Alfalfa Mosaic Virus Detected In Soybeans

 

Alfalfa mosaic virus-like symptoms (Figure 1) were found at a very low incidence in a few soybean fields scouted last week. Leaves from the potentially infected plants were subjected to laboratory test and were confirmed to be positive for Alfalfa mosaic virus (AMV). Some of the soybean fields that were found with AMV were adjacent to an alfalfa field.

 

 

 

Alfalfa mosaic virus causes bright yellow mosaic patterns on the leaves. Infected leaves may also be distorted or have a rough leaf surface (rugosity). Symptom severity may vary from soybean cultivar to cultivar and will also depend on the time of infection. Sometimes infected plants may recover from infection and become symptomless later in the season. Alfalfa mosaic virus is transmitted by over 15 species of aphids including the soybean aphid. It can also be seedborne but the rate of AMV seed transmission is very low. Aphids can acquire AMV from alfalfa plants or weeds such as black night shade (Figure 2 and Figure 3) and transmit it to soybeans.