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.
Pepper plant showing leaf deformation and discoloration, both of which are symptoms of AMV infection. Image credit: Taylor Janacek, Colorado State University
Vein deformation in leaves is another symptom of AMV infection in chili peppers. Image credit: Taylor Janacek, Colorado State University
Dr. Ada Szczepaniec and PhD student Lara Amiri-Kazaz were awarded the Western Sustainable Agriculture Research and Education Graduate Student grant. The project, “Implementing host plant resistance and biological control for suppression of aphids and alfalfa mosaic virus in organic and conventional chile pepper production”, will be conducted over three growing seasons at family owned and operated farms near Pueblo. CO. This work builds upon already completed research that exemplified the effectiveness of host plant resistance and early planting in reducing virus incidence in the field (Janecek et al., in review, Plant Disease). The research objectives of this project are to 1) investigate the effect of host plant resistance and releases of predators that lower vector efficiency on decreasing virus incidence and severity of infection in organic and conventional fields; and 2) develop outreach and education programming to increase awareness of best management practices for the disease in chile peppers. The goal of these objectives is to quantify the benefit of using resistant varieties of peppers and releases of generalist predators in organic and conventional chile pepper fields and formulate management recommendations for farmers based on our findings. This work will improve environmental and economic sustainability of chile pepper production by exploiting the benefits of plant resilience and ecosystem services provided by natural enemies of insect vectors of plant diseases.
Western Sustainable Agriculture Research and Education project model. Image credit: Lara Amiri-Kazaz, Colorado State University