Alfalfa Mosaic Virus in Chili Peppers

Alfalfa mosaic virus, abbreviated as AMV, has an extremely wide host range and has been found to infect over 400 species of plants, including solanaceous crops such as tomato, tobacco, and potato. It is transmitted by many different aphid species and can also spread through pollen and potentially seed. These factors make AMV an extremely challenging pathogen to manage, and suppression of its vector – aphids – is the only viable means of reducing AMV impact. Symptoms of AMV injury include mottled leaves, mosaics and malformations, and tuber necrosis in potato, and AMV infection significantly reduces the yield and quality of infected plants. In our preliminary research we also noted significant stunting of pepper plants, and we expect the infection to reduce the yield and quality of chili peppers as well. As a result, AMV and its vector – aphids – pose the most urgent risk to chili pepper production in Colorado.

We are currently lacking any research-supported recommendations for integrated management of the virus and its aphid vectors. For instance, it is not known which varieties of chili peppers possess natural host plant resistance to AMV, or which stages of the peppers are most vulnerable to the AMV infection and likely to suffer the most severe yield and fruit quality losses. Further, the epidemiology of AMV and aphids in chili peppers in Colorado are not known either. Improving our knowledge of the potential for plant resistance in chili pepper lines, and the timing of the highest risk for aphid movement into peppers will allow us to explore diverse IPM tactics to suppress the virus and mitigate its impact on chili pepper production in Colorado.

In this is a collaborative project with the Nachappa Lab and with the help of Professor Emeritus Mike Bartolo we are investigating whether host plant resistance within existing pepper varieties can impede the impact of the virus on plant health and productivity. We are also exploring cultural IPM tactics such as planting date modification to alleviate the effects of infection on pepper yield and quality. This project is supported by the Colorado Department of Agriculture Specialty Crop Block Grant.

symptomatic pepper plant with AMV

Pepper plant showing leaf deformation and discoloration, both of which are symptoms of AMV infection. Image credit: Taylor Janacek, Colorado State University

leaf with vein deformation

Vein deformation in leaves is another symptom of AMV infection in chili peppers. Image credit: Taylor Janacek, Colorado State University