemical)
In most cases, an application (1 iteration) of an imidacloprid-based product via irrigation or spray can completely eradicate an aphids infestation and prevent a buildup of the infestation. Although, this method will not keep your crop safe completely from acquiring the virus and 2-3 additional spraying application will help to reduce chances of infection.
Other applications of insecticides (molecules\active ingredient names) given by spray are:
flonicamid, imidacloprid, pymetrozine, thiamethoxam, sulfoxaflor, acetamiprid, chlorpyrifos, cypermethrin, and bifenthrin.
The use of insecticides to control the spread of aphids has its limitations. By the time it took to detect aphids and generate a response, they may have already transmitted the virus before the insecticide could kill them.
Organic
Spray-able products containing one or more of the following molecules: azadirachtin, neem oil, pyrethrins, and potassium salt of fatty acids.
*Names marked in red are considered to be highly poisonous to beneficial insects.
*Names marked in green are considered to be organic and IPM (integrated pest management) compatible.
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 of the legal uses and permissions with respect to the laws in their country and destination markets. Always read the instructions written on labels, and in a case of contradiction, work in accordance to the product label. Keep in mind that information written on the label usually applies to local markets. Pest control products intended for organic farming are generally considered to be less effective in comparison to conventional products. When dealing with organic, biologic, and to some extent a small number of conventional chemical products, a complete eradication of a pest or disease will often require several iterations of a specific treatment or combination of treatments.