Johnsongrass mosaic virus

Johnsongrass mosaic virus (JGMV) is a plant pathogenic virus belonging to the genus Potyvirus, within the family Potyviridae. It is known to infect Sorghum halepense (Johnsongrass), a common weed, as well as other Sorghum species and various members of the Poaceae family. This virus is of particular concern in agricultural settings due to its potential to significantly impact cereal crops, including maize, sugarcane, and sorghum, leading to reduced yields and economic losses.

Transmission and Spread

Johnsongrass mosaic virus is primarily transmitted by aphids in a non-persistent manner. This means that aphids can acquire the virus after feeding on an infected plant for a short period and can then transmit it to other plants but lose the ability to transmit the virus after feeding on a non-infected plant. The most common vector is the Aphis maidis (corn leaf aphid). The virus can also spread through mechanical means, such as the handling of plants and the use of contaminated tools or machinery.

Symptoms

Infected plants typically exhibit a range of symptoms including mosaic patterns on the leaves, stunting, and malformation. The mosaic pattern is characterized by irregular patches of normal green color interspersed with lighter green or yellowish areas. In severe cases, the infection can lead to significant stunting of the plant and reduced vigor, ultimately affecting the yield.

Management

Management of Johnsongrass mosaic virus involves an integrated approach combining cultural, biological, and chemical strategies. Cultural practices include the removal and destruction of infected plants and weeds, especially Johnsongrass, which serves as a reservoir for the virus. Crop rotation and the use of virus-free planting material can also help reduce the incidence of the virus. Biological control methods focus on managing aphid populations through the use of natural predators or parasitoids. Chemical control options include the application of insecticides to control aphid vectors, although this is generally considered a supplementary measure due to the non-persistent nature of the virus transmission.

Economic Impact

The economic impact of Johnsongrass mosaic virus can be significant, particularly in regions where cereal crops are a major component of the agricultural sector. Infected crops may suffer from reduced yields, and in severe cases, entire fields may be lost. The cost of managing the virus, through the implementation of control measures and the potential need for increased use of insecticides, can also contribute to the economic burden on farmers.

Research

Ongoing research into Johnsongrass mosaic virus is focused on understanding the virus's biology, transmission mechanisms, and interactions with both host plants and vector species. Efforts are also being made to develop resistant crop varieties through traditional breeding methods and genetic engineering. Advances in molecular biology and virology are aiding in the identification of resistance genes and the development of diagnostic tools for early detection of the virus.